HEMODYNAMIC PERFORMANCE DURING EXERCISE IN PATIENTS WITH SEVERE CHRONIC CONGESTIVE-HEART-FAILURE BEFORE AND AFTER A SINGLE-DOSE OF PIMOBENDAN

Duration of symptom-limited exercise on a bicycle ergometer (constant workload of 25 W) was determined in 12 patients with severe chronic co ngestive heart failure (CHF) due to dilated cardiomyopathy (CMP, 4 pat ients) or ischemic heart disease (IHD, 8 patients) undergoing hemodyna mic monitoring. Mean exercise duration was 214 +/- 124 s and produced severe dyspnea lasting > 5 min in all patients. The next morning, each patient exercised again to the same level; pimobendan (10 mg orally) was then administered, and exercise to the same workload was repeated 4 and 10 h later. Mean +/- SD exercise-induced changes in heart rate ( HR, min(-1)), pulmonary capillary wedge pressure (PCW, mm Hg), cardiac output (CO, L/min(-1)), and stroke volume index (SVI, ml.min(-1)) wer e as follows. At baseline, HR was 85 +/- 17-110 +/- 21 beats/min (p < 0.001), PCW 21 +/- 10-31 +/- 10 mm Hg (p < 0.05), CO 3.7 +/- 1.0-3.9 /- 1.0 L.min(-1) (NS), and SVI, 25 +/- 7-20 +/- 7 ml.m(-2) (NS). Four hours after pimobendan administration, HR was 90 +/- 14-113 +/- 21 bea ts/min (p < 0.001), PCW 11 +/- 7-20 +/- 10 mm Hg (p < 0.05), CO 5.3 +/ - 0.7-5.8 +/- 1.0 L.min(-1)(NS), and SVI 33 +/- 3-29 +/- 7 ml.m(-2) (N S). Ten h after pimobendan, HR was 89 +/- 17-113 +/- 21 beats/min Cp < 0.05), PCW 14 +/- 7-24 +/- 7 mm Hg (p < 0,001), CO 5.4 +/- 0.7-5.4 +/ - 1.4 L.min(-1) (NS), and SVI 34 +/- 7-27 +/- 10 ml.m(-2)(NS). Hemodyn amic variables at rest improved markedly after pimobendan; the decreas e in PCW and the increases in CO and in SVI were highly significant (p < 0.0001). Pimobendan decreased severity and duration of exertional d yspnea. Increases in HR and in PCW during exercise were similar before and after pimobendan; CO and SVI did not increase during ergometry.