High microvascular resistance and reduced left atrial strain in patients with coronary microvascular dysfunction: The micro-strain study

Background: It is already known that high coronary microvascular resistance (R mu) is linked to altered left ventricular stiffness and might be an early indicator of heart failure with preserved ejection fraction (HFpEF). Left atrial dysfunction, on the other hand, varies according to the grade of left ventricular diastolic dysfunction. This is the first study to use the latest development for invasive assessment of R mu and to combine it with echocardiographic assessment of left atrial strain during reservoir phase (LASr) by speckle tracking in relation to left ventricular (LV) diastolic function. Methods and results: An invasive angiogram was performed in 97 patients because of suspected ANOCA. All patients underwent comprehensive echocardiography, yet image quality was poor in 15 patients leaving 82 patients to include in the final analysis. In order to compare R mu with LASr values, patients were divided into 4 groups based upon normal values of R mu as defined by Fournier et al. The mean LASr was plotted against the four resistance groups. The LASr was 48.6% in the lowest resistance group, and 40.1%, 36.3% and 30.1% in the low intermediate, high intermediate and high resistance group respectively. These differences were significant compared to the lowest resistance group (p < 0.05). Although higher R mu groups showed more diastolic dysfunction, LASr was already decreased irrespective of the severity of diastolic dysfunction. Conclusion: This study shows a relationship between increased R mu and reduced LASr, that seems to precede conventional measures of left ventricular diastolic dysfunction. This suggests that microvascular dysfunction might be an early indicator for the development of impaired LA function. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study demonstrates a correlation between increased R mu and reduced LASr, which appears to occur prior to conventional left ventricular diastolic dysfunction measures. Microvascular dysfunction may serve as an early indicator for the development of impaired LA function.