Impact of catheter sizes and intracoronary glyceryl trinitrate on the TIMI frame count when digital angiograms are acquired at lower frame rates during elective angiography and PCI.

Unlabelled: The TIMI frame count (TFC) is a useful measure of coronary flow. To be widely applicable, the effect of different catheter sizes and the use of intracoronary glyceryl trinitrate (ICGTN) must be determined when films are acquired at lower acquisition rates (12.5 frames/s, f/s).

Methods: We compared 6F versus 5F diagnostic catheters (n = 44), 6F versus 7F diagnostic catheters (n = 45) and 6F diagnostic versus 7F guide catheters (n = 44). In the nitrate angiography group (n = 141), coronary angiography was performed before and after 200 micrograms of ICGTN. In the nitrate percutaneous coronary intervention (PCI) group (n = 48), coronary angiography was performed before and after 200 micrograms of ICGTN after the completion of the elective PCI procedure.

Results: The mean difference in the uncorrected TFC using 6F and 5F was 0.02 (95 % CI -0.5, 0.6; P = 0.9); using 6F and 7F diagnostic catheters it was 0.3 (95% CI -0.49, 1.1; p = 0.4); and using 6F diagnostic and 7F guide catheters it was 0.4 (95% CI -2.6, 3.4; P = 0.7) respectively. In the nitrate angiography group, the uncorrected TFC before and after ICGTN was 13.1+/-6.2 and 15+/-7.5 (equivalent to 31.4+/-14.9 and 36+/-2 at 30 f/s), with a mean difference of 1.9 (95% CI 1.3, 2.5; P = or <0.0001). In the nitrate PCI group, the uncorrected TFC before and after ICGTN administration was 9.2+/-3.7 and 10.3+/-4.2 (equivalent to 22.6+/-9.6 and 25.2+/-11 at 30 f/s) respectively with a mean difference between the two injections of 1.2 (95% CI -0.4, 1.9; P = 0.003).

Conclusion: We have demonstrated that the catheter sizes did not significantly affect the TFC when angiography was performed at 12.5f/s. The use of ICGTN significantly increased the TFC in both normal and diseased coronary arteries. This effect was also observed when ICGTN was administered into the culprit vessels after the completion of the elective PCI procedure. This effect must be considered when investigating the impact of specific treatments or drugs on coronary flow.