IMPAIRMENT OF EXERCISE CAPACITY AND PEAK OXYGEN-CONSUMPTION IN PATIENTS WITH MILD LEFT-VENTRICULAR DYSFUNCTION AND CORONARY-ARTERY DISEASE

Aims Most studies in chronic heart failure have only included patients with marked left ventricular systolic dysfunction (i.e. ejection frac tion less than or equal to 0.35), and patients with mild left ventricu lar dysfunction are usually excluded. Further, exercise capacity stron gly depends on age, but age-adjustment is usually not applied in these studies. Therefore, this study sought to establish whether (age-adjus ted) peak Vo(2) was impaired in patients with mild left ventricular dy sfunction. Methods Peak Vo(2) and 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; con trol population). All patients had an old (>4 weeks) myocardial infarc tion. By using age-adjusted peak Vo(2) values, a 'decreased' exercise capacity was defined as less than or equal to predicted peak Vo(2) - 1 x SD (0.81 of predicted peak Vo(2)), and a severely decreased exercis e capacity as less than or equal to predicted peak Vo(2) - 2 x SD (0.6 2 of predicted peak Vo(2)). Results Patients in the study population ( age 52 +/- 9 years; ejection fraction 0.46 +/- 0.06) were mostly asymp tomatic (NYHA class I; n=40, 76%), while 16 patients (24%) had mild sy mptoms, i.e. NYHA class II. All 17 controls (age 57 +/- 8 years) were asymptomatic. Mean peak Vo(2) was lower in patients with mild left ven tricular dysfunction (23.6 +/- 5.7 vs 27.1 +/- 4.6 ml.min(-1).kg(-1) i n controls, P<0.05). In 75% of the study population patients (n=42) ag e-adjusted peak Vo(2) was decreased (NYHA I/II: n=29/ 13) and in 18% o f them severely decreased (n=10; NYHA I/ II: n=6/4). In contrast, only three patients (18%) in the control population had a decreased and no ne a severely decreased age-adjusted peak Vo(2). Conclusion In patient s with mild left ventricular dysfunction, who have either no or only m ild symptoms of chronic heart failure, a substantial proportion has an impaired exercise capacity. By using age-adjustment, impairment of ex ercise capacity becomes more evident in younger patients. Patients wit h mild left ventricular dysfunction are probably under-diagnosed, and this finding has clinical and therapeutic implications.