Immediate recruitment of dormant coronary collaterals can provide more than half of normal resting perfusion during coronary occlusion in patients with coronary artery disease

Aims Dormant coronary collaterals are highly prevalent and clinically beneficial in cases of coronary occlusion. However, the magnitude of myocardial perfusion provided by immediate coronary collateral recruitment during acute occlusion is unknown. The aim of this study was to quantify collateral myocardial perfusion during balloon occlusion in patients with coronary artery disease (CAD). Methods and results Patients without angiographically visible collaterals undergoing elective percutaneous transluminal coronary angioplasty (PTCA) to a single epicardial vessel underwent two scans with 99m Tc-sestamibi myocardial perfusion single-photon emission computed tomography (SPECT). All subjects underwent at least three minutes of angiographically verified complete balloon occlusion, at which time an intravenous injection of the radiotracer was administered, followed by SPECT imaging. A second radiotracer injection followed by SPECT imaging was performed 24 hours after PTCA. The study included 22 patients (median [interquartile range] age 68 [54-72] years, 10 (45%) female). The perfusion defect extent was 19 [11–38] % of the LV, and the collateral perfusion at rest was 64 [58-67]% of normal. Conclusion This is the first study to describe the magnitude of short-term changes in coronary microvascular collateral perfusion in patients with CAD. On average, despite coronary occlusion and an absence of angiographically visible collateral vessels, collaterals provided more than half of the normal perfusion. Graphical abstract Dormant collaterals are highly prevalent but the magnitude of myocardial perfusion provided by immediate coronary collateral recruitment during acute occlusion in humans is unknown. Patients without angiographically visible collaterals underwent intravenous injection with 99mTc-sestamibi during coronary balloon inflation followed by SPECT imaging. A control scan was performed 24 hours later..Median collateral perfusion during coronary occlusion was 64% of normal.