Elsevier

JACC: Cardiovascular Imaging

Volume 16, Issue 9, September 2023, Pages 1163-1177
JACC: Cardiovascular Imaging

Original Research
Subendocardial Involvement as an Underrecognized LGE Subtype Related to Adverse Outcomes in Hypertrophic Cardiomyopathy

https://doi.org/10.1016/j.jcmg.2023.03.011Get rights and content

Abstract

Background

Late gadolinium enhancement (LGE) has been established as an independent predictor for adverse outcomes in hypertrophic cardiomyopathy (HCM). However, the prevalence and clinical significance of some LGE subtypes have not been well demonstrated.

Objectives

In this study, the authors sought to investigate the prognostic value of subendocardium-involved LGE pattern and location of right ventricle insertion points (RVIPs) with LGE in HCM patients.

Methods

In this single-center retrospective study, 497 consecutive HCM patients with LGE confirmed by cardiac magnetic resonance (CMR) were included. Subendocardium-involved LGE was defined as LGE involving subendocardium not corresponding to a coronary vascular distribution. Subjects with ischemic heart disease that would contribute to subendocardial LGE were excluded. Endpoints included a composite of heart failure–related events, arrhythmic events, and stroke.

Results

Of the 497 patients, subendocardium-involved LGE and RVIP LGE were observed in 184 (37.0%) and 414 (83.3%), respectively. Extensive LGE (≥15% of left ventricular mass) was detected in 135 patients. During a median follow-up of 57.9 months, 66 patients (13.3%) experienced composite endpoints. Patients with extensive LGE had a significantly higher annual incidence of adverse events (5.1% vs 1.9% per year; P < 0.001). However, spline analysis showed that the association between LGE extent and HRs for adverse outcomes tended to be nonlinear. The risk of composite endpoint increased with percentage increase in LGE extent in patients with extensive LGE, whereas a similar trend was not observed in patients with nonextensive LGE (<15%). In patients with extensive LGE, LGE extent significantly correlated with composite endpoints (HR: 1.05; P = 0.03) after adjusting for left ventricular ejection fraction <50%, atrial fibrillation, and nonsustained ventricular tachycardia, whereas in patients with nonextensive LGE, subendocardium-involved LGE rather than LGE extent was independently associated with adverse outcomes (HR: 2.12; P = 0.03). RVIP LGE was not significantly associated with poor outcomes.

Conclusions

In HCM patients with nonextensive LGE, the presence of subendocardium-involved LGE rather than LGE extent is associated with unfavorable outcomes. Given that the prognostic value of extensive LGE has been broadly recognized, subendocardial involvement as an underrecognized LGE pattern shows the potential to improve risk stratification in HCM patients with nonextensive LGE.

Section snippets

Study population

We retrospectively evaluated 1,055 patients diagnosed with HCM by means of CMR from June 2012 to June 2014. All patients were assessed by 12-lead or 24-hour Holter electrocardiography and echocardiography within 2 weeks before CMR. HCM was diagnosed by increased LV wall thickness (≥15 mm or ≥13 mm with family history) that is not solely explained by abnormal loading conditions.7,12 Exclusion criteria were: 1) absence of LGE (n = 314); 2) recognized myocardial infarction (MI), defined as a

Demographic and clinical characteristics

The baseline characteristics of patients are presented in Table 1. Figure 3A shows the distribution of study patients with different LGE extents. According to LGE extent with a cutoff of 15%, the cohort was dichotomized into extensive LGE (n = 135; age: 45.4 ± 12.2 years; 87 men) and nonextensive LGE (n = 362; age: 45.9 ± 13.5 years; 252 men). Patients with extensive LGE had more severe symptoms (NYHA functional class III or IV) (20.7% vs 12.4%; P < 0.02) and higher rates of atrial fibrillation

Discussion

In this study, we retrospectively collected HCM patients and explored the prognostic value of LGE in 3 aspects: LGE extent, subendocardium-involved LGE pattern, and RVIP LGE location. The main findings were as follows: 1) the risk of cardiovascular events occurrence rises with percentage increase in LGE extent in HCM patients with extensive LGE (≥15%), but this trend was not observed in patients with nonextensive LGE (<15%); 2) in HCM patients with nonextensive LGE, subendocardium-involved LGE

Conclusions

The risk of cardiovascular events increases with percentage increase in LGE extent in HCM patients with extensive LGE (≥15%). Instead of LGE extent, the subendocardium-involved LGE pattern, an underrecognized phenotype in HCM, is related to the adverse outcomes in HCM patients with nonextensive LGE (<15%), especially for HF-related outcomes. RVIP LGE is commonly seen in HCM but does not have prognostic value.

COMPETENCY IN MEDICAL KNOWLEDGE: Given that the prognostic value of extensive LGE has

Funding Support and Author Disclosures

This study was supported by grant number 2021YFF0501400 and 2021YFF0501404 from the National Key Research and Development Program of China and grant number 81930044 from the Key Projects of the National Natural Science Foundation of China. The funding sources had no role in the design and conduct of the study, collection, management, analysis, and interpretation of the data, preparation, review, or approval of the manuscript, and decision to submit the manuscript for publication. The authors

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    ∗

    Drs Yang and Zhao contributed equally to this work as first authors.

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    © 2023 by the American College of Cardiology Foundation. Published by Elsevier.