Survival in congestive heart failure during treatment with drugs with positive inotropic actions

Retrospective studies have shown that patients with severe chronic heart failure who receive long-term treatment with positive inotropic agents have a high mortality rate, but in the absence of controlled trials it remains unclear whether the high incidence of fatal cardiovascular events in these patients is related to treatment or to the severity of the underlying disease. Most of the evidence that suggests a detrimental effect of positive inotropic therapy on survival remains circumstantial. The pooling of data from long-term studies of patients after an acute myocardial infarction suggests that use of digitalis may be associated with an unfavorable effect on survival. The prolonged administration of intravenous or oral catecholamines is associated with a high mortality rate, which may not be seen in similar patients treated conventionally. The presence of intrinsic sympathomimetic activity appears to neutralize the benefits of β-blockade during the first year after an acute myocardial infarction; treatment with such agents after the first year may increase mortality. Long-term treatment with phosphodiesterase inhibitors is associated with a high mortality rate, which exceeds that reported in earlier years with vasodilator therapy. Nevertheless, most of these studies of positive intropic agents were not performed to evaluate the issue of survival and did not randomly assign patients to treatment groups. Hence, we do not know that the patients entered into these studies were truely comparable to their proposed control groups. Even if pretreatment variables in the two groups were similar or if effects were made to correct mathematically for baseline differences, it is possible that unmeasured variables were present before therapy in patients treated with positive inotropic agents that contributed both to the decision to refer such patients for experimental therapy and to their extremely poor prognosis. Controlled clinical trials are needed to establish the therapeutic benefits of long-term positive inotropic therapy in patients with severe chronic heart failure and to clarify any potential effects of this therapeutic approach on survival.