Angiotensin-converting enzyme inhibitor and spironolactone combination therapy: New objectives in congestive heart failure treatment

Abstract

Secondary aldosteronism has deleterious effects in patients with congestive heart failure (CHF) and can contribute to congestion, ventricular arrhythmias, and sudden death. Mortality is higher in patients with elevated levels of plasma aldosterone. Aldosterone increases as CHF progresses as a result of activation of the reninangiotensin-aldosterone system (RAAS). This is further amplified by the routine use of diuretics. Angiotensin-converting enzyme (ACE) inhibitors produce a profound and consistent inhibition of angiotensin II production, but they exert only a mild and transient antialdosterone effect. In a number of studies involving ACE inhibitors, plasma aldosterone levels at the end of the trial do not differ significantly from baseline. Spironolactone, a specific aldosterone receptor antagonist, may exert an independent and additive effect to that of ACE inhibitors. Apart from its renal effects, recent evidence suggests that spironolactone may exert direct cardiac and vascular effects inhibiting cardiac collagen hypertrophy and limiting vascular constriction. Combining an ACE inhibitor and spironolactone may achieve a more complete inhibition of the whole RAAS and may produce further clinical benefits. The efficacy and safety of such a combination has not been properly addressed. In the CONSENSUS trial, plasma potassium and creatinine levels were not necessarily adversely affected when enalapril was added to the regimens of patients receiving spironolactone, a condition existing in >40% of the patients enrolled in this study. One prospective open study and other anecdotal reports suggest that combining spironolactone and ACE inhibitors resulted in clinical improvement without serious side effects in patients who could not tolerate further increases in the ACE inhibitor dose. Such a combination must be administered only in the absence of hyperkalemia and significant renal dysfunction and under careful monitoring of potassium levels and renal function. Prospective controlled trials of ACE inhibitors alone and in combination with spironolactone added to conventional therapy should be performed to determine the lowest effective doses and to predict which patients will benefit most from combined therapy.