Left ventricular extracellular volume fraction and atrioventricular interaction in hypertension

Objectives Left atrial enlargement (LAE) predicts cardiovascular morbidity and mortality. Impaired LA function also confers poor prognosis. This study aimed to determine whether left ventricular (LV) interstitial fibrosis is associated with LAE and LA impairment in systemic hypertension. Methods Following informed written consent, a prospective observational study of 86 hypertensive patients (49±15 years, 53% male, office SBP 168±30mmHg, office DBP 97± 4 mmHg) and 20 normotensive controls (48±13 years, 55% male, office SBP 130±13 mmHg, office DBP 80±11 mmHg) at 1.5T cardiovascular magnetic resonance was conducted. Extracellular volume fraction (ECV) was calculated by T1 mapping. LA volume (LAV) was measured with biplane area-length method. LA reservoir, conduit and pump function were calculated with the phasic volumetric method. Results Indexed LAV correlated with indexed LV mass (R=0.376, p<0.0001) and ECV (R=0.359, p=0.001). However, ECV was the strongest significant predictor of LAE in multivariate regression analysis (odds ratio [95th confidence interval]: 1.24 [1.04–1.48], p=0.017). Indexed myocardial interstitial volume was associated with significant reductions in LA reservoir (R=-0.437, p<0.0001) and conduit (R=-0.316, p=0.003) but not pump (R=-0.167, p=0.125) function. Multiple linear regression, correcting for age, gender, BMI, BP and diabetes, showed an independent decrease of 3.5% LA total emptying fraction for each 10ml/m2 increase in myocardial interstitial volume (standard β coefficient: -3.54, p=0.002). Conclusions LV extracellular expansion is associated with LAE and impaired LA reservoir and conduit function. Future studies should identify if targeting diffuse LV fibrosis is beneficial in reverse remodeling of LA structural and functional pathological abnormalities in hypertension.