Objectives: Post systolic shortening (PSS) had been shown to be sensitive in detecting ischemia on stress echocardiography. This work aims to study the diagnostic potential of resting PSS and post systolic index (PSI) in patients with suspected unstable angina (UA).
Methods: Total of 159 participants with suspected UA without any wall motion abnormalities were recruited. They all underwent speckle tracking echocardiography (STE) and coronary angiogram (CAG). Global longitudinal strain (GLS), presence or absence of pathological PSS, PSI17 and PSI12, PSI in left anterior descending, left circumflex and right coronary artery territories were assessed. Based on CAG those who had more than 70% stenosis were labelled to have obstructive CAD.
Results: Obstructive disease was noted in 54.7% patients. The prevalence of PSS (62.1% Vs 13.9%), mean PSI17 (5.4 Vs 3.3) and PSI12 (6.2 Vs 3.7) were significantly higher in those with CAD compared to patients without obstructive disease. Both PSS (Odds ratio-10.145; 95% CI, 4.577-22.489; p=0.001) and PSI17 (odds ratio-1.217;95 CI, 1.064-1.393; p=0.004) were predictors of CAD by multivariate regression analysis. PSS had a sensitivity of 62.1% and specificity of 86.1% with a positive predictive value of 84.4%. PSI17 (area under curve- 0.637; p=0.003) and PSI12 (AUC- 0.661; p=0.001) have moderate accuracy in identifying obstructive CAD.
Conclusion: In patients presenting with suspected UA, STE derived PSS has reasonable sensitivity and good specificity in diagnosis of obstructive CAD. Patients identified to have PSS can be subjected to CAG without further stress testing because of its high positive predictive value.