Abstract 19976: Flow Mediated Dilatation is Responsible For Abnormal Blood Pressure Response on Exercise in Patients With Hypertrophic Cardiomyopathy and Syncope
Introduction: Hypertrophic Cardiomyopathy (HCM) is an inherited myocardial disease characterized by unexplained increased left ventricular wall thickness associated with non-dilated ventricular chambers. Syncope and pre-syncope occur in approximately 15-25% of patients with HCM. Either arrhythmias or transient haemodynamic impairment (abnormal blood pressure response on exercise and ventricular outflow tract obstruction) are considered the underlying mechanism of syncope in HCM patients. Nevertheless the endothelial function is crucial for the maintenance of vascular tone, therefore the vessel dilates in response to an increased blood flow through the vessel itself (flow-mediated dilatation - FMD).
Hypothesis: To assess the role of FMD in abnormal blood pressure response.
Methods: We studied 24 subjects (19 males and 5 females) affected by primitive genotyped HCM, mean age 40 years ± 12 years, over a median follow-up of 36 ± 7 months. At baseline every patient underwent physical examination, 12-lead ECG, trans-thoracic echocardiogram and magnetic resonance. Thereafter, at three-month interval, patients underwent 24-hour Holter monitoring, exercise stress test and a non-invasive study of endothelial function through a color-Doppler scan of brachial artery before and after ischemia provoked by arterial clamping.
Results: Syncopal episodes occurred in 10 patients on 24 (42%), 14 patients (58%) never fainted. The two groups were similar in clinical and genetic characteristics. Patients with syncope showed an abnormal blood pressure response on exercise and a three times higher FMD (15.3 mm vs 6.8 mm, p< 0.01). One patient had ventricular arrhythmias documented as leading cause of syncope. Four patients with syncope (40%) had an increased left ventricular outflow gradient whereas 6 patients (60%) without pathological gradient (at rest or provoked) had no documented cause.
Conclusions: In patients with HCM and syncope an abnormal peripheral dilatation after provoked ischemia seems to be responsible for abnormal blood pressure response on exercise and consequent syncope. Our experience demonstrate that FMD is a safe alternative to exercise stress test in detecting abnormal blood pressure response in HCM patients with syncope.
Author Disclosures: R. Morgagni: None. A. Capria: None. M. Perrone: None. A. Intorcia: None. F. Romeo: None.
- © 2016 by American Heart Association, Inc.