Left ventricular mass including papillary muscles and trabeculations has greater prognostic value compared with maximum left ventricular wall thickness in hypertrophic cardiomyopathy

Background

Traditionally, maximum left ventricular (LV) wall thickness (MLVWT) has been the principal imaging marker for prognostication in hypertrophic cardiomyopathy (HCM). However, LV mass may be a better measure of overall burden of hypertrophy in HCM and better reflect prognosis. Differing methods of measuring LV mass may also impact its prognostic value. This study aimed to compare the prognostic value of LV mass compared to maximum LVWT and establish the preferred method for measuring LV mass by cardiovascular magnetic resonance (CMR) imaging.

Methods

Consecutive HCM patients undergoing CMR in 2012–2024 were analyzed. LV mass indexed to body surface area was measured either including or excluding papillary muscles and trabeculations (LVMIinc and LVMIexc, respectively). The MLVWT was derived from the highest value measured at all 16 segments of the LV. The primary endpoint was HCM-related events, defined as a composite of sudden cardiac death (SCD) events, heart failure (HF) events, stroke, and cardiovascular death.

Results

In 1045 patients (median age 58, IQR 48–67 years; male 68.3%), 91 (8.7%) experienced the primary endpoint over a median follow-up of 3.2 (IQR 1.4–6.0) years. LVMIinc (median 108.5, IQR 90.2–130.3 g/m2) was approximately 38% higher than LVMIexc[이1] (median 78.4, IQR 64.6–83.2 g/m2), and was moderately correlated to MLVWT (R=0.688, p<0.001). LV mass, especially LVMIinc, showed the greater discriminative performance for the primary endpoint compared to MLVWT, though modest, with similar performance in men and women. ROC-derived optimal cutoff for LVMIinc was 110 g/m², in both men and women. Increased LVMIinc (≥110 g/m²) was independently associated with the primary endpoint, after adjustment for age, sex, and important imaging variables, such as peak LV outflow tract gradient, LV ejection fraction, degree of fibrosis measured by late gadolinium enhancement (LGE%) and extracellular volume fraction (ECV%), and MLVWT. Meanwhile, MVLWT was not significantly associated with the primary endpoint in multivariable analysis. Exploratory analyses suggested that the prognostic value of LVMI and MLVWT was diminished in patients with extensive LGE, and that lower MLVWT was associated with higher risk of the primary endpoint in these patients.

Conclusion

LV mass was a better predictor of HCM-related outcomes than MLVWT in patients with HCM and has incremental prognostic value over parameters of LV systolic function, fibrosis, peak gradient, and MLVWT. LV mass should be measured including papillary muscles and trabeculation in HCM patients, as this method better predicts outcome.

[이1]Greater difference than the general population, approx. 12%For image description, please refer to the figure legend and surrounding text.For image description, please refer to the figure legend and surrounding text.