Impact of peak provoked left ventricular outflow tract gradients on clinical outcomes in hypertrophic cardiomyopathy

Background Hypertrophic cardiomyopathy (HCM) is traditionally classified based on a left ventricular outflow tract (LVOT) pressure gradient of 30 mmHg at rest or with provocation. There are no data on whether 30 mmHg is the most informative cut-off value and whether provoked gradients offer any information regarding outcomes. Methods Resting and provoked peak LVOT pressure gradients were measured by Doppler echocardiography in patients fulfilling guidelines criteria for HCM. A composite clinical outcome including new onset atrial fibrillation, ventricular tachycardia/fibrillation, heart failure, transplantation, and death was examined over a median follow-up period of 2.1 years. Results Among 536 patients, 131 patients had resting LVOT gradients greater than 30 mmHg. Subjects with higher resting gradients were older with more cardiovascular events. For provoked gradients, a bi-modal risk distribution was found. Patients with provoked gradients > 90 mmHg (HR 3.92, 95% CI 1.97–7.79) or < 30 mmHg (HR 2.15, 95% CI 1.08–4.29) have more events compared to those with gradients between 30 and 89 mmHg in multivariable analysis. The introduction of two cut-off points for provoked gradients allowed HCM to be reclassified into four groups: patients with “benign” latent HCM (provoked gradient 30–89 mmHg) had the best prognosis, whereas those with persistent obstructive HCM had the worst outcome. Conclusions Provoked LVOT pressure gradients offer additional information regarding clinical outcomes in HCM. Applying cut-off points at 30 and 90 mmHg to provoked LVOT pressure gradients further classifies HCM patients into low-, intermediate- and high-risk groups.