Cardiac allograft hypertrophy is associated with impaired exercise tolerance after heart transplantation

Background: Exercise performance, an important aspect of quality of life, remains limited after heart transplantation (HTx). This study examines the effect of cardiac allograft remodeling on functional capacity after HTx. Methods: The total cohort of 117 HTx recipients, based on echocardiographic determination of left ventricle mass and relative wall thickness at 1 year after HTx, was divided into 3 groups: (1) NG, normal geometry; (2) CR, concentric remodeling; and (3) CH, concentric hypertrophy. Cardiopulmonary exercise testing was performed 5.03 ± 3.08 years after HTx in all patients. Patients with acute rejection or significant graft vasculopathy were excluded. Results: At 1 year post-HTx, 30% of patients had CH, 55% had CR and 15% had NG. Exercise tolerance, measured by maximum achieved metabolic equivalents (4.62 ± 1.44 vs 5.52 ± 0.96 kcal/kg/h), normalized peak Vo ₂ (52 ± 14% vs 63 ± 12%) and Ve/Vco ₂ (41 ± 17 vs 34 ± 6), was impaired in the CH group compared with the NG group. A peak Vo ₂ ≤14 ml/kg/min was found in 6%, 22% and 48% of patients in the NG, CR and CH groups, respectively (p = 0.01). The CH pattern was associated with a 7.4-fold increase in relative risk for a peak Vo ₂ ≤14 ml/kg/min compared with NG patients (95% confidence interval 1.1 to 51.9, p = 0.001). After multivariate analysis, a 1-year CH pattern was independently associated with a reduced normalized peak Vo ₂ (p = 0.018) and an elevated Ve/Vco ₂ (p = 0.035). Conclusions: The presence of CH at 1 year after HTx is independently associated with decreased normalized peak Vo ₂ and increased ventilatory response in stable heart transplant recipients. The identification of CH, a potentially reversible mechanism of impairment in exercise capacity after HTx, may have major clinical implications.