Physiologically assessed coronary collateral flow and adverse cardiac ischemic events: a follow-up study in 403 patients with coronary artery disease

Objectives We sought to evaluate whether coronary collateral flow is clinically relevant for future cardiac ischemic events. Background The link between good collateral supply related to less myocardial damage and fewer cardiac events has not been established prospectively beyond doubt. Methods In 403 patients with stable angina pectoris undergoing percutaneous transluminal coronary angioplasty (PTCA) and quantitative collateral assessment, the occurrence of major adverse cardiac events ([MACE] cardiac death, myocardial infarction, unstable angina pectoris) and stable angina pectoris was monitored during follow-up. Collateral flow index (CFI) was determined using intracoronary pressure or Doppler guidewires. Mean aortic ([Pao] mm Hg) and distal coronary artery occlusive pressure ([Poccl] mm Hg) during balloon angioplasty (PTCA), or distal coronary flow velocity time integral during ([Voccl] cm) and after ([Vø-occl] cm) PTCA were measured continuously. Pressure-derived CFI was calculated as follows: (Poccl − 5)/(Pao − 5). Doppler-derived CFI: Voccl/Vø-occl. Patients were subdivided into a group with well (CFI ≥ 0.25) and poorly developed collaterals (CFI < 0.25). Results Average follow-up was 94 ± 56 (15 to 202) weeks. There were 134 patients with CFI ≥0.25 (61 ± 11 years) and 269 with CFI <0.25 (61 ± 10 years). The overall cardiac ischemic event rate (MACE and stable angina pectoris) during follow-up was 23% in patients with CFI ≥0.25 and 20% in patients with CFI <0.25 (p = NS). However, only 2.2% of patients with good collateral flow suffered a major cardiac ischemic event, compared with 9.0% among patients with poorly developed collaterals (p = 0.01). The incidence of stable angina pectoris was significantly higher in patients with well developed collaterals than in those with poorly developed collaterals (21% vs. 12%; P = 0.01). Conclusions In this relatively large population with chronic stable coronary artery disease undergoing quantitative collateral measurement, the beneficial impact of well developed collateral vessels on the occurrence of future major cardiac ischemic events is clearly demonstrated.