Noninvasive assessment of cardiac pumping capacity during exercise predicts prognosis in patients with congestive heart failure.

BACKGROUND

Prognostic parameters in patients with congestive heart failure (CHF) are important for guiding therapeutic options. Maximal oxygen uptake (O(2)max) is a widely used parameter for prognostic assessment in patients with CHF and correlates with exercise cardiac output; however, afterload is not taken into account.

METHODS

The concept of a noninvasive surrogate of cardiac power output combines exercise systolic BP (SBP), as an estimate of afterload, with O(2)max, as an estimate of exercise cardiac output neglecting preload. Thus, a variable termed exercise cardiac power (ECP) is defined as the product of O(2)max (expressed as a percent predicted value) and SBP (ECP, expressed as %mm Hg, is the product of O(2)max, expressed as percentage of predicted maximum, times systolic pressure. The prognostic value of ECP obtained during routine treadmill ergospirometry was assessed in patients referred to our heart failure clinic. Patients undergoing heart transplantation were censored at the time of transplantation.

RESULTS

One hundred fifty-four patients were followed prospectively for a mean (+/- SE) duration of 625 +/- 32 days. Thirty-two patients (21%) died. ECP was the most powerful predictor of mortality, was the combined end point of mortality or hospitalization for worsening heart failure (all p < 0.001), and was an independent predictor in multivariate analysis. An ECP of < 5,000 %mm Hg indicated a poor prognosis with a 1-year mortality rate of 37%, whereas only 2% of the patients having an ECP of > 9,000 %mm Hg died during the first year.

CONCLUSION

The integration of afterload and O(2)max improves the prognostic value of each indicator, and provides an easily available and independent predictor of mortality and morbidity in CHF patients. This integrative concept of cardiac hydraulic performance is superior to O(2)max and can be used in routine ergospirometry.