Outcome of nonobstructive residual dissections detected by intravascular ultrasound following percutaneous coronary intervention.

The purpose of this study was to assess the outcome of nonobstructive (or non-flow-limiting) residual dissection (RD) after percutaneous coronary intervention. Results of 124 consecutive native coronary lesions with angiographic nonobstructive RD in 97 patients (RD group) were compared with outcomes of 124 lesions without RD in 100 patients (non-RD group), whose characteristics were matched with those of the RD group. RD occurred after stent implantation (81 of 124 lesions, 65%) or balloon angioplasty (43 of 124 lesions, 35%). Angiographic types of RD were type A in 8 lesions (6%), B in 101 (82%), and C in 15 (12%). Stents were implanted in 65% of the lesions in each group. Clinical success (94% in RD group vs 95% in non-RD group, p = 0.77) and the in-hospital major adverse cardiac event rates were found to be similar in the 2 groups (6% vs 3%, respectively; p = 0.33). The late angiographic and clinical outcomes were also comparable. By intravascular ultrasound (IVUS) evaluation of the dissections in the RD group, area stenosis correlated with the incidence of in-hospital major adverse cardiac events (p = 0.023), whereas the final minimal lumen area correlated inversely with the occurrence of restenosis (p = 0.011). An area stenosis > or =58% was the best predictor for the incidence of in-hospital major adverse cardiac events (sensitivity 0.68, specificity 0.68). Most nonobstructive RDs are "favorable" and do not need stent implantation. IVUS evaluation identifies "unfavorable" nonobstructive (or non-flow-limiting) dissections that might be prone to acute occlusion. Nonobstructive dissections can be left untreated when final IVUS reveals an area stenosis of < 60% at the site of a dissection.