Myocardial function reclassification: Echocardiographic strain patterns in patients with chronic Chagas cardiomyopathy and intraventricular dyssynchrony

Background: We aimed to identify, among Chronic Chagas Cardiomyopathy (CCC) patients with left ventricular dysfunction (LVD) and non-left bundle branch block (non-LBBB), subgroups with different functional and mechanical patterns of global longitudinal strain (GLS) and intraventricular dyssynchrony (IVD) at rest and after exercise stress test, and reclassify them using a new echocardiographic approach. Methodology: In this single-center cross-sectional study, 40 patients with CCC, left ventricular ejection fraction (LVEF) ≤ 35% and non-LBBB underwent rest echocardiography and then treadmill exercise stress echocardiography with GLS and IVD analysis. The sample was divided into four groups, based on GLS and IVD significant variation between rest and exercise: GLS + IVD+ (9 patients); GLS + IVD- (9 patients); GLS-IVD+ (10 patients); GLS-IVD- (10 patients). Results: At rest, median LVEF was 28% (21.3%–33%) and GLS (−7% (−5%/−9.3%), were not different among groups. The average response of GLS was an increase of 0.74% over rest values, and the average response of IVD was a decrease of 6.9 ms. Group GLS-IVD+ presented more dyssynchrony at rest (p = 0.01). Left atrial (LA) volume (higher in GLS-IVD-) (p = 0.022) and TAPSE (higher in GLS + IVD+) (p = 0.015) were also different among groups at baseline. Of the 40 patients evaluated, 27 (67.5%) had very severe LVD (GLS < −8%). In addition, among these patients, 11 patients had contractile reserve after undergoing stress echocardiography. Conclusions: In patients with CCC, severe LVD and non-LBBB, the evaluation of GLS and IVD between rest and exercise was able to reclassify myocardial function and to identify subgroups with contractile reserve and significant dyssynchronopathy.