Characteristics and Longer-Term Outcomes of Contemporary Patients <18 Years of Age with Hypertrophic Cardiomyopathy.
We describe characteristics and outcomes of contemporary pediatric hypertrophic cardiomyopathy (PHC) patients. We studied 398 consecutive pediatric HC patients (<18 years, median 14 years, 65% boys) seen at our center between 2002-2018. Baseline clinical and pediatric echocardiographic data was collected. Left ventricular outflow tract gradient (LVOTG), LV fractional shortening and Z-score for left ventricular (LV) wall thickness were calculated. Sudden cardiac death (SCD), appropriate internal defibrillator discharge (ICD), myectomy and orthotopic heart transplant (OHT) were composite primary endpoint. 133 (33%) had symptoms [71 (18%) dyspnea, 77 (19%) angina and 19 (5%) syncope], 109 (27%) were on betablockers; 179 (45%) had family history of HC. 146 (37%) underwent genetic testing [of which 91 (62%) were HC-gene positive]. Basal septal LV thickness, septal LV z-score and fractional shortening were 1.2±0.6 cm, 4.8±5.6 & 42%±8, while 23% had extreme LV hypertrophy (z-score>6) and 8% had LVOTG >30 mm Hg (range 0-139 mm Hg). At a median of 5.9 years [interquartile range 2.4, 9], there were 23 (6%) ICD’s placed and 47 (12%) primary composite events [9 (2%) deaths, 3 (1%) appropriate ICD discharge, 29 (7%) myectomy and 8 (2%) OHT]. There were no in hospital deaths following myectomy/OHT. Presence of symptoms (Hazard ratio or HR 2.45), ventricular tachycardia (HR 1.52) and higher basal septal LV z-score (HR 1.10) were independently associated with primary composite outcomes. LV septal z-score >4 was independently associated with events on spline analysis. Rate of SCD/appropriate ICD discharge was 0.5%/year. In conclusion, contemporary PHC patients seen at an experienced center have excellent outcomes with presence of symptoms and higher LV septal thickness associated with primary composite events.