Hemodynamic Effects of Exercise Training in Heart Failure

Background: Exercise performance improvement after training in heart failure (HF) can be due to central or peripheral changes. Methods and Results: In 70 HF stable patients we measured peak VO2 and cardiac output (CO, inert gas rebreathing technique) and calculated arteriovenous O-2 differences (a-v O(2)diff) before and after an 8-week training program. Peak VO2 changed from 1111 +/- 403 mL/minute to 1191 +/- 441 (P < .001), peak workload from 68 +/- 29 watts to 76 +/- 32 (P < .0001), peakCO from 6.6 +/- 2.2 L/minute to 7.3 +/- 2.5 (P < .0001), and peak a-v O(2)diff from 17.5 +/- 5.1 mL/100 mL to 16.6 +/- 4.1 (P = .081). Changes in peak CO and a-v O(2)diff allowed to identify 4 behaviors: group 1: (n = 15) reduction in peak CO and increase in a-v O(2)diff (peak VO2 unchanged, peak workload +9.5%); group 2: (n = 16) both peak CO and a-v O(2)diff increased as well as peak VO2 (23%) and workload (18%); group 3: (n = 4) peak CO and a-v O(2)diff reduced as well as peak VO2 (-18%) and workload (-5%); group 4: (n = 35) peak CO increased with a-v O(2)diff reduced (increase in peak VO2 by 5.5 and workload by 8.4%). Conclusions: Exercise training improves peakVO(2) by increasing CO with unchanged a-v O(2)diff. A reduction after training of a-v O(2)diff with an increase in CO is frequent (50% of cases), is suggestive of blood flow redistribution and, per se, not a sign of reduced muscle performance been associated with improved exercise capacity. (J Cardiac Fail 2011;17:916-922)