Arrhythmias and their treatment in patients with heart failure

Heart failure is almost without exception associated with arrhythmias, which may be either supraventricular or ventricular. Supraventricular arrhythmias include frequent supraventricular extrasystoles, and episodic or chronic atrial fibrillation. The absence of atrial contraction may further reduce cardiac output, as may impaired control of QRS frequency. Therefore, supraventricular arrhythmias may be markers of the degree of heart failure and these arrhythmias will respond to heart failure therapy including diuretics, nitrates and, possibly, angiotensin-converting enzyme (ACE) inhibitors. Ventricular rate will be controlled by cardiac glycosides and further rate reduction obtained by verapamil or diltiazem. The rationale for this therapy is to optimize heart rate without compromising contractility. Severe heart failure is generally accompanied by severe ventricular arrhythmias including repetitive forms. Improving left ventricular function by ACE inhibition is accompanied by a reduction in the number of ventricular premature complexes and also a reduction in the rate of ventricular tachycardia. ACE inhibition reduces mortality but does not seem to influence sudden death rate, and sudden death patients may have different neurohormonal responses compared with patients destined to die of progressive heart failure. Uncontrolled trials with class IA or class III antiarrhythmic drugs have suggested that prognosis may be improved, but other studies have pointed out the increased risk of proarrhythmic responses in patients with low ejection fraction.