Echocardiographic assessment of right ventricular hypertrophy and right ventricular-pulmonary artery coupling in hypertrophic cardiomyopathy—implications for outcomes

Abstract

While the definition of hypertrophic cardiomyopathy (HCM) primarily focuses on left ventricular (LV) involvement, sarcomeric mutations cause similar myopathic abnormalities in both ventricles, with right ventricular (RV) hypertrophy being present in a significant number of cases. To a limited extent, the hypertrophied RV can compensate for the elevated afterload resulting from diastolic dysfunction and left intraventricular obstruction. Failure of adaptive RV remodeling marks the onset of RV-to-pulmonary artery (RV-PA) uncoupling. However, limited information is available regarding the relationship between echocardiographic surrogates of RV-PA coupling and HCM patient outcomes. Accordingly, in a large cohort of HCM patients, we explored the association of TAPSE/ pulmonary artery systolic pressure (PASP) and RV free wall shortening (RVFWS)/PASP ratios with a: (i) hard endpoint defined as the occurrence of either death, heart failure hospitalization, stroke, or sustained ventricular arrhythmias; (ii) soft endpoint defined by the occurrence of any of the previously mentioned events or new-onset atrial fibrillation. 224 HCM outpatients (58±18 years, 56% male) who underwent comprehensive echocardiographic evaluation were included. Within the study cohort, 176 (78%) presented RV hypertrophy, defined as an end-diastolic RV maximum wall thickness greater than 5 mm on either two- or three-dimensional echocardiographic datasets. There was a strong positive correlation between RV and LV maximum wall thickness (Pearson’s r=0.77, p<0.001). Patients with RV hypertrophy had significantly higher PASP values than those without (32±11 vs. 28±6 mmHg, p=0.002). The hard endpoint totaled 19 events, while the soft endpoint totaled 48 events. A multivariable logistic regression model including LV maximum wall thickness, LV global longitudinal strain, LV ejection fraction, and TAPSE/PASP selected this echocardiographic surrogate of RV-PA coupling as a significant, independent predictor of the hard endpoint (OR, 0.68; 95% CI, 0.53-0.8, p=0.002). A second multivariable logistic regression model including age, LV maximum wall thickness, LV global longitudinal strain, average E/e’ ratio, and TAPSE/PASP also confirmed TAPSE/PASP as a significant independent predictor of the soft endpoint (OR, 0.80; 95% CI, 0.68 – 0.94, p=0.009). In hierarchical chi-square analyses, the addition of RVFWS/PASP to the same baseline model (age, LV maximum wall thickness, LV global longitudinal strain, average E/e’ ratio) significantly increased the model’s predictive power for the hard endpoint (p value < 0.05) (Figure 1). In HCM patients, comprehensive assessment of right heart morphology and function has important prognostic implications and can further refine risk stratification.Figure 1.Hierarchical chi-square analyses