# Left ventricular longitudinal function is reduced but partially compensated by increased radial function after heart transplantation

## TL;DR

Heart transplant recipients have reduced left ventricular longitudinal function, partially compensated by increased lateral function, but this does not affect exercise capacity or resting cardiac output.

## Contribution

This study is the first to show altered left ventricular mechanics in heart transplant patients and their lack of association with clinical outcomes like exercise capacity.

## Key findings

- Heart-transplanted patients had significantly reduced LVAVPD and longitudinal contribution to stroke volume compared to controls.
- Lateral wall contribution to stroke volume was increased in heart-transplanted patients.
- Longitudinal function was not associated with exercise capacity or resting cardiac output in these patients.

## Abstract

In healthy hearts, left ventricular atrioventricular plane displacement (LVAVPD) measured by cardiac magnetic resonance (CMR) contributes to ∼60% of stroke volume. LVAVPD has been shown to correlate with maximal cardiac output and exercise capacity and is an independent predictor of outcomes in patients with heart failure. We aimed to assess if longitudinal pumping is altered, if LVAVPD is associated with exercise capacity, and if any difference in longitudinal pumping could be explained by the presence of a right bundle branch block (RBBB) in heart-transplanted patients.

This single-center study included 34 heart-transplanted patients who had undergone CMR and a cardiopulmonary exercise test as part of a clinical post-transplant surveillance program. Data was compared to 34 healthy sex- and age-matched controls.

Heart-transplanted patients had decreased LVAVPD (10.3 vs 13.7 mm, p < 0.01), lower longitudinal contribution (46% vs 53%, p < 0.01), and lower septal contribution (−3% vs 8%, p < 0.01) to stroke volume compared to controls. Furthermore, the lateral contribution was increased (44% vs 28%, p < 0.01) in the heart-transplanted patients. Longitudinal contribution to stroke volume was neither associated with exercise capacity (p = 0.20) nor cardiac output at rest (p = 0.62). There was no difference in LVAVPD in patients with and without RBBB (p = 0.81).

Heart-transplanted patients have decreased left ventricular longitudinal function compared to healthy controls, in part compensated by an augmented lateral function. Longitudinal function is not associated with cardiac output at rest or exercise capacity in this patient group. Whether the altered pumping mechanics seen are associated with outcome remains to be investigated.