Impairment of exercise capacity and peak oxygen consumption in patients with mild left ventricular dysfunction and coronary artery disease.

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Abstract
Aims Most studies in chronic heart failure have only included patients with marked left ventricular systolic dysfunction (i.e. ejection fraction ≤0·35), and patients with mild left ventricular dysfunction are usually excluded. Further, exercise capacity strongly depends on age, but age-adjustment is usually not applied in these studies. Therefore, this study sought to establish whether (age-adjusted) peak Vo2was impaired in patients with mild left ventricular dysfunction. Methods Peak Vo2and ventilatory anaerobic threshold were measured in 56 male patients with mild left ventricular dysfunction (ejection fraction 0·35–0·55; study population) and in 17 male patients with a normal left ventricular function (ejection fraction >0·55; control population). All patients had an old (>4 weeks) myocardial infarction. By using age-adjusted peak Vo2values, a ‘decreased’ exercise capacity was defined as ≤ predicted peak Vo2−1×SD (0·81 of predicted peak Vo2), and a severely decreased exercise capacity as ≤ predicted peak Vo2−2×SD (0·62 of predicted peak Vo2). Results Patients in the study population (age 52±9 years; ejection fraction 0·46±0·06) were mostly asymptomatic (NYHA class I; n=40, 76%), while 16 patients (24%) had mild symptoms, i.e. NYHA class II. All 17 controls (age 57±8 years) were asymptomatic. Mean peak Vo2was lower in patients with mild left ventricular dysfunction (23·6±5·7 vs 27·1±4·6ml.min−1.kg−1in controls,P2was decreased (NYHAI/II: n=29/13) and in 18% of them severely decreased (n=10; NYHAI/II: n=6/4). In contrast, only three patients (18%) in the control population had a decreased and none a severely decreased age-adjusted peak Vo2. Conclusion In patients with mild left ventricular dysfunction, who have either no or only mild symptoms of chronic heart failure, a substantial proportion has an impaired exercise capacity. By using age-adjustment, impairment of exercise capacity becomes more evident in younger patients. Patients with mild left ventricular dysfunction are probably under-diagnosed, and this finding has clinical and therapeutic implications.The European Society of Cardiology

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