Primary coronary microvascular dysfunction and poor coronary collaterals predict post-percutaneous coronary intervention cardiac necrosis

Background An elevation in cardiac troponin-I (cTnI) after elective percutaneous coronary intervention (PCI) is because of cardiac necrosis and has prognostic implications. Primary microvascular dysfunction, evident before PCI, and paucity of coronary collaterals at baseline may influence cTnI. Methods We selected 22 patients awaiting elective PCI for a single-vessel, type-A coronary stenosis, with normal left ventricular function and a normal preprocedure cTnI. Intracoronary pressure and Doppler flow were measured during coronary balloon occlusion to derive microvascular resistance: R-p=[P-d(occl)-P-v]/APV(occl), and collateral resistance: R-coll=[P-a-P-d(occl)]/APV(occl), at each stage of PCI, where P-a is mean aortic pressure, P-v is central venous pressure, P-d(occl) is mean distal pressure, R-p is coronary microvascular resistance, R-coll is coronary collateral resistance, and APVoccl is average peak velocity during coronary balloon occlusion. The resistance indices were compared with postprocedural cTnI levels measured at 24h. Results There was a relationship between baseline R-p before PCI and elevated plasma cTnI levels at 24 h. Mean (SEM) R-p (mmHg/cm/s) increased for each cTnI tertile: T1 (mean cTnI 0.04 ng/ml): 1.3 (0.3), T2 (mean cTnI 0.13 ng/ml): 3.1 (0.4), and T3 (mean cTnI 2.5 ng/ml): 4.6 (0.7) (P=0.002). Baseline R-coll (mmHg/cm/s) was similarly related to cTnI result and mean values showed an increasing trend: T1: 11.1 (1.9), T2: 14.5 (2.3), and T3: 19.5 (3.4) (P=0.12). Serial coronary balloon occlusions did not significantly alter R-p (P=0.82) or recruit coronary collaterals (P=0.69). Conclusion Primary coronary microvascular dysfunction and poor collaterals at baseline are associated with post-PCI necrosis. Coron Artery Dis 20:253-259 (C) 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins.