Left ventricular diastolic function assessed with cardiovascular magnetic resonance imaging and exercise capacity in patients with non-obstructive hypertrophic cardiomyopathy

Introduction

In patients with non-obstructive hypertrophic cardiomyopathy (HCM) and preserved left ventricular (LV) systolic function, diastolic dysfunction is one of the major factors contributing to limited exercise capacity.

Purpose

To assess the usefullness of simple cardiovascular magnetic resonance (CMR) parameters of LV diastolic function at rest and exercise capacity in patients with non-obstructive HCM and preserved LV systolic function.

Methods

The study included 13 patients who underwent cardiopulmonary exercise testing on treadmill and CMR within 1 month distance. Analyzed parameters of diastolic function included: atrio-ventricular plane descent (AVPD), sphericity index (SI), left ventricular mass index (LVMI), peak filling rate normalized to LV stroke volume index (PFR/LVSVI) and time from the end-systole to PFR normalized to heart rhythm (TPFR).

Results

There was a significant correlation between PFR/LVSVI at rest and peak oxygen uptake (V0₂peak) (r = 0.64, p = 0.02). Patients with V0₂peak below median (<30 ml/kg/min) had a significantly lower PFR/LVSVI then patients with higher V0₂peak [5.12 m²/s, interquartile range (IQR) 4.16–6.82 vs. 7.93 m²/s, IQR 7.49–8.21 respectively, p = 0.035). AVPD, SI, LVMI, TPFR were not related to exercise capacity. There was also no correlation between V0₂peak and age (r = -0.38, p = 0.19), LV ejection fraction (r = -0.36, p = 0.22) or normalized LV volume indices: LVEDVI (r = 0.09, p = 0.76), LVESVI (r = 0.34, p = 0.26).

Conclusion

Assessment of LV diastolic function by peak filling rate normalized to stroke volume index with means of CMR at rest in patients with non-obstructive hypertrophic cardiomyopathy and preserved LV systolic function is a usefull predictor of exercise capacity. It can be added to CMR study protocols of HCM patients.