Apical Sparing of Longitudinal Strain and Myocardial Fibrosis in Hypertensive Patients and Spontaneously Hypertensive Rats: Based on Speckle Tracking and Histological Analysis.

Abstract

BACKGROUND: This study aimed to investigate regional myocardial strain and fibrosis distribution to analyze the apical sparing pattern and the relation with hypertrophy in hypertension. METHODS: This study included clinical and experimental animal investigations. Seventy-three hypertensive patients were divided into two groups: hypertension without left ventricular hypertrophy (HT-NLVH) and hypertension with LVH (HT-LVH). Six 16-week-old male spontaneously hypertensive rats (SHR) and six age-matched male Wistar-Kyoto (WKY) rats were included in this experiment. Echocardiographic measurements were obtained. Myocardial strain indexes, including global longitudinal strain (GLS), the basal, middle, and apical segmental LS (LS-bas, LS-mid, LS-ap), and the proportion of LS-ap/(LS-bas&#x2009;+&#x2009;LS-mid&#x2009;+&#x2009;LS-ap) (P-ap) were measured. The histological collagen volume fraction (CVF) and perivascular collagen area (PVCA) of basal and apical segments (CVF-bas, CVF-ap, PVCA-bas, PVCA-ap) were observed in all rats. RESULTS: Despite preserved systolic function (FS, LVEF), the HT-NLVH and HT-LVH groups exhibited diastolic impairment (elevated LAVI, E/e') (all p&#x2009;<&#x2009;0.05). LS-ap declined only in HT-LVH, while LS-mid and LS-bas worsened from HT-NLVH to HT-LVH, and the HT-LVH group exhibited a significantly elevated P-ap (all p&#x2009;<&#x2009;0.05). P-ap was associated with LV remodeling indexes and E/e' (all p&#x2009;<&#x2009;0.05). Compared with WKY, LS-bas decreased in SHR (p&#x2009;<&#x2009;0.05). The SHR group demonstrated significantly elevated PVCA-bas, PVCA-ap, and CVF-bas (p&#x2009;<&#x2009;0.05), while the CVF-ap had no significant difference. CONCLUSION: Myocardial dysfunction and fibrosis exhibited regional heterogeneity with predominant basal damage and apical sparing in hypertensive cardiac hypertrophy. This apical-sparing pattern correlated significantly with both diastolic dysfunction and hypertrophic progression, suggesting its potential as a clinically observable hallmark.