Chronic total coronary occlusion in patients with intermediate viability: value of low-dose dobutamine and contrast-enhanced 3-T MRI in predicting functional recovery in patients undergoing percutaneous revascularisation with drug-eluting stent

Myocardial viability was evaluated by magnetic resonance imaging (MRI) in patients with chronic total coronary occlusion (CTO) treated with a drug-eluting stent. Change in left ventricular ejection fraction (LVEF) was analysed. Twenty-three patients with CTO underwent delayed-enhancement (DE) and low-dose dobutamine MRI (LD). Diastolic wall thickness (DWT), dobutamine-induced systolic wall thickening (SWT) and DE transmural extension were quantitatively assessed in vessel-related segments, calculating the contribution of viable tissue to SWT, expressed as viability index (VI)=[SWTx(100 - DE)]/100. Patients with transmural enhancement were excluded from revascularisation. At 6 months follow-up, patients underwent coronary angiography (CA) and MRI. Functional recovery was defined as a 2-mm increase in SWT. Transmural enhancement (mean DE 62.88 +/- 37.18] was present in three patients. Mean DWT, SWT, VI and DE of recanalised patients were 8.03 +/- 2.35, 2.64 +/- 1.56, 1.77 +/- 1.48 mm and 41.97 +/- 30.32. Revascularisation was successful in 14/16. Follow-up CA showed patency of treated vessels. Functional recovery was achieved in 13 patients. Functional recovery showed significant correlation with SWT (beta 1,779, p=0.015), and even higher correlation with VI (beta 2.032, p=0.011). LVEF improved significantly [Delta 95% confidence interval (CI) -4.47, p=0.0203). Invasive CTO treatment has beneficial effects on myocardial contractility that can be predicted by VI, and on LVEF.