Hypertrophic cardiomyopathy (HCM) is a common inherited cardiac disease characterized by varying degrees of left ventricular outflow tract obstruction. In a large cohort, we compare the outcomes among 3 different hemodynamic groups. We prospectively enrolled patients fulfilling standard diagnostic criteria for HCM from January 2005 to June 2015. Detailed phenotypic characterization, including peak left ventricular outflow tract pressure gradients at rest and after provocation, was measured by echocardiography. The primary outcome was a composite cardiovascular end point, which included new-onset atrial fibrillation, new sustained ventricular tachycardia/ventricular fibrillation, new or worsening heart failure, and death. The mean follow-up was 3.4±2.8 years. Among the 705 patients with HCM (mean age, 52±15 years; 62% men), 230 with obstructive HCM were older and had a higher body mass index and New York Heart Association class. The 214 patients with nonobstructive HCM were more likely to have a history of sustained ventricular tachycardia/ventricular fibrillation and implantable cardioverter defibrillator implantation. During follow-up, 121 patients experienced a composite cardiovascular end point. Atrial fibrillation occurred most frequently in the obstructive group. Patients with nonobstructive HCM had more frequent sustained ventricular tachycardia/ventricular fibrillation events. In multivariate analysis, obstructive (hazard ratio, 2.80; 95% confidence interval, 1.64-4.80) and nonobstructive (hazard ratio, 1.94; 95% confidence interval, 1.09-3.45) HCM were associated with more adverse events compared with labile HCM. Nonobstructive HCM carries notable morbidity, including a higher arrhythmic risk than the other HCM groups. Patients with labile HCM have a relatively benign clinical course. Our data suggest detailed sudden cardiac death risk stratification in nonobstructive HCM and monitoring with less aggressive management in labile HCM.

Objective

Hypertensive response to exercise (HRE) is observed in patients with hypertrophic cardiomyopathy (HCM) with normal resting blood pressure (BP). However, the prevalence or prognostic implications of HRE in HCM remain unclear.

Methods

In this study, normotensive HCM subjects were enrolled. HRE was defined as systolic BP > 210 mmHg in men or >190 mmHg in women, or diastolic BP > 90 mmHg, or an increase in diastolic BP > 10 mmHg during treadmill exercise. All participants were followed for subsequent development of hypertension, atrial fibrillation (AF), heart failure (HF), sustained ventricular tachycardia/fibrillation (VT/VF), and all-cause death. Six hundred and eighty HCM patients were screened.

Results

347 patients had baseline hypertension, and 333 patients were baseline normotensive. 132 (40%) of the 333 patients had HRE. HRE was associated with female sex, lower body mass index and milder left ventricular outflow tract obstruction. Exercise duration and metabolic equivalents were similar between patients with or without HRE, but the HRE group had higher peak heart rate (HR), better chronotropic response and more rapid HR recovery. Conversely, non-HRE patients were more likely to exhibit chronotropic incompetence and hypotensive response to exercise. After a mean follow-up of 3.4 years, patients with and without HRE had similar risks of progression to hypertension, AF, HF, sustained VT/VF or death.

Conclusion

HRE is common in normotensive HCM patients during exercise. HRE did not carry higher risks of future hypertension or cardiovascular adverse outcomes. Conversely, the absence of HRE was associated with chronotropic incompetence and hypotensive response to exercise.