Real-world applicability of a risk prediction score in apical hypertrophic cardiomyopathy

Introduction

In alignment with latest evidence, apical hypertrophic cardiomyopathy (aHCM) is no longer considered a benign subtype of HCM, with current guideline-recommend risk stratification tools possibly underestimating risk in this subset of patients.

Purpose

To assess the real-world applicability of a recently proposed aHCM-specific risk prediction score.

Methods

Patients followed at a dedicated HCM clinic with previous diagnosis of aHCM were included. HCM phenocopies were excluded. Clinical, analytical and imaging data were extracted from medical records review. A recently proposed aHCM-specific risk prediction score (figure 1) was then applied, with higher scores indicating greater risk of adverse events at follow-up. The primary composite endpoint included death, sustained ventricular arrhythmias or appropriate implantable cardioverter-defibrillator (ICD) therapies and advanced heart failure.

Results

From an initial cohort of 165 HCM pts, 30 pts with established aHCM were included. Pts were predominantly male (n=18, 60%) with mean age 57±18 years and one-fourth was genotype-positive (n=7, 23.3%). The majority had preserved left ventricle systolic ejection fraction (n=29, 96.7%), with mean left atria index volume (LAVi) 54±35 mL/m2 and mean right ventricle systolic pressure (RVSP) 29±6 mmHg.

3.3% (n=1) had an apical aneurysm and 45.8% (n=11) had extensive late gadolinium enhancement. More than-half (n=19, 63.3%) had a concomitant diagnosis of atrial fibrillation.

Relying on baseline data, the aHCM-specific risk score could be calculated in only 26.7% (n=8) of our cohort, mainly due to missing data on left atria index volume and right ventricle systolic pressure. Among these 8 aHCM pts, 3 (37.5%) were classified as score 0, 1 (12.5%) as score 1, 1 (12.5%) as score 2, and 3 (37.5%) as score ≥3.

Over a mean follow-up time of 7±5 years, 6.7% (n=2) implanted an ICD in the setting of SCD primary prevention, while 16.7% (n=5) experienced the primary composite endpoint.

Among patients with a calculable risk score, the primary composite endpoint was observed in 1 (12.5%) – an individual with a score of 2; no other events were observed in the remaining categories, including in the 3 patients with score ≥ 3.

Conclusion

In our real-world cohort, a meaningful proportion of patients met the primary endpoint, reinforcing the non-benign nature of aHCM. However, the application of the aHCM-specific risk score was feasible in only a minority, largely due to incomplete availability of key echocardiographic parameters, limiting the assessment of its prognostic performance in our cohort. These findings highlight the challenges to routine implementation and the need for standardized imaging protocols to enhance risk scores application.For image description, please refer to the figure legend and surrounding text.