The effect of beta-adrenergic blockers on the prognostic value of peak exercise oxygen uptake in patients with heart failure.

OBJECTIVES

Our aim was to determine the effect of beta-adrenergic blockade on the prognostic value of peak oxygen consumption testing in patients with heart failure.

BACKGROUND

Peak oxygen consumption has been shown to be a useful prognostic tool in patients with heart failure. However, studies demonstrating the utility of peak oxygen consumption were conducted before beta-blocker therapy became widespread. Thus, our objective was to determine the effect of beta-blockers on the prognostic value of peak oxygen consumption in patients with heart failure.

METHODS

Actuarial, anthropomorphic, hemodynamic and exercise ventilatory data were collected from 369 patients with heart failure. Death and orthotopic heart transplants were the events tracked. Patients were divided into those taking beta-blockers and those not taking them. Event-free survival days were calculated.

RESULTS

One hundred ninety-nine patients on beta-blockers and 170 not on beta-blockers were studied. There were 40 orthotopic heart transplants and 82 deaths during follow-up. Peak oxygen consumption (milliliters per kilogram per minute) trended toward being an independent predictor of event-free survival (p = 0.055). In patients on and not on beta-blockers, a peak oxygen consumption of >14 ml/kg.min was associated with a 1-year event rate of approximately half of that associated with a peak oxygen consumption </=14 ml/kg x min. However, for every level of peak oxygen consumption, the event rate was lower in the group taking beta-blockers.

CONCLUSIONS

Beta-blocker status does not change the predictive power of peak oxygen consumption in patients with heart failure, but beta-blocker status is important to consider when using peak oxygen consumption to predict event-free survival in patients with heart failure.