NORMALIZATION OF MYOCARDIAL PERFUSION RES ERVE AFTER CORONARY STENT IMPLANTATION IN CONTRAST TO BALLOON ANGIOPLASTY

Stents scaffold coronary arteries after angioplastic treatment and inh ibit elastic recoil resulting in a larger and more circular focal lume n. In 25 patients with significant stenoses of the left anterior desce nding coronary artery, presenting no collaterals or myocardial infarct ion, EKG-gated digital subtraction angiograms were recorded at baselin e and during hyperemia induced by intracoronary injection of 12 mg pap averine before and after balloon angioplasty, and after adjunct implan tation of a single Palmaz-Schatz stent. Densitometric evaluation revea led the time parameters contrast medium appearance time (MCAT), rise t ime (RT) and mean transit time (MTT) and maximum intensity (Imax). Myo cardial perfusion reserve (MPR1) was calculated as the ratio of baseli ne MCAT and hyperemic MCAT multiplied by the ratio of hyperemic Imax a nd baseline Imax while MPR2 was calculated as the ratio of baseline RT and hyperemic RT. Maximum flow ratio (MaxFR) was calculated as the ra tio of preprocedural hyperemic MTT and postprocedural hyperemic MTT. P oststenotic MPR1 increased from 1.36 +/- 0.28 to 2.50 +/- 1.20 and to 3.40 +/- 0.58 (ANOVA p < 0.05), while reference MPR1 remained unchange d with 3.40 +/- 0.60. Post-stenotic MPR2 increased from 1.57 +/- 0.14 to 2.59 +/- 0.86 after balloon angioplasty and to 3.10 +/- 0.41 after stenting (ANOVA p < 0.05), while reference MPR2 remained unchanged wit h 3.10 +/- 0.40. MaxFR was 2.13 +/- 0,53 after balloon angioplasty and 2.83 +/- 0.35 after stenting (p < 0.05). A good correlation was found between minimal stenosis diameter and MPR1 or MPR2 (MPR1: r = 0.94; M PR2: r = 0.87) and between luminal gain and MaxFR (r = 0.75). A negati ve correlation was measured between recoil, defined as the difference between inflated balloon diameter and resulting minimal stenosis diame ter, and MPR1 and MPR2 and MaxFR (MPR1: r = -0.86; MPR2 r = -0.80; Max FR r = -0.83). In conclusion, adjunct coronary stent implantation norm alized poststenotic myocardial perfusion immediately in contrast to ba lloon angioplasty alone resulting from a larger postprocedural lumen a nd a more pronounced inhibition of elastic recoil.