Prognostic impact of ventilatory efficiency in heart disease patients with preserved exercise tolerance

Abstract

Background: The minute ventilation/carbon-dioxide output (V̇E/V̇CO2) slope as a marker of cardiac events has been established in patients with severe heart failure, but it is not known whether it is useful for other heart diseases. Methods and Results: The present study investigated 215 patients with various heart diseases (age 59±11 years; ischemic heart disease, n=89; dilated cardiomyopathy, n=38; valvular disease, n=37; hypertensive heart disease, n=33; others, n=18) who underwent cardiopulmonary exercise testing to determine the V̇E/V̇CO2 slope. Patients were divided into 2 groups according to the V̇E/ V̇CO2 slope and were followed-up for 3 years. Forty-eight cardiac events (6 deaths, 42 re-hospitalizations) occurred during the observation period. Patients with a V̇E/V̇CO2 slope >34 had a significantly higher 3-year cardiac event rate (32.1%) than patients with V̇E/V̇CO2 slope <34 (18.9%, p<0.05). When patients were selected with relatively preserved peak oxygen uptake values (>16 ml·kg-1·min-1), patients with V̇E/V̇CO2 slope >34 still demonstrated a significantly higher cardiac event rate than other patients (35.0% vs 13.3%, p<0.01). Conclusion: The V̇E/V̇CO2 slope may be a prognostic indicator of cardiac events in a heterogeneous group of patients with heart disease, independent of exercise tolerance.