# Left atrial function is a strong predictor of exercise intolerance in patients with hypertrophic cardiomyopathy

## TL;DR

This study shows that left atrial function is a key factor in exercise intolerance among patients with hypertrophic cardiomyopathy.

## Contribution

The study identifies left atrial reservoir strain as an independent predictor of exercise capacity in HCM patients.

## Key findings

- 77.8% of HCM patients had reduced exercise tolerance based on Peak VO2 measurements.
- Left atrial reservoir strain was an independent predictor of Peak VO2, outperforming LA diameter and volumes.
- LV ejection fraction, volume, strain, and outflow tract pressure gradient were not significantly associated with exercise capacity.

## Abstract

Patients with hypertrophic cardiomyopathy (HCM) often experience exercise intolerance. However, the primary determinants of exercise capacity in patients with HCM remain unclear.

This study aimed to evaluate exercise intolerance in patients with HCM and investigate the associations between exercise capacity and clinical/imaging characteristics, specially focusing on left atrial (LA) function.

This retrospective analysis utilized data from a prospective cohort of adult patients with HCM. Included patients underwent standardized cardiopulmonary exercise testing (CPET) and 3.0T cardiac magnetic resonance (CMR) between May 2012 and May 2025. Exercise capacity was primarily assessed by peak oxygen uptake (Peak VO2) measured during CPET. LA function (diameter, volumes and strain) was evaluated using CMR. Univariable and multivariable linear regression analyses were used to identify determinants of exercise capacity.

Among 120 participants [60.8% (73/120) male, mean age: 45.5 ± 14.4 years], 77.8% (91/120) had reduced exercise tolerance (Peak VO2 < 80% of the predicted normal value). The mean value of Peak VO2 was 20.6 ± 5.6 mL/min/kg. Lower Peak VO2 correlated with older age, female gender, larger LA size and reduced LA strain. Notably, LV ejection fraction, volume, strain, and outflow tract pressure gradient showed no significant associations (all P value >0.05). Besides, multivariate analysis identified LA reservoir strain as an independent predictor of Peak VO2 (β = 0.275, P < 0.001), outperforming LA diameter and volumes.

LA dysfunction, as reflected by reduced strain, independently predicts impaired exercise capacity in HCM.