Assessment of collateralized myocardium with Cardiac Magnetic Resonance (CMR): Transmural extent of infarction but not angiographic collateral vessel filling determines regional function and perfusion in collateral-dependent myocardium

BackgroundAngiographic collateral vessel filling is limited to evaluate collateral-dependent myocardium. We hypothesize, that quantitative assessment of regional myocardial function, perfusion and viability with Cardiac Magnetic Resonance (CMR) adds complementary information to angiography of collateralized myocardium.MethodsCMR was performed in 30 patients with one chronic occluded coronary artery and no further flow limiting stenosis to assess transmural extend of infarction (TEI), resting perfusion and perfusion during adenosine-induced hyperemia and regional wall thickening (RWT) in collateral-dependent and antegradely-perfused myocardium. Collateral vessels were evaluated by angiography and the Rentrop grade (0–3).ResultsIn 15 patients with < 50% TEI in collateral-dependent myocardium resting perfusion (1.08 ± 0.22 ml/min/g), hyperemia (2.21 ± 0.73 ml/min/g) and RWT (4.0 ± 2.6 mm) were similar to antegradely-perfused myocardium (rest 1.14 ± 0.20 and hyperemia 2.46 ± 0.82 ml/min/g, RWT 4.3 ± 1.7 mm). In 15 patients with ≥ 50% TEI in collateral-dependent myocardium resting perfusion and hyperemia as well as RWT were significantly lower (rest 0.84 ± 0.19, p < 0.001 and hyperemia 1.34 ± 0.43 ml/min/g, p < 0.001; RWT 1.0 ± 1.0 mm, p < 0.0001) compared to antegradely-perfused myocardium. There was an inverse correlation between TEI and resting or hyperemic perfusion or RWT. In contrary, resting perfusion and hyperemia as well as RWT in collateral-dependent myocardium were not different between patients with good (2–3) compared to patients with poor Rentrop grade (0–1). There was no correlation between TEI and Rentrop grade.ConclusionFunction and perfusion in collateral-dependent myocardium are preserved, if transmural extent of infarction is limited (< 50%). This is independent of their angiographic collateral vessel filling. Thus, CMR adds complementary information to angiographic standard assessment of collateral vessels.