Comparison of myocardial perfusion reserve before and after coronary balloon predilatation and after stent implantation in patients with postangioplasty restenosis

Background Stents provide a scaffold for coronary arteries after angioplasty a Methods and Results In 25 patients with postangioplasty restenosis of the left anterior descending artery, ECG-gated digital subtraction coronary angiograms were recorded at baseline and during hyperemia (12 mg papaverine IC) before and after balloon predilatation (PTCA), after implantation of a Palmaz-Schatz stent, and after 6 months. Densitometric evaluation revealed different time and density parameters to calculate two definitions of myocardial perfusion reserve (MPRI and MPR2) and maximum flow ratio (MaxFR). Poststenotic MPRI increased from 1.57+/-0.14 to 2.59+/-0.86 after PTCA and to 3.10+/-0.41 after stenting, with 2.90+/-0.65 at follow-up (ANOVA, P<.05), while reference MPR1 remained unchanged at 3.10+/-0.40. Poststenotic MPR2 increased from 1.36+/-0.28 to 2.50+/-1.20 and to 3.40+/-0.58, respectively, with 3.20+/-0.92 at follow-up (ANOVA, P<.05), while reference MPR2 remained unchanged at 3.40+/-0.60. MaxFR was 2.13+/-0.53 after PTCA, elasticity 2.83+/-0.35 after stenting, and 2.73+/-0.58 at follow-up (ANOVA. P<.05). A good correlation was found between minimal stenotic luminal diameter and MPR1 or MPR2 (r=.87 and r=.94) and between luminal gain and MaxFR (r=.75). A negative correlation was measured between recoil and MPR1, MPR2, and MaxFR (r=-.80, r=-.86, and r=-.83). At follow-up, a steeper correlation was found between MPR and minimal stenosis diameter (MPRI: slope, 0.52 versus 0.91: MPR2: slope, 1.48 versus 1.95) and between MaxFR and net limen gain (slope, 0.78 versus 1.27). Conclusions Coronary stent implantation in patients with postangioplasty restenosis normalized poststenotic myocardial perfusion immediately as a result of a larger postprocedural lumen and a more pronounced inhibition of elastic recoil. After 6 months this benefit was sustained despite progressive lumen loss.