E/e′ ratio and outcome prediction in hypertrophic cardiomyopathy: the influence of outflow tract obstruction

Aims: Diastolic dysfunction is thought to be an important pathophysiologic component of hypertrophic cardiomyopathy (HCM). However, there are conflicting data on the potential value of the mitral E/e' ratio. We examined whether left ventricular outflow tract (LVOT) obstruction influences the value of E/e' in predicting outcomes in HCM. Methods and results: Patients who met diagnostic criteria for HCM were enrolled. Diastolic function was assessed with complete two-dimensional and Doppler echocardiography. A composite clinical outcome including new onset atrial fibrillation, sustained ventricular tachycardia/fibrillation, heart failure, transplantation, and death was examined over a mean follow-up period of 4.2 years. Among 604 patients, 206 patients had an E/e' level ≥20. Patients with higher septal E/e' level were older, with more severe NYHA class, and more severe LVOT obstruction. Higher E/e' was associated with worse event-free survival in non-obstructive group and total HCM cohort. In addition, E/e' and LVOT pressure gradient were highly correlated in non-obstructive and total HCM, but not in labile or obstructive group. During follow-up period, 95 patients underwent myectomy. Post-op E/e' correlated significantly with LVOT pressure gradient (R = 0.306, P = 0.004). In these patients, post-op E/e' was associated with worse event-free survival (log-rank P = 0.030). Conclusion: Assessment of E/e' is useful for risk stratification in HCM patients. Nevertheless, the predictive power is confounded by dynamic LVOT obstruction. Higher E/e' predicts worse clinical outcomes in non-obstructive HCM and in labile/obstructive after myectomy.