Safety and cost benefit of same-day discharge after percutaneous coronary intervention

Abstract

The present study shows that the major difference between long and short (diffuse and focal) ISR lesions is the stent size (determined by the IVUS stent area), not the length of the lesion per se. Longer ISR lesions were in smaller arteries, that is, those with a smaller external elastic membrane area and a smaller angiographic reference. The stent area may just be a surrogate for vessel size. Smaller arteries with smaller stent areas would have less tolerance for neointimal reaccumulation. The fi ndings in the present study help to explain why longer ISR lesions have higher recurrence rates after conventional treatment. Longer ISR lesions not only have a smaller minimum stent area, but also a greater focal increase in intimal hyperplasia area somewhere within the length of the area lesion. The probability of a greater focal increase in intimal hyperplasia area, when superimposed on a smaller stent area, results in a smaller follow-up minimum lumen area. The minimum lumen area at follow-up was the fi rst preselected IVUS end point of the study. Previous studies have related ischemia during exercise testing and an abnormal coronary fl ow (measured using the Doppler fl ow wire) to the IVUS minimum lumen CSA. 6,7 In the present study: (1) patients in the Long WRIST group had smaller stent areas, (2) the postintervention minimum stent area correlated with ISR length, and (3) the postintervention minimum stent area was the only independent predictor of the absolute minimum lumen area at follow-up. The increase in mean intimal hyperplasia area was the second preselected IVUS end point of the study. The increase in mean intimal hyperplasia area is a marker of biologic activity of an ISR lesion. In the present study: (1) patients with longer ISR lesions had a greater increase in maximum intimal hyperplasia area; and (2) patients with longer ISR lesions had a greater maximum/minimum follow-up intimal hyperplasia area. The ratio of the maximum/minimum follow-up intimal hyperplasia area, which also correlated with ISR length, is an index of the axial heterogeneity of the neointimal recurrence. 8 The heterogeneity of the neointimal response may be one of probability, related to the length of the ISR lesion. This study analyzed the serial intravascular ultrasound findings of 40 placebo patients from WRIST (ISR length 10 to 47 mm) with 34 placebo patients from Long WRIST (ISR length 36 to 80 mm) in an attempt to understand why longer ISR lesions have a greater probability of recurrence following conventional treatment. The 2 main factors contributing to the recurrence of stent restenosis in longer lesions are smaller stent size and a more heterogeneous proliferative response.