Arrhythmias due to medications have been reported since the 1920s with the use of quinine. In the 1960s and 1970s problems with antihistamines and antipsychotics were discovered. It was not until the 1980s that the underlying issue, QTc prolongation was determined.

There are many classes of antiarrhythmic medications, with different mechanisms of action and many different individual drugs within these classes. Although the goal of drug therapy is to prevent arrhythmia, nearly every anti arrhythmic drug has the potential to act as a pro-arrhythmic, and so must be carefully selected and used under medical supervision.

Not required for physiologic sinus tachycardia. Underlying causes are treated if present.

Acute myocardial infarction. Sinus tachycardia can present in more than a third of the patients with AMI but this usually decreases over time. Patients with sustained sinus tachycardia reflects a larger infarct that are more anterior with prominent left ventricular dysfunction, associated with high mortality and morbidity. Tachycardia in the presence of AMI can reduce coronary blood flow and increase myocardial oxygen demand, aggravating the situation. Beta blockers can be used to slow the rate, but most patients are usually already treated with beta blockers as a routine regimen for AMI.

Practically, many studies showed that there is no need for any treatment.

IST and POTS. Beta blockers are useful if the cause is sympathetic overactivity. If the cause is due to decreased vagal activity, it is usually hard to treat and one may consider radiofrequency catheter ablation.

In those that are unstable with a narrow complex tachycardia, intravenous adenosine may be attempted. In all others immediate cardioversion is recommended.

Therapy may be directed either at terminating an episode of the abnormal heart rhythm or at reducing the risk of another VT episode. The treatment for stable VT is tailored to the specific person, with regard to how well the individual tolerates episodes of ventricular tachycardia, how frequently episodes occur, their comorbidities, and their wishes. Individuals suffering from pulseless VT or unstable VT are hemodynamically compromised and require immediate electric cardioversion to shock them out of the VT rhythm.

For those who are stable with a monomorphic waveform the medications procainamide or sotalol may be used and are better than lidocaine. Evidence does not show that amiodarone is better than procainamide.

As a low magnesium level in the blood is a common cause of VT, magnesium sulfate can be given for torsades de pointes or if a low blood magnesium level is found/suspected.

Long-term anti-arrhythmic therapy may be indicated to prevent recurrence of VT. Beta-blockers and a number of class III anti-arrhythmics are commonly used, such as the beta-blockers carvedilol, metoprolol, and bisoprolol, and the Potassium-Channel-Blockers amiodarone, dronedarone,bretylium, sotalol, ibutilide, and dofetilide. Angiotensin-converting-eynsyme (ACE) inhibitors and aldostrone antatagonists are also sometimes used in this setting.

Some causes of tachycardia include:

- Adrenergic storm

- Alcohol

- Amphetamine

- Anaemia

- Antiarrhythmic agents

- Anxiety

- Atrial fibrillation

- Atrial flutter

- Atrial tachycardia

- AV nodal reentrant tachycardia

- Brugada syndrome

- Caffeine

- Cocaine

- Exercise

- Fear

- Fever

- Hypoglycemia

- Hypovolemia

- Hyperthyroidism

- Hyperventilation

- Infection

- Junctional tachycardia

- Methamphetamine

- Multifocal atrial tachycardia

- Nicotine

- Pacemaker mediated

- Pain

- Pheochromocytoma

- Sinus tachycardia

- Tricyclic antidepressants

- Wolff–Parkinson–White syndrome

Anticoagulation can be used to reduce the risk of stroke from AF. Anticoagulation is recommended in most people other than those at low risk of stroke or those at high risk of bleeding. The risk of falls and consequent bleeding in frail elderly people with atrial fibrillation should not be considered a barrier to initiating or continuing therapeutic anticoagulation since the risk of fall-related brain bleeding (intracranial hemorrhage) is low and the benefit of stroke prevention outweighs the risk of bleeding. Oral anticoagulation is underused in atrial fibrillation while aspirin is overused in many who should be treated with a novel oral anticoagulant or warfarin.

The risk of stroke from non-valvular AF can be estimated using the CHADS-VASc score. A 2014 AHA/ACC/HRS guideline said that for nonvalvular AF, anticoagulation is recommended if there is a score of 2 or more, not using anticoagulation or using aspirin may be considered if there is a score of 1, and not using anticoagulation is reasonable if there is a score of 0. In contrast, guidelines from the American College of Chest Physicians, Asia-Pacific Heart Rhythm Society, Canadian Cardiovascular Society, European Society of Cardiology, Japanese Circulation Society, Korean Heart Rhythm Society, and the National Institute for Health and Care Excellence recommend the use of novel oral anticoagulants or warfarin with a CHADS2VASC score of 1 over aspirin and some directly recommend against aspirin. Experts generally advocate for most people with atrial fibrillation with CHADS2VASC scores of 1 or more receiving anticoagulation though aspirin is sometimes used for people with a CHADS2VASC score of 1 (moderate risk for stroke). There is little evidence to support the idea that the use of aspirin significantly reduces the risk of stroke in people with atrial fibrillation. Furthermore, aspirin's major bleeding risk (including intracranial hemorrhage) is similar to that of warfarin and NOACs despite its inferior efficacy.

Anticoagulation can be achieved through a number of means including warfarin, heparin, dabigatran, rivaroxaban, edoxaban, and apixaban. A number of issues should be considered, including the cost of NOACs, risk of stroke, risk of falls, compliance, and speed of desired onset of anticoagulation.

For those with non-valvular atrial fibrillation, the NOACs (rivaroxaban, dabigatran, apixaban) are neither superior to nor worse than warfarin in preventing non-hemorrhagic stroke and systemic embolic events. They have a lower risk of intracranial bleeding compared to warfarin; however, dabigatran is associated with a higher risk of gastrointestinal bleeding.

Atrial flutter is considerably more sensitive to electrical direct current cardioversion than atrial fibrillation, with a shock of only (20 to 50) J commonly being enough to cause a return to a normal heart rhythm (sinus rhythm). Exact placement of the pads does not appear important.

In general, atrial flutter should be managed the same as atrial fibrillation. Because both rhythms can lead to the formation of a blood clot in the atrium, individuals with atrial flutter usually require some form of anticoagulation or antiplatelet agent. Both rhythms can be associated with dangerously fast heart rates and thus require medication to control the heart rate (such as beta blockers or calcium channel blockers) and/or rhythm control with class III antiarrhythmics (such as ibutilide or dofetilide). However, atrial flutter is more resistant to correction with such medications than atrial fibrillation. For example, although the class III antiarrhythmic agent ibutilide is an effective treatment for atrial flutter, rates of recurrence after treatment are quite high (70-90%). Additionally, there are some specific considerations particular to treatment of atrial flutter.

The main goals of treatment are to prevent circulatory instability and stroke. Rate or rhythm control are used to achieve the former, whereas anticoagulation is used to decrease the risk of the latter. If cardiovascularly unstable due to uncontrolled tachycardia, immediate cardioversion is indicated. Regular, moderate-intensity exercise is beneficial for people with AF.

Sinus tachycardia is usually a response to normal physiological situations, such as exercise and an increased sympathetic tone with increased catecholamine release—stress, fright, flight, anger. Other causes include:

- Pain

- Fever

- Anxiety

- Dehydration

- Malignant hyperthermia

- Hypovolemia with hypotension and shock

- Anemia

- Heart failure

- Hyperthyroidism

- Mercury poisoning

- Kawasaki disease

- Pheochromocytoma

- Sepsis

- Pulmonary embolism

- Acute coronary ischemia and myocardial infarction

- Chronic obstructive pulmonary disease

- Hypoxia

- Intake of stimulants such as caffeine, theophylline, nicotine, cocaine, or amphetamines

- Hyperdynamic circulation

- Electric shock

- Drug withdrawal

- Porphyria

- Acute inflammatory demyelinating polyradiculoneuropathy

- Postural orthostatic tachycardia syndrome

Most SVTs are unpleasant rather than life-threatening, although very fast heart rates can be problematic for those with underlying ischemic heart disease or the elderly. Episodes require treatment when they occur, but interval therapy may also be used to prevent or reduce recurrence. While some treatment modalities can be applied to all SVTs, there are specific therapies available to treat some sub-types. Effective treatment consequently requires knowledge of how and where the arrhythmia is initiated and its mode of spread.

SVTs can be classified by whether the AV node is involved in maintaining the rhythm. If so, slowing conduction through the AV node will terminate it. If not, AV nodal blocking maneuvers will not work, although transient AV block is still useful as it may unmask an underlying abnormal rhythm.

Isolated PVCs with benign characteristics require no treatment.

In healthy individuals, PVCs can often be resolved by restoring the balance of magnesium, calcium and potassium within the body. In one randomized controlled trial with 60 people those with 260 mg magnesium daily supplementation (in magnesium pidolate) had an average reduction of PVC by 77%. In another trial with 232 persons with frequent ventricular arrhythmias (> 720 PVC/24 h) those with 6 mmol of magnesium (146 mg Mg)/12 mmol of potassium-DL-hydrogenaspartate daily supplementation had median reduction of PVCs by 17%.

The most effective treatment is the elimination of triggers (particularly stopping the use of substances such as caffeine and certain drugs, like tobacco).

- Medications

- Antiarrhythmics: these agents alter the electrophysiologic mechanisms responsible for PVCs. In CAST study of survivors of myocardial infarction encainide and flecainide, although could suppress PVC, they increased death risk; moricizine increased death rate when used with diuretics and decreased it when used alone.

- Beta blockers

- Calcium channel blockers

- Electrolytes replacement

- Magnesium supplements (e.g. magnesium citrate, orotate, Maalox, etc.)

- Potassium supplements (e.g. chloride potassium with citrate ion)

- Radiofrequency catheter ablation treatment. It is advised for people with ventricular dysfunction and frequent arrhythmias or very frequent PVC (>20% in 24 h) and normal ventricular function. This procedure is a way to destroy the area of the heart tissue that is causing the irregular contractions characteristic of PVCs using radio frequency energy.

- Implantable cardioverter-defibrillator

- Lifestyle modification

- Frequently stressed individuals should consider therapy, or joining a support group.

- Heart attacks can increase the likelihood of having PVCs.

In the setting of existing heart disease, however, PVCs must be watched carefully, as they may cause a form of ventricular tachycardia (rapid heartbeat).

The American College of Cardiology and the American Heart Association recommend evaluation for coronary artery disease (CAD) in patients who have frequent PVCs and cardiac risk factors, such as hypertension and smoking (SOR C). Evaluation for CAD may include stress testing, echocardiography, and ambulatory rhythm monitoring.

As an overall medical condition PVCs are normally not very harmful to patients that experience them, but frequent PVCs may put patients at increased risk of developing arrhythmias or cardiomyopathy, which can greatly impact the functioning of the heart over the span of that patient's life. On a more serious and severe scale, frequent PVCs can accompany underlying heart disease and lead to chaotic, dangerous heart rhythms and possibly sudden cardiac death.

Asymptomatic patients that do not have heart disease have long-term prognoses very similar to the general population, but asymptomatic patients that have ejection fractions greater than 40% have a 3.5% incidence of sustained ventricular tachycardia or cardiac arrest. One drawback comes from emerging data that suggests very frequent ventricular ectopy may be associated with cardiomyopathy through a mechanism thought to be similar to that of chronic right ventricular pacing associated cardiomyopathy. Patients that have underlying chronic structural heart disease and complex ectopy, mortality is significantly increased.

In meta-analysis of 11 studies, people with frequent PVC (≥1 time during a standard electrocardiographic recording or ≥30 times over a 1-hour recording) had risk of cardiac death 2 times higher than persons without frequent PVC. Although most studies made attempts to exclude high-risk subjects, such as those with histories of cardiovascular disease, they did not test participants for underlying structural heart disease.

In a study of 239 people with frequent PVCs (>1000 beats/day) and without structural heart disease (i.e. in the presence of normal heart function) there were no serious cardiac events through 5.6 years on average, but there was correlation between PVC prevalence and decrease of ejection fraction and increase of left ventricular diastolic dimension. In this study absence of heart of disease was excluded by echocardiography, cardiac magnetic resonance imaging in 63 persons and Holter monitoring.

Another study has suggested that in the absence of structural heart disease even frequent (> 60/h or 1/min) and complex PVCs are associated with a benign prognosis. It was study of 70 people followed by 6.5 years on average. Healthy status was confirmed by extensive noninvasive cardiologic examination, although cardiac catheterization of a subgroup disclosed serious coronary artery disease in 19%. Overall survival was better than expected.

On the other hand, the Framingham Heart Study reported that PVCs in apparently healthy people were associated with a twofold increase in the risk of all-cause mortality, myocardial infarction and cardiac death. In men with coronary heart disease and in women with or without coronary heart disease, complex or frequent arrhythmias were not associated with an increased risk. The at-risk people might have subclinical coronary disease. These Framingham results have been criticised for the lack of rigorous measures to exclude the potential confounder of underlying heart disease.

In the ARIC study of 14,783 people followed for 15 to 17 years those with detected PVC during 2 minute ECG, and without hypertension or diabetes on the beginning, had risk of stroke increased by 109%. Hypertension or diabetes, both risk factors for stroke, did not change significantly risk of stroke for people with PVC. It is possible that PVCs identified those at risk of stroke with blood pressure and impaired glucose tolerance on a continuum of risk below conventional diagnostic thresholds for hypertension and diabetes. Those in ARIC study with any PVC had risk of heart failure increased by 63% and were >2 times as likely to die due to coronary heart disease (CHD). Risk was also higher for people with or without baseline CHD.

In the Niigata study of 63,386 people with 10-year follow-up period those with PVC during a 10-second recording had risk of atrial fibrillation increased nearly 3 times independently from risk factors: age, male sex, body mass index, hypertension, systolic and diastolic blood pressure, and diabetes.

Reducing frequent PVC (>20%) by antiarrhythmic drugs or by catheter ablation significantly improves heart performance.

Recent studies have shown that those subjects who have an extremely high occurrence of PVCs (several thousand a day) can develop dilated cardiomyopathy. In these cases, if the PVCs are reduced or removed (for example, via ablation therapy) the cardiomyopathy usually regresses.

Also, PVCs can permanently cease without any treatment, in a material percentage of cases.

Once an acute arrhythmia has been terminated, ongoing treatment may be indicated to prevent recurrence. However, those that have an isolated episode, or infrequent and minimally symptomatic episodes, usually do not warrant any treatment other than observation.

In general, patients with more frequent or disabling symptoms warrant some form of prevention. A variety of drugs including simple AV nodal blocking agents such as beta-blockers and verapamil, as well as anti-arrhythmics may be used, usually with good effect, although the risks of these therapies need to be weighed against potential benefits.

Radiofrequency ablation has revolutionized the treatment of tachycardia caused by a re-entrant pathway. This is a low-risk procedure that uses a catheter inside the heart to deliver radio frequency energy to locate and destroy the abnormal electrical pathways. Ablation has been shown to be highly effective: around 90% in the case of AVNRT. Similar high rates of success are achieved with AVRT and typical atrial flutter.

Cryoablation is a newer treatment for SVT involving the AV node directly. SVT involving the AV node is often a contraindication for using radiofrequency ablation due to the small (1%) incidence of injuring the AV node, requiring a permanent pacemaker. Cryoablation uses a catheter supercooled by nitrous oxide gas freezing the tissue to −10 °C. This provides the same result as radiofrequency ablation but does not carry the same risk. If you freeze the tissue and then realize you are in a dangerous spot, you can halt freezing the tissue and allow the tissue to spontaneously rewarm and the tissue is the same as if you never touched it. If after freezing the tissue to −10 °C you get the desired result, then you freeze the tissue down to a temperature of −73 °C and you permanently ablate the tissue.

This therapy has further improved the treatment options for people with AVNRT (and other SVTs with pathways close to the AV node), widening the application of curative ablation to young patients with relatively mild but still troublesome symptoms who would not have accepted the risk of requiring a pacemaker.

Depending on the type of cardiogenic shock, treatment involves infusion of fluids, or in shock refractory to fluids, inotropic medications. In case of an abnormal heart rhythm several anti-arrhythmic agents may be administered, e.g. adenosine.

Positive inotropic agents (such as dobutamine or milrinone), which enhance the heart's pumping capabilities, are used to improve the contractility and correct the low blood pressure. Should that not suffice an intra-aortic balloon pump (which reduces workload for the heart, and improves perfusion of the coronary arteries) or a left ventricular assist device (which augments the pump-function of the heart) can be considered. Finally, as a last resort, if the person is stable enough and otherwise qualifies, heart transplantation, or if not eligible an artificial heart, can be placed. These invasive measures are important tools- more than 50% of patients who do not die immediately due to cardiac arrest from a lethal abnormal heart rhythm and live to reach the hospital (who have usually suffered a severe acute myocardial infarction, which in itself still has a relatively high mortality rate), die within the first 24 hours. The mortality rate for those still living at time of admission who suffer complications (among others, cardiac arrest or further abnormal heart rhythms, heart failure, cardiac tamponade, a ruptured or dissecting aneurysm, or another heart attack) from cardiogenic shock is even worse around 85%, especially without drastic measures such as ventricular assist devices or transplantation.

Cardiogenic shock may be treated with intravenous dobutamine, which acts on β receptors of the heart leading to increased contractility and heart rate.

The prognosis for TIC after treatment of the underlying tachyarrhythmia is generally good. Studies show that left ventricular function often improves within 1 month of treatment of the tachyarrhythmia, and normalization of the left ventricular ejection fraction occurs in the majority of patients by 3 to 4 months. In some patients however, recovery of this function can take greater than 1 year or be incomplete. In addition, despite improvement in the left ventricular ejection fraction, studies have demonstrated that patients with prior TIC continue to demonstrate signs of negative cardiac remodeling including increased left ventricular end-systolic dimension, end-systolic volume, and end-diastolic volume. Additionally, recurrence of the tachyarrhythmia in patients with a history of TIC has been associated with a rapid decline in left ventricular ejection fraction and more severe cardiomyopathy that their prior presentation, which may be a result of the negative cardiac remodeling. There have also been cases of sudden death in patients with a history of TIC, which may be associated with worse baseline left ventricular dysfunction. Given these risks, routine monitoring with clinic visits, ECG, and echocardiography is recommended.

Treatment of TIC involves treating both the tachyarrhythmia and the heart failure with the goal of adequate rate control or restoration of the normal heart rhythm (aka. normal sinus rhythm) to reverse the cardiomyopathy. The treatment of the tachyarrhythmia depends on the specific arrhythmia, but possible treatment modalities include rate control, rhythm control with antiarrhythmic agents and cardioversion, radiofrequency (RF) catheter ablation, or AV node ablation with permanent pacemaker implantation.

For TIC due to atrial fibrillation, rate control, rhythm control, and RF catheter ablation can be effective to control the tachyarrhythmia and improve left ventricular systolic function. For TIC due to atrial flutter, rate control is often difficult to achieve, and RF catheter ablation has a relatively high success rate with a low risk of complications. In patients with TIC due to other types of SVT, RF catheter ablation is recommended as a first-line treatment. In patients with TIC due to VT or PVCs, both antiarrhythmics and RF catheter ablation can be used. However, the options for antiarrhythmic agents are limited because certain agents can be proarrhythmic in the setting of myocardial dysfunction in TIC. Therefore, RF catheter ablation is often a safe and effective choice for treatment VT and PVCs causing TIC. In cases where other treatment strategies fail, AV node ablation with permanent pacemaker implantation can also be used to treat the tachyarrhythmia.

The treatment of heart failure commonly involves neurohormonal blockade with beta-blockers and angiotensin convertase inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) along with symptomatic management with diuretics. Beta-blockers and ACE inhibitors can inhibit and potentially reverse the negative cardiac remodeling, which refers to structural changes in the heart, that occurs in TIC. However, the need to continue these agents after treatment of the tacharrhythmia and resolution of left ventricular systolic dysfunction remains controversial.

Cardiogenic shock is a life-threatening medical condition resulting from an inadequate circulation of blood due to primary failure of the ventricles of the heart to function effectively. Signs of inadequate blood flow to the body's organs include low urine production (<30 mL/hour), cool arms and legs, and altered level of consciousness. It may lead to cardiac arrest, which is an abrupt stopping of cardiac pump function.

As this is a type of circulatory shock, there is insufficient blood flow and oxygen supply for biological tissues to meet the metabolic demands for oxygen and nutrients. Cardiogenic shock is defined by sustained low blood pressure with tissue hypoperfusion despite adequate left ventricular filling pressure.

Treatment of cardiogenic shock depends on the cause. If cardiogenic shock is due to a heart attack, attempts to open the heart's arteries may help. An intra-aortic balloon pump or left ventricular assist device may improve matters until this can be done. Medications that improve the heart's ability to contract (positive inotropes) may help; however, it is unclear which is best. Norepinephrine may be better if the blood pressure is very low whereas dopamine or dobutamine may be more useful if only slightly low. Cardiogenic shock is a condition that is difficult to fully reverse even with an early diagnosis. With that being said, early initiation of mechanical circulatory support, early percutaneous coronary intervention, inotropes, and heart transplantation may improved outcomes.

Athlete's heart is not dangerous for athletes (though if a nonathlete has symptoms of bradycardia, cardiomegaly, and cardiac hypertrophy, another illness may be present). Athlete's heart is not the cause of sudden cardiac death during or shortly after a workout, which mainly occurs due to hypertrophic cardiomyopathy, a genetic disorder.

No treatment is required for people with athletic heart syndrome; it does not pose any physical threats to the athlete, and despite some theoretical concerns that the ventricular remodeling might conceivably predispose for serious arrhythmias, no evidence has been found of any increased risk of long-term events. Athletes should see a physician and receive a clearance to be sure their symptoms are due to athlete’s heart and not another heart disease, such as cardiomyopathy. If the athlete is uncomfortable with having athlete's heart or if a differential diagnosis is difficult, deconditioning from exercise for a period of three months allows the heart to return to its regular size. However, one long-term study of elite-trained athletes found that dilation of the left ventricle was only partially reversible after a long period of deconditioning. This deconditioning is often met with resistance to the accompanying lifestyle changes. The real risk attached to athlete's heart is if athletes or nonathletes simply assume they have the condition, instead of making sure they do not have a life-threatening heart illness.

Pulsus paradoxus, also paradoxic pulse or paradoxical pulse, is an abnormally large decrease in stroke volume, systolic blood pressure and pulse wave amplitude during inspiration. The normal fall in pressure is less than 10 mmHg. When the drop is more than 10 mmHg, it is referred to as pulsus paradoxus. Pulsus paradoxus is not related to pulse rate or heart rate and it is not a paradoxical rise in systolic pressure. The normal variation of blood pressure during breathing/respiration is a decline in blood pressure during inhalation and an increase during exhalation. Pulsus paradoxus is a sign that is indicative of several conditions, including cardiac tamponade, chronic sleep apnea, croup, and obstructive lung disease (e.g. asthma, COPD).

The "paradox" in "pulsus paradoxus" is that, on physical examination, one can detect beats on cardiac auscultation during inspiration that cannot be palpated at the radial pulse. It results from an accentuated decrease of the blood pressure, which leads to the (radial) pulse not being palpable and may be accompanied by an increase in the jugular venous pressure height (Kussmaul's sign). As is usual with inspiration, the heart rate is slightly increased, due to decreased left ventricular output.

Because several well-known and high-profile cases of athletes experiencing sudden unexpected death due to cardiac arrest, such as Reggie White and Marc-Vivien Foé, a growing movement is making an effort to have both professional and school-based athletes screened for cardiac and other related conditions, usually through a careful medical and health history, a good family history, a comprehensive physical examination including auscultation of heart and lung sounds and recording of vital signs such as heart rate and blood pressure, and increasingly, for better efforts at detection, such as an electrocardiogram.

An electrocardiogram (ECG) is a relatively straightforward procedure to administer and interpret, compared to more invasive or sophisticated tests; it can reveal or hint at many circulatory disorders and arrhythmias. Part of the cost of an ECG may be covered by some insurance companies, though routine use of ECGs or other similar procedures such as echocardiography (ECHO) are still not considered routine in these contexts. Widespread routine ECGs for all potential athletes during initial screening and then during the yearly physical assessment could well be too expensive to implement on a wide scale, especially in the face of the potentially very large demand. In some places, a shortage of funds, portable ECG machines, or qualified personnel to administer and interpret them (medical technicians, paramedics, nurses trained in cardiac monitoring, advanced practice nurses or nurse practitioners, physician assistants, and physicians in internal or family medicine or in some area of cardiopulmonary medicine) exist.

If sudden cardiac death occurs, it is usually because of pathological hypertrophic enlargement of the heart that went undetected or was incorrectly attributed to the benign "athletic" cases. Among the many alternative causes are episodes of isolated arrhythmias which degenerated into lethal VF and asystole, and various unnoticed, possibly asymptomatic cardiac congenital defects of the vessels, chambers, or valves of the heart. Other causes include carditis, endocarditis, myocarditis, and pericarditis whose symptoms were slight or ignored, or were asymptomatic.

The normal treatments for episodes due to the pathological look-alikes are the same mainstays for any other episode of cardiac arrest: Cardiopulmonary resuscitation, defibrillation to restore normal sinus rhythm, and if initial defibrillation fails, administration of intravenous epinephrine or amiodarone. The goal is avoidance of infarction, heart failure, and/or lethal arrhythmias (ventricular tachycardia, ventricular fibrillation, asystole, or pulseless electrical activity), so ultimately to restore normal sinus rhythm.

Until recently, it was generally assumed that the prognosis for individuals with diastolic dysfunction and associated intermittent pulmonary edema was better than those with systolic dysfunction. In fact, in two studies appearing in the New England Journal of Medicine in 2006, evidence was presented to suggest that the prognosis in diastolic dysfunction is the same as that in systolic dysfunction.

First-line therapy for people with heart failure due to reduced systolic function should include angiotensin-converting enzyme (ACE) inhibitors (ACE-I) or angiotensin receptor blockers (ARBs) if the person develops a long term cough as a side effect of the ACE-I. Use of medicines from this class is associated with improved survival and quality of life in people with heart failure.

Beta-adrenergic blocking agents (beta blockers) also form part of the first line of treatment, adding to the improvement in symptoms and mortality provided by ACE-I/ARB. The mortality benefits of beta blockers in people with systolic dysfunction who also have atrial fibrillation (AF) is more limited than in those who do not have AF. If the ejection fraction is not diminished (HFpEF), the benefits of beta blockers are more modest; a decrease in mortality has been observed but reduction in hospital admission for uncontrolled symptoms has not been observed.

In people who are intolerant of ACE-I and ARBs or who have significant kidney dysfunction, the use of combined hydralazine and a long-acting nitrate, such as isosorbide dinitrate, is an effective alternate strategy. This regimen has been shown to reduce mortality in people with moderate heart failure. It is especially beneficial in African-Americans (AA). In AAs who are symptomatic, hydralazine and isosorbide dinitrate (H+I) can be added to ACE-I or ARBs.

In people with markedly reduced ejection fraction, the use of an aldosterone antagonist, in addition to beta blockers and ACE-I, can improve symptoms and reduce mortality.

Second-line medications for CHF do not confer a mortality benefit. Digoxin is one such medication. Its narrow therapeutic window, a high degree of toxicity, and the failure of multiple trials to show a mortality benefit have reduced its role in clinical practice. It is now used in only a small number of people with refractory symptoms, who are in atrial fibrillation and/or who have chronic low blood pressure.

Diuretics have been a mainstay of treatment for treatment of fluid accumulation, and include diuretics classes such as loop diuretics, thiazide-like diuretic, and potassium-sparing diuretic. Although widely used, evidence on their efficacy and safety is limited, with the exception of mineralocorticoid antagonists such as spironolactone. Mineralocorticoid antagonists in those under 75 years old appear to decrease the risk of death. A recent Cochrane review found that in small studies, the use of diuretics appeared to have improved mortality in individuals with heart failure. However, the extent to which these results can be extrapolated to a general population is unclear due to the small number of participants in the cited studies.

Anemia is an independent factor in mortality in people with chronic heart failure. The treatment of anemia significantly improves quality of life for those with heart failure, often with a reduction in severity of the NYHA classification, and also improves mortality rates. The latest European guidelines (2012) recommend screening for iron-deficient anemia and treating with parenteral iron if anemia is found.

The decision to anticoagulate people with HF, typically with left ventricular ejection fractions <35% is debated, but generally, people with coexisting atrial fibrillation, a prior embolic event, or conditions which increase the risk of an embolic event such as amyloidosis, left ventricular noncompaction, familial dilated cardiomyopathy, or a thromboembolic event in a first-degree relative.