Although a recent trial investigated patients with low EF and HF at the time of MI (reference number 4), there are no studies that specifically address use of ARBs in asymptomatic patients with reduced LVEF. However, given the results of studies in symptomatic patients with low EF, ARBs may be an appropriate alternative, particularly in patients who cannot tolerate an ACEI.
Furthermore, although controlled clinical trials are lacking, the use of beta-blockers in patients with a low ejection fraction and no symptoms (especially those with coronary artery disease) is also warranted7.
In contrast, there are no data to recommend the use of digoxin in patients with asymptomatic LV dysfunction, with the exception of those with atrial fibrillation. Because the only reason to treat such patients is to prevent the progression of HF, and because digoxin has minimal effect on disease progression in symptomatic patients, it is unlikely that the drug would be beneficial in those with no symptoms8.
Likewise, there are no data to recommend the routine use of calcium channel blockers in patients with asymptomatic reduction of LVEF. Nonetheless, since calcium channel blockers have not been shown to have adverse effects, they may be helpful for concomitant conditions such as hypertension. Caution should be used in the utilization of calcium channel blockers with negative inotropic effects, which are not recommended in asymptomatic patients with EF less than 40% after MI9.
Physicians should pay particular attention to patients whose cardiomyopathy is associated with a rapid arrhythmia of supraventricular origin (e.g., atrial flutter or atrial fibrillation). Although physicians frequently consider such tachycardias to be the result of an impairment of ventricular function, these rhythm disorders may lead to or exacerbate the development of a cardiomyopathy10. Therefore, in patients with a depressed left ventricular ejection fraction, every effort should be made to control the ventricular response to these tachyarrhythmias or to restore sinus rhythm.
Finally, in patients with severe valvular disease (severe aortic or mitral valve stenosis or regurgitation), but no symptoms valve replacement or repair surgery should be considered even when ventricular function is impaired. Long-term treatment with a systemic vasodilator drug may be considered for those with severe aortic regurgitation who are deemed to be poor candidates for surgery. Several studies have suggested that
7 Vantrimpont P, Rouleau JL, Wun CC, et al. Additive beneficial effects of beta-blockers to angiotensin- converting enzyme inhibitors in the Survival and Ventricular Enlargement (SAVE) Study. SAVE Investigators. J Am Coll Cardiol 1997;29:229-36.
8 The effect of digoxin on mortality and morbidity in patients with heart failure. The Digitalis Investigation Group. N Engl J Med 1997;336:525-33.
9 The Multicenter Diltiazem Postinfarction Trial Research Group. The effect of diltiazem on mortality and reinfarction after myocardial infarction. N Engl J Med 1988;319:385-92.
10 Grogan M, Smith HC, Gersh BJ, Wood DL. Left ventricular dysfunction due to atrial fibrillation in patients initially believed to have idiopathic dilated cardiomyopathy. Am J Cardiol 1992;69:1570-3.