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Genesis of arrhythmias in the failing heart and therapeutic implications
1Department of Medicine (Clinical Cardiology), Royal Post-graduate Medical School, Hammersmith Hospital, London, United Kingdom.
Insights
Sudden cardiac death is common in heart failure. While ventricular arrhythmias predict this risk, antiarrhythmic drugs may not prevent it; instead, improving heart function is key.
Area of Science:
- Cardiology
- Electrophysiology
- Heart Failure Research
Background:
- Sudden cardiac death (SCD) affects 50-70% of heart failure patients before advanced symptoms.
- Ventricular ectopy is a known predictor of SCD in coronary heart disease and dilated cardiomyopathy.
- The efficacy of antiarrhythmic drugs in reducing SCD risk and improving prognosis in heart failure remains uncertain.
Purpose of the Study:
- To explore the role of arrhythmias in heart failure prognosis.
- To evaluate the effectiveness of antiarrhythmic drugs in preventing sudden cardiac death.
- To identify potential mechanisms and therapeutic strategies for managing arrhythmias in heart failure.
Main Methods:
- Review of existing literature on arrhythmias in heart failure.
- Analysis of the relationship between ventricular ectopy and sudden cardiac death.
- Discussion of the impact of various drug classes on arrhythmia development and prognosis.
Main Results:
- Supraventricular arrhythmias are common and often symptomatic in heart failure, with atrial fibrillation indicating deterioration.
- Ventricular arrhythmias, except sustained ventricular tachycardia, are often asymptomatic but indicate a poor prognosis.
- Drugs like beta-blockers and ACE inhibitors may prevent arrhythmias by conserving energy or potassium.
Conclusions:
- Suppression of ventricular arrhythmias has not been proven to prevent SCD or prolong life in heart failure.
- Arrhythmias may serve as markers of poor prognosis rather than direct precursors to ventricular fibrillation.
- Improving left ventricular function through therapies may be the most effective strategy to suppress arrhythmias and prolong life.
Abstract:
Between 50 and 70% of patients with heart failure die suddenly and unexpectedly before they have deteriorated to New York Heart Association class IV symptoms. It has long been known that ventricular ectopy predicts sudden cardiac death in coronary heart disease, and this has also been shown in dilated cardiomyopathy. It is less certain whether antiarrhythmic drugs reduce this risk and improve prognosis. Supraventricular arrhythmias frequently develop in heart failure of all causes. They nearly always cause symptoms, and the establishment of atrial fibrillation may mark a permanent deterioration. Except for sustained ventricular tachycardia, ventricular arrhythmias are often occult. Hypokalemia and digitalis toxicity may have been precipitated by diuretics or interaction with antiarrhythmic drugs. In coronary heart failure, arrhythmias may be related to scar tissue or ischemia, which may also be responsible in dilated cardiomyopathy. Use of inotropes and inodilators may precipitate arrhythmias, whereas drugs that conserve energy or potassium, such as beta blockers and angiotensin-converting enzyme inhibitors, may prevent them. Since suppression of ventricular arrhythmias has not been shown to prevent sudden death or prolong life in patients with heart failure, it may be that such arrhythmias do not directly presage ventricular fibrillation except in so far as they are markers of a poor prognosis with a risk of sudden death. If so, such arrhythmias are most likely to be suppressed by agents that result in improvement of left ventricular function and, through that, prolongation of life.