Effect of obesity on myocardial tissue characteristics in patients with hypertrophic cardiomyopathy: a cardiovascular magnetic resonance-based study.

BACKGROUND

Obesity is associated with cardiac steatosis in healthy adults and is independently associated with increased left ventricular (LV) mass and could contribute to the progression of heart failure-related composite events in patients with hypertrophic cardiomyopathy (HCM). However, it is unclear whether the increased LV mass is accompanied by increased fibrosis. We aimed to assess the impact of increased body mass index (BMI) on myocardial tissue characteristics in patients with HCM.

METHODS

A total of 737 patients with HCM (99 obese, 298 overweight, and 340 normal-weight patients) who underwent cardiovascular magnetic resonance (CMR) imaging were prospectively included. We assessed the relationship between BMI and LV mass, global native T1, extracellular volume, and late gadolinium enhancement (LGE) using CMR. Myocardial tissues from one patient each with obstructive HCM who underwent septal myectomy of the obese, overweight, and normal-weight groups were obtained and stained with red oil O, hematoxylin, and Masson's trichrome.

RESULTS

LV mass index (87.2, interquartile range [IQR]: 71.3 to 113.8, 89.4, IQR:75.5 to 111.5, and 104.7, IQR: 86.4 to 123.4 g/m2, P < 0.001) was higher in obese and overweight patients with HCM than those with normal weight, but the native T1 was decreased in obese patients with HCM (1324±67 ms, 1308±63 ms, and 1298±67 ms, P < 0.001). In addition, there was no significant difference in LGE extent among the three subgroups (normal weight: 3.7%, IQR: 0 to 9.5%, overweight: 2.7%, IQR: 0 to 7.7%, obese: 3.8%, IQR: 0 to 7.2%, P = 0.194). Multivariable linear regression analyses found that BMI was independently associated with global native T1 (β = -1.918, P = 0.005). Furthermore, myocardial tissues stained with oil red O from three patients showed an increasing extent of fat deposits with BMI, whereas collagen volume fractions were similar.

CONCLUSION

In HCM patients, obesity is associated with increased myocardial mass and decreased native T1, likely reflecting cardiac steatosis in addition to fibrosis. This distinction underscores the potential reversibility of obesity-related myocardial changes through targeted weight management.

TRIAL REGISTRATION: This prospective cohort study was registered in the Chinese Clinical Trial Registry (URL: http://www.chictr.org.cn; Registry number: ChiCTR1900024094).