Genesis of arrhythmias in the failing heart and therapeutic implications.
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.
Oakley
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Department of Medicine (Clinical Cardiology), Royal Post-graduate Medical School, Hammersmith Hospital, London, United Kingdom.
D001145:Arrhythmias, Cardiac / Q000188:drug therapy / Q000209:etiology*; D003645:Death, Sudden / Q000209:etiology; D006333:Heart Failure / Q000150:complications* / Q000401:mortality; D006801:Humans; D015996:Survival Rate