Characterisation of coronary microvascular dysfunction with left atrial and left ventricular strain assessed with 2D speckle-tracking echocardiography

Coronary microvascular dysfunction (CMD) is a complex entity involving functional and structural abnormalities in the coronary microcirculation. The impact of different CMD endotypes on myocardial remodelling assessed by strain imaging remains inadequately characterised.

Eighty patients underwent resting transthoracic echocardiography and invasive physiological assessment of coronary microvascular function. Functional and structural CMD were defined according to coronary flow reserve (CFR) and the index of microvascular resistance (IMR). Vasospastic angina (VSA) was diagnosed with an acetylcholine vasoreactivity test. Peak atrial longitudinal strain (PALS), left atrial conduit strain (LACS), and global longitudinal strain (GLS) of left ventricle were measured by speckle-tracking echocardiography.

Compared with patients without CMD, those with functional or structural CMD showed significant lower PALS (30.8±6.6 vs. 23.8±6.7 vs. 25.0±7.8, p<0.01); LACS (16.2±4.9 vs. 11.1±4.6 vs. 11.2±5.6, p<0.01) and GLS (18.3 ± 2.4 vs. 15.1 ± 3.0 vs. 15.0 ± 4.0, p<0.01), with a significant progressive decline across groups (p for trend <0.01). CFR directly correlated with PALS, LACS and GLS (r=0.3, p<0.01; r=0.4, p<0.01; r=0.3, p=0.02; respectively), while IMR showed inverse correlation (rho=-0.2, p=0.05; rho=-0.3, p=0.02; rho=-0.3, p=0.02; respectively). Compared with patients with No-CMD and VSA, those with endothelium-independent CMD had significantly lower PALS (30.2±6.6 vs. 28.9±7.4 vs. 24.9±7.7, p=0.02), LACS (16.3±4.8 vs. 14.2±6.2 vs. 11.2±5.3, p<0.01) and GLS (19.2±2.4 vs. 17.3±3.4 vs. 14.8±3.6, p<0.01) (p for trend <0.01).

Endothelium-independent CMD, mainly structural dysfunction, is associated with early functional atrial and ventricular impairment, with a progressive decline across different endotypes, suggesting a potential continuum within the spectrum of CMD.For image description, please refer to the figure legend and surrounding text.  For image description, please refer to the figure legend and surrounding text.