[How are tachycardic cardiac arrhythmias modified by therapy of congestive heart failure?].

Previous studies have demonstrated the high prevalence of frequent and complex ventricular arrhythmias in patients with severe congestive heart failure. It has been claimed that these arrhythmias are independent risk factors of prognosis. Moreover in severely depressed left ventricular function frequent and repetitive arrhythmias may deteriorate the hemodynamic situation. Recent clinical studies have drawn increasing attention to the possibility that the desired therapeutic effect of Class I antiarrhythmic agents may be complicated by their ability to aggravate the arrhythmia or to provoke new arrhythmias. These "proarrhythmical effects" were more frequent in patients with life-threatening arrhythmias and in those with severely depressed left ventricular function. Prevention trials with Class I antiarrhythmic agents have failed to show beneficial effects on the arrhythmia profile and on the prognosis of those patients. On the other hand, it is now well recognized that the incidence of cardiac death can be reduced by the use of ACE-inhibitors in this patient population. Accordingly, there is evidence of a reduced incidence of complex ventricular arrhythmias during treatment with these drugs in some of the patients with congestive heart failure. The influence of digitalis on the arrhythmia profile and the cardiac mortality in these patients is still a matter of debate. On the other hand, there is evidence that newer positive inotropic agents such as phosphodiesterase-inhibitors rather increase the number of arrhythmias and the prevalence of sudden cardiac death in this patient population.