Natural history of small and medium-sized side branches after coronary stent implantation

Our purpose was to identify angiographic and procedural predictors for acute and late side branch occlusion after coronary stent implantation.

We evaluated 185 patients with 185 lesions with 255 side branches with a mean reference diameter of 1.45 +/- 0.38 mm; the lesions were covered by 240 stents. Angiographic follow-up was completed in 99 patients with 133 side branches 206 +/- 120 days after stent implantation and clinical follow-up was available in 136 patients. Side branch occlusion (SBO) was defined as a Thrombolysis In Myocardial Infarction (TIMI) flow < or =1.

Acute SBO affected 54 side branches in 49 patients and was not associated with death or Q-wave infarction. By logistic regression, independent predictors for acute SBO were (1) the reference side branch diameter (RLD) at baseline (OR [odds ratio] 0.217, 95% CI 0.07-0.67, P =.008); (2) an ostial side branch stenosis before stenting (OR 2.96, 95% CI 1.26-6.95, P =.013); (3) the involvement of the side branch origin within the lesion of the parent vessel (OR 2.77, 95% CI 1.17-6.57, P =.021); and (4) the balloon-to-artery ratio (OR 4.66, 95% CI 1.18-18.42, P =.028). Among the initially occluded side branches, 81.8% were spontaneously reperfused at follow-up. Late SBO involved 12% of the side branches without impaired antegrade flow after stenting and was predicted by the initial RLD of the side branch (OR 0.07, 95% CI 0.01-0.8, P =.032). Chronic SBO occurred in 13.5% of cases and was also predicted by the baseline RLD (OR 0.13, 95% CI 0.02-0.8, P =.028).

Acute SBO after stenting occurred in 21.2% of cases and had a benign course. Most acutely occluded side branches underwent late spontaneous reperfusion. A baseline side branch diameter >1.4 mm predicted a preserved antegrade flow immediately after stent implantation, as well as during follow-up.