Decrease in Coronary Flow After Consecutive Injections of Contrast Media During Coronary Angiography

Background. TIMI frame count (TIMIfc) is widely used to assess coronary flow during angiography and there are studies showing the effects of contrast media on blood cells. In this study, we investigate changes in coronary flow and in red blood cells following contrast injections. Methods and Results. Coronary flow was assessed by TIMIfc in the left anterior descending and circumflex coronary arteries of patients undergoing elective angiography. Changes in the morphology of red blood cells and in the mean corpuscular volume (MCV) were evaluated by optical microscopy. We enrolled 24 patients with a mean age of 61.9 +/- 12 years. In 45 coronary arteries, the mean baseline-corrected TIMIfc was 19.4 +/- 3.46 frames and the final one was 24.3 +/- 3.2 frames (P=.001) with a mean increase of 4.92 +/- 0.25 frames (frame range, 0-10), indicating significant impairment of coronary flow. There was an increase in the number of crenated red cells per camp (4.3 +/- 3.4%; P=.001). The MCV changed from 86.6 +/- 4.7 fL to 86.8 +/- 4.6 fL (P=.011). There was no association of the TIMIfc increase with changes in either crenated red cells (P=NS) or MCV (P=NS). Conclusion. There was significant impairment of coronary artery flow following contrast injections during angiography. These findings indicate that the TIMIfc is affected by the timing of assessment during angiography, with implications for clinical trial design and for the use of TIMIfc as a surrogate endpoint. In addition, this impairment of coronary flow may have implications for slow flow observed during coronary interventions.