Response of patients with coronary artery disease stratified by ejection fraction following short-term training

The purpose of this study was to investigate the response of patients with ischemic heart disease and varied left ventricular function following 6 weeks of exercise training. We studied the oxygen consumption (V o 2), and central hemodynamic and metabolic responses of 14 patients with coronary artery disease (CAD) stratified by left ventricular ejection fraction (EF). There were two groups of patients: normal EF (NEF), EF = 64 ± 9.9 (mean ± S.E.M.); n = 7, and diminished EF (DEF), EF = 36 ± 11.6; n = 7. The patients ranged in age from 42 to 72 years (54.9 ± 2.2), and were evaluated prior to and then following training. Measures of V o 2, cardiac output (Q t) stroke volume (SV), heart rate (HR), exercise duration (XTIME) and intensity (XI), as well as plasma lactate (LA), and the catecholamines epinephrine (E) and norepinephrine (NE) were obtained in response to maximal cycle ergometry. Subjects trained three times per week, 30 min per session, at an intensity equal to 70% of their peak oxygen consumption. Repeated measures analysis of variance (ANOVA) revealed no interaction between groups suggesting a similar training response. Significant post-training changes ( P < 0.05) were observed in peak V o 2 (V o 2peak) NEF, 11.8% increase, (16.0 ± 1.3 to 17.9 ± 1.1 ml/kg/min) and DEF, 9.3% increase (15.1 ± 1.6 to 16.5 ± 1.2 ml/kg/min); submaximal HR, 4% decrease in the NEF (95.57 ± 4.58 to 92 ± 4.43 beats/min) and a 6% decrease in the DEF (107.29 ± 7.44 to 101.43 ± 6.77 beats/min); XTIME NEF, 11.2% increase (7.8 ± 0.57 to 8.67 ± 0.61 min) and DEF, 16.6% increase (7.3 ± 0.91 to 8.51 ± 0.69 min); and XI NEF, 19.2% increase (104.3 ± 11.3 to 124.3 ± 12.9 W) DEF, 21.2% increase (94.3 ± 18.5 to 114.3 ± 16.9 W), and a 15% decrease in resting NE (350 ± 26 to 296.9 ± 19 pg/ml). There were no changes in Q t, SV, LA, E, peak NE or peak HR for either group. These findings suggest short-term endurance training at 70% V o 2peak provide the necessary stimulus for individuals with CAD and NEF or DEF to display an improvement in XI, XTIME, and V o 2peak. The lack of a significant enhancement in Q t with short-term training may indicate that the mechanism by which both study groups were able to attain significantly higher levels of V o 2peak may have been attributable to peripheral mechanisms rather than any alterations in Q t, a central mechanism.