Studies have shown that patients with Pacemaker syndrome and/or with sick sinus syndrome are at higher risk of developing fatal complications that calls for the patients to be carefully monitored in the ICU. Complications include atrial fibrillation, thrombo-embolic events, and heart failure.

The risk for untreated LQTS patients having events (syncopes or cardiac arrest) can be predicted from their genotype (LQT1-8), gender, and corrected QT interval.

- High risk (> 50%) - QTc > 500 ms, LQT1, LQT2, and LQT3 (males)

- Intermediate risk (30-50%) - QTc > 500 ms, LQT3 (females) or QTc < 500 ms, LQT2 (females) and LQT3

- Low risk (< 30%) - QTc < 500 ms, LQT1 and LQT2 (males)

A 1992 study reported that mortality for symptomatic, untreated patients was 20% within the first year and 50% within the first 10 years after the initial syncope.

Those diagnosed with LQTS are usually advised to avoid drugs that would prolong the QT interval further or lower the threshold for TDP. In addition to this, two intervention options are known for individuals with LQTS: arrhythmia prevention and arrhythmia termination.

The cause of sudden death in Brugada syndrome is ventricular fibrillation (VF). The average age of death is 41. According to clinical reports, sudden death in people with Brugada syndrome most often happens during sleep. The episodes of syncope (fainting) and sudden death (aborted or not) are caused by fast polymorphic ventricular tachycardias or ventricular fibrillation. These arrhythmias appear with no warning. While there is no exact treatment modality that reliably and totally prevents ventricular fibrillation from occurring in this syndrome, treatment lies in termination of this lethal arrhythmia before it causes death. This is done via insertion of an implantable cardioverter-defibrillator (ICD), which continuously monitors the heart rhythm and will shock the wearer if ventricular fibrillation is sensed.

Studies have evaluated the role of quinidine, a Class Ia antiarrhythmic drug, for decreasing VF episodes occurring in this syndrome. Quinidine has been found to both decrease the number of VF episodes and correct spontaneous ECG changes, possibly via inhibiting I channels.

Some drugs have been reported to induce the type-1 ECG and/or (fatal) arrhythmias in Brugada syndrome patients. Patients with Brugada syndrome can prevent arrhythmias by avoiding these drugs or using them only in controlled conditions. Those with risk factors for coronary artery disease may require an angiogram before ICD implantation.

Medications to treat CPVT include beta blockers and verapamil.

Flecainide inhibits the release of the cardiac ryanodine receptor–mediated Ca, and is therefore believed to medicate the underlying molecular cause of CPVT in both mice and humans.

In recent reports, left cardiac sympathetic denervation and bilateral thoracoscopic sympathectomy have shown promising results in individuals whose symptoms cannot be controlled by beta blockers.

Diet alone cannot treat pacemaker syndrome, but an appropriate diet to the patient, in addition to the other treatment regimens mentioned, can improve the patient's symptoms. Several cases mentioned below:

- For patients with heart failure, low-salt diet is indicated.

- For patients with autonomic insufficiency, a high-salt diet may be appropriate.

- For patients with dehydration, oral fluid rehydration is needed.

The goal of management of ARVD is to decrease the incidence of sudden cardiac death. This raises a clinical dilemma: How to prophylactically treat the asymptomatic patient who was diagnosed during family screening.

A certain subgroup of individuals with ARVD are considered at high risk for sudden cardiac death. Associated characteristics include:

- Young age

- Competitive sports activity

- Malignant familial history

- Extensive RV disease with decreased right ventricular ejection fraction.

- Left ventricular involvement

- Syncope

- Episode of ventricular arrhythmia

Management options include pharmacological, surgical, catheter ablation, and placement of an implantable cardioverter-defibrillator.

Prior to the decision of the treatment option, programmed electrical stimulation in the electrophysiology laboratory may be performed for additional prognostic information. Goals of programmed stimulation include:

- Assessment of the disease's arrhythmogenic potential

- Evaluate the hemodynamic consequences of sustained VT

- Determine whether the VT can be interrupted via antitachycardia pacing.

Regardless of the management option chosen, the individual is typically advised to undergo lifestyle modification, including avoidance of strenuous exercise, cardiac stimulants (i.e.: caffeine, nicotine, pseudoephedrine) and alcohol. If the individual wishes to begin an exercise regimen, an exercise stress test may have added benefit.

Pharmacologic management of ARVD involves arrhythmia suppression and prevention of thrombus formation.

Sotalol, a beta blocker and a class III antiarrhythmic agent, is the most effective antiarrhythmic agent in ARVD. Other antiarrhythmic agents used include amiodarone and conventional beta blockers (i.e.: metoprolol). If antiarrhythmic agents are used, their efficacy should be guided by series ambulatory holter monitoring, to show a reduction in arrhythmic events.

While angiotensin converting enzyme inhibitors (ACE Inhibitors) are well known for slowing progression in other cardiomyopathies, they have not been proven to be helpful in ARVD.

Individuals with decreased RV ejection fraction with dyskinetic portions of the right ventricle may benefit from long term anticoagulation with warfarin to prevent thrombus formation and subsequent pulmonary embolism.

If untreated, this abnormal heart rhythm can lead to dizziness, chest pain, a sensation of fluttering or pounding in the chest (palpitations), shortness of breath, or fainting (syncope). Atrial fibrillation also increases the risk of stroke. Complications of familial atrial fibrillation can occur at any age, although some people with this heart condition never experience any health problems associated with the disorder.

Atrial fibrillation is the most common type of sustained abnormal heart rhythm (arrhythmia), affecting more than 3 million people in the United States. The risk of developing this irregular heart rhythm increases with age. The incidence of the familial form of atrial fibrillation is unknown; however, recent studies suggest that up to 30 percent of all people with atrial fibrillation may have a history of the condition in their family.

The underlying condition may be treated by medications to control hypertension or diabetes, if they are the primary underlying cause. If coronary arteries are blocked, an invasive coronary angioplasty may relieve the impending RBBB.

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.

People with atrial fibrillation and rapid ventricular response are often treated with amiodarone or procainamide to stabilize their heart rate. Procainamide and cardioversion are now accepted treatments for conversion of tachycardia found with WPW. Amiodarone was previously thought to be safe in atrial fibrillation with WPW, but after several cases of ventricular fibrillation, it is no longer recommended in this clinical scenario.

AV node blockers should be avoided in atrial fibrillation and atrial flutter with WPW or history of it; this includes adenosine, diltiazem, verapamil, other calcium channel blockers, and beta blockers. They can exacerbate the syndrome by blocking the heart's normal electrical pathway (therefore favoring 1:1 atrial to ventricle conduction through the pre-excitation pathway, potentially leading to unstable ventricular arrhythmias).

It can result in many abnormal heart rhythms (arrhythmias), including sinus arrest, sinus node exit block, sinus bradycardia, and other types of bradycardia (slow heart rate).

Sick sinus syndrome may also be associated with tachycardias (fast heart rate) such as atrial tachycardia (PAT) and atrial fibrillation. Tachycardias that occur with sick sinus syndrome are characterized by a long pause after the tachycardia. Sick sinus syndrome is also associated with azygos continuation of interrupted inferior vena cava.

Sudden cardiac arrest is the leading cause of death in the industrialised world. It exacts a significant mortality with approximately 70,000 to 90,000 sudden cardiac deaths each year in the United Kingdom, and survival rates are only 2%. The majority of these deaths are due to ventricular fibrillation secondary to myocardial infarction, or "heart attack". During ventricular fibrillation, cardiac output drops to zero, and, unless remedied promptly, death usually ensues within minutes.

The definitive treatment of WPW is the destruction of the abnormal electrical pathway by radiofrequency catheter ablation. This procedure is performed by cardiac electrophysiologists. Radiofrequency catheter ablation is not performed in all individuals with WPW because inherent risks are involved in the procedure. When performed by an experienced electrophysiologist, radiofrequency ablation has a high success rate. Findings from 1994 indicate success rates of as high as 95% in people treated with radiofrequency catheter ablation for WPW. If radiofrequency catheter ablation is successfully performed, the condition is generally considered cured. Recurrence rates are typically less than 5% after a successful ablation. The one caveat is that individuals with underlying Ebstein's anomaly may develop additional accessory pathways during progression of their disease.

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.

Artificial pacemakers have been used in the treatment of sick sinus syndrome.

Bradyarrhythmias are well controlled with pacemakers, while tachyarrhythmias respond well to medical therapy.

However, because both bradyarrhythmias and tachyarrhythmias may be present, drugs to control tachyarrhythmia may exacerbate bradyarrhythmia. Therefore, a pacemaker is implanted before drug therapy is begun for the tachyarrhythmia.

The number of people affected by Brugada ECG is higher in Asia than in the United States and Europe. Specifically, Brugada Type 1 ECG appears more frequently in Asia (0%–0.36% of the population) and Europe (0%–0.25%) than in the United States (0.03%). Type 2 and Type 3 ECG is more prevalent in Asia (0.12%–2.23%) than in Europe (0.0%–0.6%) or the United States (0.02%).

It is the most common cause of sudden death in young men without known underlying cardiac disease in Thailand and Laos.

Current treatment options for Boxer cardiomyopathy are largely restricted to the use of oral anti-arrhythmic medications. The aim of therapy is to minimize ventricular ectopy, eliminate syncopal episodes, and prevent sudden cardiac death. A number of medications have been used for this purpose, including atenolol, procainamide, sotalol, mexiletine, and amiodarone. Combinations can also be used. Sotalol is probably the most commonly used antiarrhythmic at this time. It has been demonstrated that sotalol alone, or a combination of mexiletine and atenolol, results in a reduction in the frequency and complexity of ventricular ectopy. It is likely that these medications also reduce syncopal episodes, and it is hoped this extends to a reduced risk of sudden death. Consequently, antiarrhythmic therapy is typically recommended by veterinary cardiologists for Boxer dogs with ARVC. Although relatively rare, oral antiarrhythmic medications may be proarrhythmic in some dogs; consequently, appropriate monitoring and follow-up is recommended.

The ideal therapy for Boxer cardiomyopathy would be implantation of an implantable cardioverter-defibrillator (ICD). This has been attempted in a limited number of dogs. Unfortunately, ICDs are programmed for humans and the algorithms used are not appropriate for dogs, increasing the risk of inappropriate shocks. In the future, reprogramming of ICDs may allow them to emerge as a viable option in the treatment for Boxer cardiomyopathy.

Defibrillation is the definitive treatment of ventricular fibrillation, whereby an electrical current is applied to the ventricular mass either directly or externally through pads or paddles, with the aim of depolarising enough of the myocardium for co-ordinated contractions to occur again. The use of this is often dictated around the world by Advanced Cardiac Life Support or Advanced Life Support algorithms, which is taught to medical practitioners including doctors, nurses and paramedics and also advocates the use of drugs, predominantly epinephrine, after every second unsuccessful attempt at defibrillation, as well as cardiopulmonary resuscitation (CPR) in between defibrillation attempts. Though ALS/ACLS algorithms encourage the use of drugs, they state first and foremost that defibrillation should not be delayed for any other intervention and that adequate cardiopulmonary resuscitation be delivered with minimal interruption.

The precordial thump is a manoeuver promoted as a mechanical alternative to defibrillation. Some advanced life support algorithms advocate its use once and only in the case of witnessed and monitored V-fib arrests as the likelihood of it successfully cardioverting a patient are small and this diminishes quickly in the first minute of onset.

Patients who survive a 'V-fib arrest' and who make a good recovery from this are often considered for implantation of an implantable cardioverter-defibrillator, which can quickly deliver this same life-saving defibrillation should another episode of ventricular fibrillation occur outside a hospital environment.

Despite increasing incidence of HFpEF effective inroads to therapeutics have been largely unsuccessful. Currently, recommendations for treatment are directed at symptom relief and co-morbid conditions. Frequently this involves administration of diuretics to relieve complications associated with volume overload, such as leg swelling and high blood pressure.

Commonly encountered conditions that must be treated for and have independent recommendations for standard of care include atrial fibrillation, coronary artery disease, hypertension, and hyperlipidemia. There are particular factors unique to HFpEF that must be accounted for with therapy. Unfortunately, currently available randomized clinical trials addressing the therapeutic adventure for these conditions in HFpEF present conflicting or limited evidence.

Specific aspects of therapeutics should be avoided in HFpEF to prevent the deterioration of the condition. Considerations that are generalizable to heart failure include avoidance of a fast heart rate, elevations in blood pressure, development of ischemia, and atrial fibrillation. More specific to HFpEF include avoidance of preload reduction. As patients display normal ejection fraction but reduced cardiac output they are especially sensitive to changes in preloading and may rapidly display signs of output failure. This means administration of diuretics and vasodilators must be monitored carefully.

HFrEF and HFpEF represent distinct entities in terms of development and effective therapeutic management. Specifically cardiac resynchronization, administration of beta blockers and angiotensin converting enzyme inhibitors are applied to good effect in HFrEF but are largely ineffective at reducing morbidity and mortality in HFpEF. Many of these therapies are effective in reducing the extent of cardiac dilation and increasing ejection fraction in HFrEF patients. It is unsurprising they fail to effect improvement in HFpEF patients, given their un-dilated phenotype and relative normal ejection fraction. Understanding and targeting mechanisms unique to HFpEF are thus essential to the development of therapeutics.

Randomized studies on HFpEF patients have shown that exercise improves left ventricular diastolic function, the heart's ability to relax, and is associated with improved aerobic exercise capacity. The benefit patients seem to derive from exercise does not seem to be a direct cardiac effect but rather is due to changes in peripheral vasculature and skeletal muscle, which show abnormalities in HFpEF patients.

Patients should be regularly assessed to determine progression of the condition, response to interventions, and need for alteration of therapy. Ability to perform daily tasks, hemodynamic status, kidney function, electrolyte balance, and serum natriuretic peptide levels are important parameters. Behavioral management is important in these patients and it is recommended that individuals with HFpEF avoid alcohol, smoking, and high sodium intake.

Familial atrial fibrillation is an autosomal dominant heart condition that causes disruptions in the heart's normal rhythm. This condition is characterized by uncoordinated electrical activity in the heart's upper chambers (the atria), which causes the heartbeat to become fast and irregular.

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.

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.