Muscular exercise capacity and body fat predict VO(2peak) in heart transplant recipients.

BACKGROUND: Heart transplant (HTx) recipients usually have reduced exercise capacity, with reported VO2peak levels of 50-70% of predicted values. This study aimed to evaluate central and peripheral factors predictive of VO2peak. METHODS AND RESULTS: Fifty-one clinically stable HTx recipients >18 years old and 1-8 years after HTx, underwent maximal exercise testing on a treadmill. Clinical laboratory, haemodynamic and echocardiographic data, lung function, and isokinetic muscle strength and muscular exercise capacity were recorded. The mean ± SD age was 52 ± 16 years, 71% were male, and time from HTx was 4.1 ± 2.2 years. The patients were assigned to one of two groups: VO2peak ≤or >27.3 ml/kg/min, which was the median value, corresponding to 80% of predicted value. The group with the higher VO2peak had significantly lower body mass index, body fat, and triglycerides, and significantly higher body water, muscular exercise capacity, high-density lipoprotein (HDL) cholesterol, lung function, mitral annular velocity, peak ventilation, O2 pulse, and VE/VCO2 slope. Donor age, recipient age, sex, medication, ischaemic time, cardiac dimensions, systolic function, and chronotropic responses during exercise were similar. Multiple regression analysis showed that muscular exercise capacity and body fat were the strongest VO2peak predictors. CONCLUSIONS: Chronotropic incompetence is not a limiting factor for exercise capacity in a population of relatively fit HTx patients. The most significant predictors, representing only peripheral factors, are similar to those often determining VO2peak in healthy, non-athletic individuals. Our findings emphasize the importance of a low percentage of body fat and high muscular exercise capacity in order to attain a sufficient VO2peak level after HTx.

Effect of high-intensity interval training on progression of cardiac allograft vasculopathy.

BACKGROUND: Cardiac allograft vasculopathy (CAV) is a progressive form of atherosclerosis occurring in heart transplant (HTx) recipients, leading to increased morbidity and mortality. Given the atheroprotective effect of exercise on traditional atherosclerosis, we hypothesized that high-intensity interval training (HIIT) would reduce the progression of CAV among HTx recipients. METHODS: Forty-three cardiac allograft recipients (mean ± SD age 51 ± 16 years; 67% men; time post-HTx 4.0 ± 2.2 years), all clinically stable and >18 years old, were randomized to either a HIIT group or control group (standard care) for 1 year. The effect of training on CAV progression was assessed by intravascular ultrasound (IVUS). RESULTS: IVUS analysis revealed a significantly smaller mean increase [95% CI] in atheroma volume (PAV) of 0.9% [95% CI -;0.3% to 1.9%] in the HIIT group as compared with the control group, 2.5% [1.6% to 3.5%] (p = 0.021). Similarly, the mean increase in total atheroma volume (TAV) was 0.3 [0.0 to 0.6] mm(3)/mm in the HIT group vs 1.1 [0.6 to 1.7] mm(3)/mm in the control group (p = 0.020), and mean increase in maximal intimal thickness (MIT) was 0.02-0.01 to 0.04] mm in the HIIT group vs 0.05 [0.03 to 0.08] mm in the control group (p = 0.054). Qualitative plaque progression (virtual histology parameters) and inflammatory activity (biomarkers) were similar between the 2 groups during the study period. CONCLUSIONS: HIIT among maintenance HTx recipients resulted in a significantly impaired rate of CAV progression. Future larger studies should address whether exercise rehabilitation strategies should be included in CAV management protocols.

Aerobic interval training versus continuous moderate exercise after coronary artery bypass surgery: a randomized study of cardiovascular effects and quality of life.

BACKGROUND: Peak oxygen uptake (Vo(2peak)) strongly predicts mortality in cardiac patients. We compared the effects of aerobic interval training (AIT) versus moderate continuous training (MCT) on Vo(2peak) and quality of life after coronary artery bypass grafting (CABG). METHODS: Fifty-nine CABG patients were randomized to either AIT at 90% of maximum heart rate or MCT at 70% of maximum heart rate, 5 d/wk, for 4 weeks at a rehabilitation center. Primary outcome was Vo(2peak), at baseline, after rehabilitation (4 weeks), and after 6 months of home-based exercise (6 months). RESULTS: Vo(2peak) increased between baseline and 4 weeks in AIT (27.1 +/- 4.5 vs 30.4 +/- 5.5 mL.kg(-1).min(-1), P < .001) and MCT (26.2 +/- 5.2 vs 28.5 +/- 5.6 mL.kg(-1).min(-1), P < .001; group difference, not significant). Aerobic interval training increased Vo(2peak) between 4 weeks and 6 months (30.4 +/- 5.5 vs 32.2 +/- 7.0 mL.kg(-1).min(-1), P < .001), with no significant change in MCT (28.5 +/- 5.6 vs 29.5 +/- 5.7 mL.kg(-1).min(-1)). Quality of life improved in both groups from baseline to 4 weeks, remaining improved at 6 months. There were no changes in echocardiographic systolic and diastolic left ventricular function. Adiponectin increased between 4 weeks and 6 months in both groups (group differences, not significant). CONCLUSIONS: Four weeks of intense training increased Vo(2peak) significantly after both AIT and MCT. Six months later, the AIT group had a significantly higher Vo(2peak) than MCT. The results indicate that AIT and MCT increase Vo(2peak) similarly in the short term, but with better long-term effect of AIT after CABG.