Six simultaneously employed methods to gauge the coronary collateral flow of the decade

A 59-year-old woman with bronchial asthmaand obesity underwent coronary angiographybecause of exertional dyspnea and atypicalchest pain both at rest and sometimes duringexertion. Coronary angiography revealed achronic total occlusion (CTO) of the proximalleft anterior descending (LAD) artery (fig. 1A).Systolic left ventricular (LV) function was nor-mal (fig. 1B, 1C). Angiography of the right coro-nary artery showed a large collateral artery tothe LAD and some smaller septal collateralvessels (fig. 2A). The very well developed coro-nary collateral circulation protected the pa-tient entirely from a large anterior myocardialinfarction. Moreover, it was likely sufficient toprevent angina pectoris even under physicalexertion. There are more than half a dozenmethods for collateral assessment, six of themperformed in this particular patient. The pres-ence of normal LV anterior wall motion in thepresence of a CTO of the LAD qualifies collat-erals as relevant enough to prevent myocar-dial infarction (fig. 1B, 1C). The coronary an-giographic assessment, first described by Ren-trop et al., qualifies naturally or artificially(fig. 2B) occluded coronary arteries accordingto the degree (0–3) of retrograde filling by col-lateral vessels (grade 3 as in the present casewith entire filling of the balloon-occluded LAD)[1]. Two further methods for the characterisa-tion of well developed collaterals during a briefcoronary balloon occlusion are the absence ofST-segment changes in the intracoronary ECG(fig. 3), and the lack of angina pectoris. Meas-urement of invasively derived collateral flowindex (CFI) or contrast-echocardiography-ob-tained collateral perfusion index (CPI) provide