Diagnostic value of dobutamine stress Doppler tissue imaging in diabetic patients with suspected coronary artery disease

Coronary artery disease (CAD) is often silent in diabetic patients, and it is typically in advanced stages of development by the time it manifests. Various forms of stress testing have been investigated to detect obstructive CAD in diabetes mellitus. To assess the diagnostic value of dobutamine stress pulsed-wave Doppler tissue imaging (DTI) compared with standard wall motion analysis in detection of myocardial ischemia in diabetic patients with suspected CAD. The study comprised 46 diabetic patients with suspected CAD who underwent dobutamine stress echocardiography (DSE) with DTI within 4 weeks before coronary angiography (CA). Dobutamine infusion started at 5 μ/kg/min and increased up to 40 μ/kg/min with additional atropine during submaximal heart rate responses. In addition to wall-motion score index (WMSI) analysis, pulsed-wave DTI examination of basal and mid segments of posteroseptal, lateral, anterior, inferior and anteroseptal walls was performed. Myocardial velocities were measured at rest in the apical 4, 3 and 2-chamber views. The measurements were repeated at low dose (10–15 μ/kg/min) and at peak stress (40 μ/kg/min). DTI measurements included peak systolic velocity (S), peak early diastolic velocity (E) and peak late diastolic velocity (A) and the results were compared to WMSI analysis. Patients were classified into two groups according to CA results; group (I) diabetics with positive CA (n = 27) and group (II) diabetics with negative CA (n = 19). There was no significant difference between the two groups in duration of diabetes, global WMSI at rest or the Δ changes (stress-rest/rest) of WMSI (p > .05). Global S and global E were significantly lower in group I compared to group II at peak stress (11.3 ± 3.7 cm/s vs. 14.5 ± 2.2 cm/s, p < 0.01) and (11.3 ± 1.6 cm/s vs. 13.1 ± 2.1 cm/s, p < 0.01) respectively. The cutoff points for global S and global E to detect obstructive CAD in diabetics were 11.3 cm/s and 11.2 cm/s respectively with 75.7%, 73.4% sensitivity and 94.7%, 89.47% specificity respectively. An increment (Δ changes) less than 0.56 in S or 0.26 in E from rest to peak stress identified CAD with 78.8%, 89.3% sensitivity and 94.7%, 90.7% specificity respectively. The accuracy of DTI parameters during peak stress was higher than WMSI analysis (sensitivity 74.1% vs. 59.3% and specificity 90% vs. 79%, p < 0.01 for each). In multivariate regression analysis, only ΔS and ΔE were independent predictors of obstructive CAD in diabetics (odd ratio: 36.16, 95% CI, 1.34–532.01 and 63.77, 95% CI, 3.19–721.47) respectively. Quantitative analysis, using DTI during DSE, adds new dimension in diagnosis of myocardial ischemia. It is more sensitive, specific, accurate and reproducible compared with standard wall motion analysis for recognition of significant CAD in diabetic patients.