Mortality in Young Patients With Hypertrophic Cardiomyopathy
Have changes in management strategies over the last two decades altered the mortality rate for young patients with hypertrophic cardiomyopathy (HCM)?
A retrospective review was performed at two major HCM tertiary referral centers. A total of 474 consecutive HCM patients between 7 and 29 years of age were studied over 7.1 ± 5.1 years.
Over the course of the study period, 452 patients (95%) survived. HCM-related sudden death (SD) occurred in 18 patients (3%; 0.54% per year): arrhythmic SD (n = 12), progressive heart failure and heart transplant complications (n = 5), or postoperatively (n = 1). Aborted life-threatening events occurred in 63 other high-risk patients (13%), resuscitated out-of-hospital cardiac arrest (n = 20), or heart transplant for advanced heart failure (n = 12). When including only HCM-related deaths, 5- and 10-year survival were 97% and 94%, respectively. These outcomes are similar to those previously reported in middle-aged HCM patients (98% and 94%, p = 0.23). Approximately one half of the patient population had undergone implantable cardioverter-defibrillator (ICD) placement (total of 231 patients of which 212 were implanted for primary prevention and 19 for secondary prevention). Inappropriate ICD shocks occurred in 18% of patients.
The authors concluded that low mortality rates can be achieved in young patients with HCM with application of contemporary cardiovascular treatment strategies.
This study reports overall quite good intermediate-term outcomes in young patients with HCM. Historically, young patients have been thought to be at greatest risk for complications of HCM, particularly SD. At the core of the treatment strategy for these patients was the uniform application of a risk stratification scheme advanced in the United States/Canada (American Heart Association/American College of Cardiology) consensus guidelines. To review, these included the presence of one or more major risk factors including family history of SD due to HCM in ≥1 first- or second-degree relative, unexplained recent syncope, massive left ventricular hypertrophy (wall thickness ≥30 mm), multiple repetitive nonsustained ventricular tachycardia on ambulatory electrocardiography monitoring, and hypotensive or blunted blood pressure response to exercise. Although there was a significant burden of inappropriate shocks, ICD therapy was life-saving in a significant number of patients. The currently applied risk stratification model was good but not perfect, as three patients died suddenly without apparent risk markers.
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