Influence of Myocardial Fibrosis on Left Ventricular Hypertrophy in Patients with Symptomatic Severe Aortic Stenosis

Abstract

Aim: It was the aim of our study to determine whether myocardial fibrosis influences physiologic or non-physiologic left ventricular (LV) hypertrophy in severe aortic stenosis. Methods: Myocardial fibrosis was evaluated using specimens taken from the ventricular septum in 79 patients submitted to aortic valve replacement because of symptomatic aortic stenosis. Patients were considered to have physiologic LV hypertrophy if end-systolic wall stress, evaluated by echocardiography, was <90 kdyn/cm², while those with end-systolic wall stress >90 kdyn/cm² were considered to have non-physiologic hypertrophy. Results: Fibrosis tissue mass index was significantly inversely related with LV fractional shortening and directly related with LV diastolic and systolic diameter and LV mass index (LVMI). Patients with non-physiologic hypertrophy (n = 24) had a higher LVMI due to larger LV diastolic and systolic diameters with thinner wall, resulting in lower relative wall thickness. These patients had a higher fibrosis tissue mass index and impaired LV systolic and diastolic functions, as suggested by lower LV fractional shortening and higher mean wedge pressure. At follow-up of 7.4 ± 2.1 months, the LVMI and New York Heart Association class remained higher in patients with non-physiologic hypertrophy. Conclusions: Our study suggests a different quality of hypertrophies in patients with aortic stenosis, where myocardial fibrosis seems to be the critical abnormality that differentiates adaptive from maladaptive response to increased afterload.