Lung function and cardiopulmonary exercise performance after heart transplantation - Influence of cardiac allograft vasculopathy

Study objective: The reduced exercise capacity observed in most patients af ter heart transplantation may be clue to treatment with immunosuppressive d rugs, deconditioning, cardiac denervation, and graft rejection. Cardiac all ograft vasculopathy (CAV) is presently the major factor limiting long-term survival after transplantation. Little information is available with regard to the relationship between CAV and functional impairment in these patient s. Design: Prospective. Setting: A university hospital and a large transplant center. Patients: About 37 +/- 5 months (range, 2 to 137 months) after orthotopic h eart transplantation, 120 patients underwent lung function testing, cardiop ulmonary exercise testing, and right and left heart catheterization. Signif icant CAV was defined as a stenosis greater than or equal to 70% or severe diffuse obliteration in any of the three main vessels. Group I (n = 28) had a significant CAV; group II (n = 92), without a remarkable CAV, was the co ntrol group. Measurements and results: Overall, the maximum heart rate was 86 +/- 2% of what was predicted, and the peak oxygen consumption was 18.8 +/- 0.7 mL/kg/ min (64% of that predicted). Groups I and II did not show significant diffe rences with regard to anthropometric data, hemodynamic measurements, or num ber of rejection episodes. Group I exhibited significant differences in max imum heart rate (120 +/- 5 vs 134 +/- 3 beats/min; p < 0.01), work capacity (47 +/- 5% vs 59 +/- 3%; p < 0.05), peak oxygen uptake (16 +/- 1 vs 20 +/- 1 mL/min/kg; p < 0.01), and functional dead space ventilation (31 +/- 2 vs 26 +/- 1; p < 0.01). Pretransplant status, etiology of heart failure, isch emic time, and the number of rejection episodes did not correlate with any exercise parameter. Conclusions: Following heart transplantation, patients with significant CAV show a diminished exercise capacity, a reduced oxygen uptake, and a ventil ation-perfusion mismatch. Thus, CAV may be a major factor limiting exercise capacity in heart-transplant patients.