Phenotype, genotype and prognosis of apical hypertrophic cardiomyopathies: a French multicentric cohort.

AIMS: Apical hypertrophic cardiomyopathies (ApHCM) are characterized by hypertrophy located on the left ventricular (LV) apical segments. Their genetic origin and prognosis are still debated. We compared the phenotype, genotype and prognosis of ApHCM to non-apical HCM.

METHODS AND RESULTS: 208 consecutive patients from 5 French centres with a phenotype of ApHCM underwent echocardiography, cardiac magnetic resonance, genetic testing and follow-up. They were compared with 419 patients with non-apical HCM. Patients finally diagnosed with Fabry's disease (n = 6) and amyloidosis (n = 1) were excluded, resulting in 201 ApHCM for comparative analyses. Among the 208 ApHCM patients, genetic analysis was positive in 22.6% of patients, including 6 GLA and 1 TTR mutations. After excluding these latter 7 patients, ApHCM patients had higher LVEF, less LV obstruction (5% vs. 23.2%, P < 0.001), smaller left atrial volumes (37.9 ± 14.2 vs. 47.2 ± 23.8 mL/m2, P < 0.001), more impaired GLS (-14.4 ± 4 vs. -15.3 ± 4%, P = 0.019), more frequent LV aneurysm (10.9% vs. 1.4%, P < 0.001), and less frequent mutations (20.4% vs. 43.4%, P < 0.001) than non-apical HCM. During a 5-year follow-up, 12 (6%) rhythmic events occurred in the ApHCM group. All of them had a SCD-risk score <4%. Long-term survival was better in ApHCM (P = 0.026).

CONCLUSION: ApHCM presents with less frequent mutations and better prognosis than non-ApHCM. However, rhythmic complications are frequent in ApHCM but are not predicted by the SCD-risk score. Apical aneurysms are more frequent in apical HCM. Fabry's disease may mimic an apical HCM phenotype and should be ruled out when facing an apical HCM pattern.