Novel Advanced Echocardiographic Evaluation of the Left Atrium: Stroke and Hypertrophic Cardiomyopathies

Abstract

Background

Left atrial (LA) myopathy contributes to atrial fibrillation (AF) and thromboembolism. Many strokes are cryptogenic, aka embolic stroke with undetermined source (ESUS). Moreover, hypertrophic cardiomyopathies often exhibit LA myopathy, and thus increased risk of AF/stroke. Aim: to examine novel echocardiographic parameters of LA myopathy in these conditions.

Methods and Results

Multiple methodologies were utilised including prospective and retrospective observational studies. Part 1 explores the LA myopathy in stroke and thromboembolism. Abnormal LA volume, function (incl. strain) and spherical shape are demonstrated on a spectrum, with controls and AF/cardioembolic stroke at both ends, with ESUS lying in the middle. The novel parameter of increased LA sphericity was found to be an early feature of LA myopathy, present in a significant proportion of ESUS patients.

Part 2 explores LA myopathy in hypertrophic cardiomyopathies. Echocardiographic ratios could differentiate cardiac amyloidosis, Anderson-Fabry cardiomyopathy and hypertensive heart disease. Patients with ATTR (transthyretin) demonstrated greater LA myopathy compared to AL (light chain) cardiac amyloidosis, with increased LA size, reduced strain, and higher left atrial mechanical dispersion (LA-MD), a novel marker of interatrial dyssynchrony. Finally, LA minimum volume predicted mortality in AL.

Part 3 explores specific barriers to the utility of LA echocardiographic parameters. Inter-vendor variability of LA strain is demonstrated, and a solution with a calibrated measurement is proposed. Finally, LA volume indexation across different races is explored, and allometric height indexation was found to be superior than body surface area indexation.

Conclusions

LA myopathy has significant clinical and prognostic significance. This thesis supports utility of echocardiographic LA parameters in the assessment of LA myopathy in the two major clinical entities of stroke and hypertrophic cardiomyopathies.