The extensive body of data regarding the use of P receptor antagonists in chronic heart failure provides compelling evidence that P antagonists improve symptoms, reduce hospitalization, and decrease mortality in patients with mild and moderate heart failure. Accordingly, P receptor antagonists are now recommended for routine use in patients with an ejection fraction <35% and NYHA Class II or III symptoms in conjunction with ACE inhibitor or angiotensin receptor antagonist, and diuretics as required to palliate symptoms.
This general recommendation should be tempered by certain limitations in the experimental database. First, most of the data that underlie this recommendation were obtained in relatively stable patients with mild-to-moderate symptoms. Therefore, the role of P receptor antagonists in patients with more severe symptoms, or with recent decompensation, is not yet clear. Likewise, the utility of b receptor blockade in patients with asymptomatic left ventricular dysfunction has not been studied. Finally, although it appears likely that the beneficial effects of these drugs are related to b receptor blockade, it cannot be assumed that all b receptor antagonists will exert similar effects. Since b antagonists have the potential to worsen both ventricular function and symptoms in patients with heart failure, several caveats should be considered. b Adrenergic receptor antagonists should be initiated at very low doses, generally less than one-tenth of the final target dose, and the dose should be increased slowly, over the course of weeks and under careful supervision. The rapid institution of the usual b adrenergic receptor—blocking doses used for hypertension or coronary artery disease may cause decompensation in many patients who otherwise would be able to tolerate a slower dose titration. Even when therapy is initiated with low doses of a b antagonist, there may be an increased tendency to retain fluid that will require adjustments in the diuretic regimen. Although limited data suggest that patients with NYHA Class IIIB and IV CHF may tolerate b blockers and benefit from their use, this group of patients should be approached with considerable caution. There is almost no experience in patients with new-onset, recently decompensated heart failure. Such patients should not be treated with b blockers until after they have stabilized for several days to weeks.
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