Clinical Implications of Midventricular Obstruction in Patients With Hypertrophic Cardiomyopathy
What are the prevalence, prognosis, and clinical characteristics of hypertrophic cardiomyopathy (HCM) patients with midventricular obstruction (MVO)?
The study cohort was comprised of 490 HCM patients. Left ventricular MVO was diagnosed when the peak midcavitary gradient was estimated to be >30 mm Hg.
The study investigators identified MVO in 9.4% (n = 46 patients). Patients with MVO were more likely to be symptomatic than those without. They found MVO to be an independent determinant of HCM-related death in multivariate models (hazard ratio [HR], 2.23; p = 0.016), and this trend was especially pronounced for the combined endpoint of sudden death and potentially lethal arrhythmic events (HR, 3.19; p < 0.001). They identified apical aneurysm formation in 28.3% of patients with MVO and strongly predicted HCM-related death (HR, 3.47; p = 0.008) and the combined endpoint of sudden death and potentially lethal arrhythmic events (HR, 5.08; p < 0.001). In addition, MVO without apical aneurysm was also identified as an independent determinant of the combined endpoint of sudden death and potentially lethal arrhythmic events (HR, 2.43; p = 0.045).
The analysis identified MVO as an independent predictor of adverse outcomes, especially the combined endpoint of sudden death and potentially lethal arrhythmic events. These results suggest that longer periods of exposure to MVO might lead to unfavorable consequences. They also support the principle that the presence of MVO in patients with HCM has important pathophysiological implications.
This is an important study because it better defines the natural history in a subset of patients with HCM. Further studies are needed to determine how best to detect, monitor, and treat MVO in patients with HCM.
Keywords: Prognosis, Cardiomyopathy, Hypertrophic, Heart Failure, Death, Sudden, Cardiac
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