Eric Decoulx

Kinetics of oxygen consumption during and after exercise in patients with dilated cardiomyopathy. New markers of exercise intolerance with clinical implications.

OBJECTIVES This study analyzed the kinetics of oxygen consumption during and after a maximal cardiopulmonary exercise test in patients with dilated cardiomyopathy. The prognostic information derived from indexes of recovery was also studied. BACKGROUND Previous studies have examined the kinetics of oxygen consumption during a short recovery period in a limited number of patients. To our knowledge, no study has examined the prognostic information derived from indexes of recovery. METHODS We studied 153 patients and 55 control subjects. We calculated the ratio between total oxygen consumption during exercise and recovery, the half-recovery time of peak oxygen consumption, the time constant of recovery, the recovery time and the ratio between duration of exercise and recovery time. RESULTS Recovery of oxygen consumption was significantly delayed in patients, and this delay was related to the degree of exercise intolerance. After a median follow-up period of 439 days, for the total study group, percent of predicted peak oxygen consumption (p = 0.003) and ejection fraction (p = 0.03) were independent predictors of survival. In a subgroup of patients with moderate exercise intolerance (percent peak oxygen consumption > 40%), the ratio between total oxygen consumption during exercise and recovery (p = 0.013) and the ejection fraction (p = 0.013) were independent predictors of survival. CONCLUSIONS The kinetics of oxygen consumption during recovery was delayed in patients with dilated cardiomyopathy. Although indexes of recovery were not prognostic markers in the total study group, the ratio between total oxygen consumption during exercise and recovery was an independent prognostic marker in patients with moderate exercise intolerance.

Comparative Diagnostic Value of Ankle-to-Brachial Index and Transcutaneous Oxygen Tension at Rest and After Exercise in Patients with Intermittent Claudication

Background: Few studies have compared sensitivities of ankle-to-brachial index (ABI) and transcutaneous oxygen tension (TcPO2) in a large group of patients with Leriche stage II intermittent claudication. Method and Results: 111 patients (138 limbs) with a stable chronic (> three months) intermittent claudication and significant peripheral vascular disease (PVD) proved by angiography were studied. They performed a treadmill test (10%, 3 km/hr) limited by limb pain. ABI and TcPO2 were measured before, just after exercise, and after three and ten minutes of recovery in supine position. Sensitivities per patient for ABI and TcPO2 were respectively at rest: 82.9% and 28.8%, and after exercise: 88.3% and 62.2%. Sensitivities per leg (n=138) for ABI and TcPO2 were respectively at rest: 73.9% and 26.8%, and after exercise: 82.6% and 34%. The sensitivity of TcPO2 increased to 56.5% after three minutes of recovery but was always less than that of ABI, which was maximal just after exercise (82.6%). The sensi tivity of the regional perfusion index was similar to that of TcPO2. The sensitivity of TcPO2 increased with respect to the Leriche stage and the number of lesions but was always lower than that of ABI. There was a weak correlation between TcPO2 and ABI after exercise, but no correlation was noted between maximal walking distance, ABI, and TcPO2. Conclusion: TcPO 2 is not required in patients with Leriche stage II intermittent clau dication but might be useful either in severely affected patients (Leriche stage III or IV) or in selected patients.

Plasma levels of endothelin-1 at rest and after exercise in patients with moderate congestive heart failure

Plasma levels of endothelin-1 are increased in patients with severe congestive heart failure related to various etiologies. However, conflicting data have been published in patients with moderate congestive heart failure. Moreover, the effect of exercise on plasma levels of endothelin-1 is not precisely known. We determined the plasma levels of endothelin-1 in a homogenous group of patients with idiopathic dilated cardiomyopathy in stage II of the New York Heart Association functional classification at rest and at peak exercise. In this group of patients, plasma levels of endothelin-1 were increased compared to a control group (2.9 +/- 0.27 vs. 1.96 +/- 0.24 pmol/l, P < 0.01, mean +/- S.E.M.), as were plasma levels of atrial natriuretic peptide (26.3 +/- 6.3 vs. 2.95 +/- 0.7 pmol/l, P < 0.001), plasma renin activity (12.6 +/- 2.98 vs. 1.75 +/- 0.23 ng/ml per h, P < 0.001) and plasma levels of aldosterone (217 +/- 29.3 vs. 154 +/- 18.8 pg/ml, P < 0.05). In contrast to the other hormones, exercise did not increase plasma levels of endothelin-1. There was no correlation between plasma levels of endothelin-1 and plasma levels of atrial natriuretic peptide, and no correlation between left ventricular ejection fraction, peak oxygen consumption and hormonal values. In conclusion, plasma levels of endothelin-1 are increased in a homogeneous group of patients with idiopathic dilated cardiomyopathy and moderate congestive heart failure. Endothelin-1 could participate in the progression of heart failure. Exercise did not increase the plasma levels of endothelin-1 in contrast to the other hormones.