Modifications of Minimal Luminal Diameter During the 24 Hours Following Percutaneous Treatment of In-Stent Restenosis

Luminal renarrowing after percutaneous coronary interventions (PCI) typically occurs several weeks after the procedure. The time course for modification of the luminal geometry after dilatation of in-stent restenosis (ISR) has been less characterized. According to an intravascular ultrasound study,1 a significant renarrowing after redilatation of ISRs could be detected as early as 42 minutes after the procedure. However, no angiographic data are available on the modifications of luminal dimensions 24 hours after dilatation of an ISR. The aim of this study was to assess the quantitative angiographic parameters 24 hours after percutaneous treatment of ISR and to evaluate the relationship between changes in the minimal luminal diameter (MLD) and several angiographic and procedural characteristics. Materials and Methods Patients. All patients undergoing percutaneous treatment for symptomatic or silent myocardial ischemia attributable to an ISR were considered for enrollment in this single-center, prospective study. The exclusion criteria were an acute myocardial infarction within 30 days, restenotic lesions extending beyond the stent margins, implantation of additional stents during the procedure and inability to perform the angiographic examination at 24 hours. During the study period, 68 in-stent restenoses in 64 patients were treated. According to the exclusion criteria, 36 patients could not be considered. Therefore, the study was based on the remaining 30 ISRs in 28 patients. The study protocol was approved by the institutional review board and written informed consent was obtained from eligible patients. Procedural protocol. The procedure was performed via the femoral approach using a 6 to 8 French guiding catheter. All patients were on aspirin (100–180 mg/day) and received heparin to maintain the activated clotting time > 250 sec. The restenotic lesion was treated with balloon angioplasty (BA) or rotational atherectomy followed by balloon angioplasty (RA) according to the operator’s choice. RA was performed using the Rotablator system (Boston Scientific Corporation, Natick, Massachusetts). In the study patients, neither cutting balloon angioplasty nor directional coronary atherectomy were used. After the procedure, the femoral artery sheath was left in place and heparin infusion was started 6 hours post-procedure. The heparin infusion was titrated to maintain the partial thromboplastin time two to three times the upper normal limit. A control angiographic examination was performed 20 to 26 hours after the procedure. Angiographic analysis. Angiography was performed in two orthogonal projections after intracoronary injection of 0.2 mg of nitroglycerin. An end-diastolic frame in the projection that best showed the lesion severity was selected. The quantitative analysis was performed by a validated2 edge-detection algorithm (Intelligent Images QCA, Genoa, Italy). The untapered section of the tip of the catheter was used for calibration. The MLD and the interpolated reference diameter (RD), the latter defined as computer calculated estimation of the original coronary dimension at the site of the obstruction, were assessed. In case of a total occlusion in the pre-intervention angiogram, the MLD was assumed to be 0 and the diameter of the vessel proximal to the occlusion was substituted for the RD. The following indexes were derived from MLD and RD. Diameter stenosis was defined as 1 minus (MLD divided by RD). Gain was defined as post-intervention MLD minus baseline MLD, and early loss was defined as post-intervention MLD minus MLD at 24 hours. Statistical analysis. Categorical variables are expressed as absolute numbers and percents. Continuous variables are expressed as mean ± SD. The differences between lesions treated with BA or RA were assessed with a two-tailed, unpaired Student’s t test. MLD before, immediately, and 24 hours after the procedure were compared using ANOVA for repeated measurements. Linear regression analysis was used to calculate correlation coefficients between loss and the other angiographic parameters. P values Limitations. The major limitations of this study are the small sample size, the non-randomized allocation to BA or RA and the absence of an intravascular ultrasound examination. However, quantitative angiography is a generally accepted method to assess MLD and its serial modifications. Conclusions We conclude that early loss after successful redilatation of ISR is moderate, does not appear to be higher than that observed after BA of de novo lesions, and does not generally constitute a clinical problem.

1. Shiran A, Mintz GS, Waksman R, et al. Early lumen loss after treatment of in-stent restenosis: an intravascular ultrasound study. Circulation 1998;98:200–203. 2. Tommasini G, Rubartelli P, Piaggio M. A deterministic approach to automated stenosis quantification. Cathet Cardiovasc Intervent 1999;48:435–445. 3. Mintz GS, Popma JJ, Pichard AD, et al. Arterial remodeling after coronary angioplasty: A serial intravascular ultrasound study. Circulation 1996;94:35–43. 4. Morino Y, Limpijankit T, Honda Y, et al. Relationship between neointimal regrowth and mechanism of acute lumen gain during the treatment of in-stent restenosis with or without supplementary intravascular radiation. Cathet Cardiovasc Intervent 2003;58:162–167. 5. Hoffmann R, Mintz GS, Dussaillant GR, et al. Patterns and mechanisms of in-stent restenosis. A serial intravascular ultrasound study. Circulation 1996;94:1247–1254. 6. Kimura T, Nosaka H, Yokoi H, et al. Serial angiographic follow-up after Palmaz-Schatz stent implantation: comparison with conventional balloon angioplasty. J Am Coll Cardiol 1993;21:1557–1563. 7. Nobuyoshi M, Kimura T, Nosaka H, et al. Restenosis after successful percutaneous transluminal coronary angioplasty: serial angiographic follow-up of 229 patients. J Am Coll Cardiol 1988;12:616–623. 8. Preisack MB, Athanasiadis A, Voelker W, Karsch KR. Reliability of quantitative coronary angiography of the target lesion immediately and 1 day after coronary balloon and excimer laser angioplasty. J Am Coll Cardiol 1993;21:876–884. 9. Hanet C, Michel X, Schroeder E, Wijns W. Absence of detectable delayed elastic recoil 24 hours after percutaneous transluminal coronary angioplasty. Am J Cardiol 1993;71:1433–1436. 10. Foley DP, Deckers J, van den Bos AA, et al. Usefulness of repeat coronary angiography 24 hours after successful balloon angioplasty to evaluate early luminal deterioration and facilitate quantitative analysis. Am J Cardiol 1993;72:1341–1347.