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RESEARCH PRODUCT

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

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Background Stents provide a scaffold for coronary arteries after angioplasty and inhibit elastic recoil. 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 (MPR1 and MPR2) and maximum flow ratio (MaxFR). Poststenotic MPR1 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, 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 (MPR1: slope, 0.52 versus 0.91; MPR2: slope, 1.48 versus 1.95) and between MaxFR and net lumen 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.