Longitudinal myocardial function is more compromised in cardiac syndrome X compared to insignificant CAD: Role of stress echocardiography and calcium scoring.

Abstract

The aim of this study was to assess the nature of myocardial dysfunction in the cardiac syndrome X (CSX) and insignificant coronary artery disease (ICAD) using dobutamine stress echocardiography (DSE) and coronary calcium scoring (CAC). We prospectively studied 35 consecutive patients who complained of exertional angina, had ≥1mm ST shift on exercise stress test but normal or no obstructive CAD (<50%) on angiography. Patients were divided into CSX (n=27) with normal arteries and ICAD (n=8) with insignificant stenosis. CSX patients had more females, lower calcium score and less prevalent cardiac risk factors compared to ICAD (p<0.05 for all). At peak stress, MAPSE and TAPSE failed to increase in both groups. LV septal and lateral s' increased in the two groups but the increment increase was less in CSX than ICAD (p<0.05) while other diastolic indices did not differ between groups (p>0.05 for all). CAC correlated modestly with LV and RV systolic velocities: septal s' (r=-0.65, p<0.001) lateral s' (r=-0.35, p=0.04) and right s' (r=-0.53, p=0.005) in CSX, while in ICAD patients only with RV s' (r=-0.58, p=0.02). On multivariate model, only septal s' OR 1.816 (1.1090-3.820, p=0.04) proved the most powerful independent predictor of CAC. Compromised LV longitudinal systolic velocities were more pronounced and calcium score as a surrogate for atherosclerosis was lower in CSX than ICAD. These findings strengthen the evidence for different pathogenesis of CSX compared to ICAD, with microvascular disease in the former and calcification in the latter.