Abstract 19457: Collateral Blood Supply is Associated with Smaller Infarct Size, but less Ischemia, a Myocardial Perfusion Stress Cardiovascular Magnetic Resonance Study
Introduction: Cardiovascular magnetic resonance (CMR) allows the identification and quantification of ischemia, infarction size and myocardial viability. Coronary chronic total occlusions (CTOs) are commonly encountered complex lesions identified in up to 30% of all patients referred for coronary angiography. The physiological consequences of CTOs are incompletely understood. Single photon emission computed tomography has been used to investigate this, however, low spatial resolution is a compromising factor in these studies.
Methods and Results: Fifty-two consecutive patients with a CTO scheduled for PCI underwent dipyridamole first-pass myocardial perfusion stress CMR. All patients underwent angiography with 90 days (mean 19) of stress testing. Collateral circulation was noted to be good (Rentrop grade 2, 3) in thirty-eight patients and poor (Rentrop grade 0, 1) in fourteen. All patients had abnormal stress perfusion. Forty-two patients had detectable myocardial infarction; twenty-five of these were known to have infarction by history or ECG findings. Patients with poor collateral blood supply had larger infarction size (2.4 vs 1.2 segments, p=0.02) and more non-viable segments (0.43 vs 0.11, p=0.03). Good collateral blood supply did not prevent detectable ischemia (3.6 vs 4.3 segments, p=0.31).
Conclusion: CMR of patients with chronic total occlusions detects many more infarcts than history or ECG alone (80% vs 42%). Good collateral blood supply is associated with a smaller infarct size. However, Rentrop grade 2 or 3 blood supply does not imply adequate blood supply. Patients with CTOs should undergo stress testing, preferably with CMR, to identify viability and ischemia. This can select those that would benefit most from revascularization.
- © 2010 by American Heart Association, Inc.