Does left atrial volume affect exercise capacity of heart transplant recipients?

Abstract

Background: Heart transplant (HT) recipients demonstrate limited exercise capacity compared to normal patients, very likely for multiple reasons. In this study we hypothesized that left atrial volume (LAV), which is known to predict exercise capacity in patients with various cardiac pathologies including heart failure and hypertrophic cardiomyopathy is associated with limited exercise capacity of HT recipients.

Methods: We analyzed 50 patients [age 57 ±2 (SEM), 12 females] who had a post-HT echocardiography and cardiopulmonary exercise test (CPX) within 9 weeks time at clinic follow up. The change in LAV (ΔLAV) was also computed as the difference in LAV from the preceding one-year to the study echocardiogram. Correlations among the measured parameters were assessed with a Pearson's correlation analysis.

Results: LAV (n = 50) and ΔLAV (n = 40) indexed to body surface area were 40.6 ± 11.5 ml·m-2 and 1.9 ± 8.5 ml·m-2·year-1, data are mean ± SD, respectively. Indexed LAV and ΔLAV were both significantly correlated with the ventilatory efficiency, assessed by the VE/VCO2 slope (r = 0.300, p = 0.038; r = 0.484, p = 0.002, respectively). LAV showed a significant correlation with peak oxygen consumption (r = -0.328, p = 0.020).

Conclusions: Although our study is limited by a retrospective study design and relatively small number of patients, our findings suggest that enlarged LAV and increasing change in LAV is associated with the diminished exercise capacity in HT recipients and warrants further investigation to better elucidate this relationship.

Figure 1

Study design. The study design is shown. Left atrial volume (LAV) was calculated from baseline echocardiography and the volume change in LAV (ΔLAV) was calculated from the baseline LAV subtracted that at the preceding one year. CPX = cardiopulmonary stress test.

Figure 2

Relationship between left atrial volume and ventilatory efficiency. The linear correlation between left atrial (LA) volume in panel A or yearly change in LA volume (ΔLA) volume with ventilatory efficiency (VE/VCO₂ slope) in panel B is shown. The correlation was analyzed with the Pearson product moment correlation.