DISSOCIATION BETWEEN EXERTIONAL SYMPTOMS AND CIRCULATORY FUNCTION IN PATIENTS WITH HEART-FAILURE

Background Patients with heart failure frequently report exertional dy spnea and fatigue. These symptoms are usually attributed to circulator y dysfunction and therefore are typically treated with cardiovascular medications. Serial assessment of exertional symptoms has also become the principal method used to assess drug efficacy in heart failure. Ne vertheless, the relation between exertional symptoms in heart failure and circulatory dysfunction remains uncertain. Methods and Results Thi s study was undertaken to investigate the relation between exertional symptoms, ventilatory and skeletal muscle dysfunction, and circulatory function in patients with heart failure. To this end, 52 ambulatory p atients with heart failure underwent hemodynamic monitoring during max imal treadmill exercise testing. During exercise, the severity of dysp nea and fatigue was evaluated on a scale of 6 to 20 (Borg scale). The level of perceived exercise intolerance during daily activities was ev aluated with the Minnesota Living With Heart Failure Questionnaire and the Yale Dyspnea-Fatigue Index. Maximal treadmill exercise increased the VO2 to 13.4+/-2.8 mL . min(-1) . kg(-1), the dyspnea score to 15.7 +/-2.3, the fatigue score to 1.4.8+/-3.4, the pulmonary wedge pressure to 28+/-11 mm Hg, and the pulmonary artery lactate concentration to 3 4.5+/-16.3 mg/dL and decreased the pulmonary artery hemoglobin oxygen saturation to 30+/-9%. The level of perceived dyspnea had no relation to the pulmonary wedge pressure and correlated only minimally with the level of excessive ventilation (r=.39). The level of perceived fatigu e correlated only weakly with blood lactate concentration (r=.55). Ele ven patients (21%) exhibited a normal cardiac output and wedge pressur e <20 mm Hg during exercise, 22 (42%) exhibited a normal cardiac outpu t but wedge pressure >20 mm Hg during exercise, and 19 (37%) exhibited reduced cardiac output and wedge pressure >20 mm Hg during exercise. Despite these markedly different hemodynamic responses, all three grou ps exhibited similar levels of fatigue and dyspnea at comparable workl oads and had comparable total scores for the Minnesota Living With Hea rt Failure Questionnaire and the Yale Dyspnea-Fatigue Index. There was no relation between the Living With Heart Failure Questionnaire and p eak exercise ire, and only a weak correlation between the Dyspnea-Fati gue Index and peak VO2 (r =.48). Conclusions The level of exercise int olerance perceived by patients with heart failure has little or no rel ation to objective measures of circulatory, ventilatory, or metabolic dysfunction during exercise. In patients who report severe exertional symptoms, it may be desirable to directly measure hemodynamic response to exercise to ensure that these symptoms are due to circulatory dysf unction.