Do hemodynamic indices correlate with maximum exercise capacity and oxygen consumption in chronic congestive heart failure

The mechanism of exercise intolerance in chronic congestive heart failure remains unclear. We correlated resting haemodynamic variables with the peak exercise capacity and maximum oxygen consumption (VO2 max) in patients with congestive heart failure in 27 studies on treadmill exercise testing using the modified Bruce protocol. VO2 max was measured using breath by breath expiratory gas analysis. The patients were in severe congestive heart failure (NYHA class II and III, pulmonary artery wedge pressure 23 +/- 2 mmHg, cardiac index 2.4 +/- 0.21 l/min/m2). VO2 max was 23 +/- 2 ml/kg/min. Fatigue was the commonest symptom limiting the exercise. None of the hemodynamic variables correlated well with VO2 max. [right atrial pressure (r = 0.08), pulmonary artery pressure (r = 0.05), pulmonary artery wedge pressure (r = 0.08), aortic pressure (r = -0.3) & cardiac index (r = 0.29)]. Both uni- and multi-variate analysis failed to show any relation between VO2 max and resting hemodynamic variables. We conclude that unlike the acute heart failure syndromes, resting hemodynamic variables do not correlate with exercise capacity in patients with chronic congestive heart failure. The abnormal resting haemodynamics do not limit exercise in these patients. Peripheral mechanisms may thus be more important.