Severe symptoms in mid and apical hypertrophic cardiomyopathy

Background: We analyzed the clinical and quantitative echocardiographic characteristics of patients with sub-basal hypertrophic cardiomyopathy (HCM) to define the characteristics of patients (pts) with severe symptoms. Methods: Of 444 pts in a referral-based HCM program, 22 (5%) had midventricular or apical HCM. Quality of life (QoL) questionnaire was administered as an independent confirmer of symptomatic state. Results: Ten pts were NYHA III and IV, and 12 pts were NYHA I and II; QoL scores (41 ± 26 vs. 10 ± 13, P = 0.001) confirmed a priori division of two groups based on NYHA classification. Pts with more severe symptoms were more likely female (70% vs. 25%, P = 0.001) with atrial fibrillation (40% vs. 0%, P = 0.02). They more frequently had midventricular HCM 60% versus 8% (P = 0.01) (mid-LV thickness 17 ± 6 vs. 12 ± 2 mm, P = 0.03) and had much smaller LV diastolic volumes 68 ± 12 versus 102 ± 22 ml (39 ± 4 vs. 53 ± 12 ml/m², P = 0.001). Septal E/E' was higher in the severely symptomatic pts (15 ± 5 vs. 7 ± 3, P = 0.001) indicating higher estimated LV filling pressure. Midobstruction with apical akinetic chamber was noted in 4/10 pts who developed refractory symptoms. Cardiac mortality was higher in the severely symptomatic patients, 4/10 who had midventricular HCM as compared to 0/12 in the mildly symptomatic apical HCM group (P = 0.03). Conclusions: In subbasal HCM, pts with severe symptoms have midventricular hypertrophy, with encroachment of the LV cavity and consequent very small LV volumes that may be complicated by mid-LV obstruction. Pts with mid-LV hypertrophy are more symptomatic than those with apical HCM, are often refractory to therapy, and have higher mortality.