Lack of correlation between angiographic grading of collateral and myocardial perfusion and function: implications for the assessment of angiogenic response

Background Angiographic assessment of apparent collaterals (AAC) has been used to quantify the angiogenic response to interventions designed to enhance myocardial perfusion and function in ischemic myocardium. However, the accuracy with which AAC reflects actual myocardial blood flow (MBF) and regional contractility has not been established. Objective To examine the relationships between myocardial tissue perfusion, AAC grade and myocardial function in a porcine model of chronic myocardial ischemia. Methods AAC (with results visually graded as 0-3) was performed 4 weeks after placement of an ameroid constrictor around the left circumflex artery in pigs (n= 27), Fluorescent microspheres were used to quantify regional endocardial, epicardial, and transmural MBF, and echocardiography was used to assess percentage thickening of myocardium (PTM) at rest and under stress (pacing). Results There was no significant correlation between AAC grading and endocardial, epicardial or transmural MBF, MBF but not AAC grade was correlated to PTM at rest according to the formula PTM = 0.06 + 0.42MBF(transmural) (r= 0,39, P= 0.047). Conclusion Results of simple AAC are not correlated with myocardial perfusion and function and probably should not be used as a primary endpoint in clinical studies designed to enhance myocardial perfusion in ischemic regions. Coron Artery Dis 12:173-178 (C) 2001 Lippincott Williams & Wilkins.