How to predict myocardial injury in patients with large ischaemic burden identified during stress echocardiography?

Abstract Background/Introduction Stress echocardiography (SE) is well established diagnostic tool in coronary artery disease (CAD) with broadly agreed consensus for the indications and protocols. There is, however, no clear non-invasive SE parameter in identifying high risk features in patients with large burden of inducible regional wall motion abnormalities (RWMA) that would require prompt treatment or urgent admission. Purpose To identify high risk features during SE associated with myocardial injury following a positive SE with large amount of RWMA. Methods All consecutive patients referred for SE from June 2019 to November 2022 to diagnose coronary artery disease were assessed for inducible RWMAs using a hybrid protocol (low dose Dobutamine and exercise on supine bike with 3 min increments of workload of 25W). Those with ≥4/17 segments of inducible RWMAs underwent measurement of Troponin level 1 hour after the test termination. Somatometric characteristics, risks factors, symptoms, haemodynamic pre- and during SE and results of subsequent coronary angiography were recorded. Results 631 patients were referred for assessment of CAD. 87 patients had ≥4/17 inducible RWMAs out of 152 patients with positive SE. 61/87 who had Troponin measurements were included in the analysis. Mean age was 65 ± 13 yo, 61% were male. There was high prevalence of known CAD (77%) and cardiovascular risks factors as hypertension (59%) and hyperlipidaemia (61%). The median exercise time was 9 minutes, 46% developed chest pain (CP), 49% - ECG changes, 39% - left ventricular (LV) dilatation and 74% - reduction in LVEF. Troponin was positive in 25/61 patients. Invasive coronary angiography confirmed clinical CAD in 51/61 patients. 5 patients had either normal angiogram or non-obstructive CAD, 5 patients were awaiting diagnostic test. The severity of CAD appears to be associated with magnitude of Troponin release (1 vessel disease - 16.5 ng/L, 2 vessels disease - 39.9 ng/L, 3 vessels disease – 58.2 ng/L). All patients (6/61) with higher troponin values (>90ng/L) had multivessel disease involving the left anterior descending (LAD) artery. Interestingly, 2/5 patients without CAD had elevated Troponin suggesting possible ongoing myopathic process. The only non-invasive SE parameters that were significantly related to troponin increase were recovery time (P=0.001) and exercise time (P<0.05) whereas symptoms, BP response and LVEF reduction showed a trend which did not achieve significance. Conclusions In patient with positive SE with large burden of inducible RWMAs prolonged recovery time and low threshold for ischaemia appear to be the most reliable characteristic to identify patients with potential myocardial injury and should be used as a triaging tool for admission or early invasive assessment.