Dilated-hypokinetic evolution of hypertrophic cardiomyopathy: prevalence, incidence, risk factors, and prognostic implications in pediatric and adult patients

Abstract

Objectives: This study sought to investigate the incidence, risk factors, and prognosis of dilated-hypokinetic evolution in a large cohort of patients with hypertrophic cardiomyopathy (HCM) followed up at a cardiology center serving both the pediatric and the adult population.

Background: The available data on this evolution of HCM mainly regards prevalence (rather than incidence) in adults, with very little being known about the pediatric population.

Methods: A total of 222 consecutive HCM patients (65% men, 19% < or =18 years old) were prospectively evaluated for a mean follow-up of 11 +/- 9 years.

Results: A diagnosis of dilated-hypokinetic HCM was made in 12 patients at first evaluation (11 without previous septal myectomy surgery; prevalence, 4.9%). Twelve of the 210 patients with classic HCM at first evaluation underwent dilated-hypokinetic evolution (incidence, 5.3/1,000 patient-years). Patients with prevalent/incident dilated-hypokinetic evolution were younger at first evaluation (32 +/- 14 years vs. 41 +/- 21 years, p = 0.04) and more often had a family history of HCM (61% vs. 26%, p = 0.002) or sudden death (43% vs. 19%, p = 0.01) with respect to patients who maintained classic HCM. Moreover, they showed greater interventricular septum (23 +/- 3 mm vs. 19 +/- 6 mm, p = 0.004) and posterior wall (15 +/- 3 mm vs. 13 +/- 4 mm, p = 0.006) thickness. Cardiovascular death-free survival was lower among patients with dilated-hypokinetic HCM (p < 0.04). Cox proportional hazards regression analysis identified left ventricular wall thickness (hazard ratio [HR] = 1.07; 95% confidence interval [CI], 1.01 to 1.14; p = 0.03) and end-diastolic diameter (HR = 1.08; 95% CI 1.04 to 1.11; p = 0.0001) as independent predictors of cardiovascular death.

Conclusions: Dilated-hypokinetic evolution is rare but not exceptional in HCM. Young age at diagnosis, family history of HCM, and greater wall thickness are incremental risk factors for dilated-hypokinetic HCM, which carries an ominous prognosis.