Original Title: Optimal Strategy for Provisional Side Branch Intervention in Coronary Bifurcation Lesions3-Year Outcomes of the SMART-STRATEGY Randomized Trial. Reference: Young Bin Song et al. J Am CollCardiolIntv. 2016;9(6):517-526.
This study compared the long term outcomes of the conservative strategy vs. the aggressive strategy for provisional side branch intervention in coronary bifurcations. It has already been reported that the 2 stent technique is not superior to the provisional stent for the treatment of bifurcations. However, the optimal criterion for side branch stenting, having initially opted for a provisional stent, has not been established yet.
After main vessel stenting, patients were randomized 1:1 to a conservative strategy vs. an aggressive strategy to treat the side branch; these criteria were applied differently.
Different criteria applied for the initiation of SB intervention after main vessel stenting in the conservative and aggressive groups were Thrombolysis In Myocardial Infarction flow grade lower than 3 versus a stenosis diameter >75% for non–left main bifurcations, and a stenosis diameter >75% versus a stenosis diameter >50% for left main bifurcations. The primary endpoint was target vessel failure (TVF), defined as a composite of cardiac death, spontaneous myocardial infarction, or target vessel revascularization at 3 years. For left main bifurcations, when stenosis diameter >75% (conservative strategy) versus a stenosis diameter >50% (aggressive strategy). After ballooning and kissing, a second stent was implanted only with persisting>50% stenosis or dissection in the conservative strategy, or >30% stenosis or dissection in the aggressive strategy.
For non-left main lesions, side branch stenting was applied when TIMI flow was lower than 3 for the conservative strategy, or with a residual stenosis of >75% for the aggressive strategy.The study randomized 258 patients; 114 of these (44%) were left main bifurcation cases.
Primary end point was target vessel failure defined as a combination of cardiac death, spontaneous MI, and target vessel revascularization at 3 years. At the end of the follow up period, the primary end point was observed in 11.7% in the conservative strategy arm vs. 20.8% in the aggressive strategy arm (p=0.049). Although there were no differences at one year (9.4% vs. 9.2%; p = 0.97), between years 1 and 3, there was a significantly lower incidence of target vessel failure with the conservative strategy (2.6% vs. 12.7%; p = 0.004).
Crossover to the 2 stent technique was an independent predictor of events (HR: 5.42, CI 95% 2.03 to 14.5; p < 0.001). The left main stenosis arm showed identical results.
Conclusion
A conservative strategy compared to an aggressive strategy to treat a bifurcation with side branch stenting is associated with long term benefits.
Editorial Comment
This study regards the provisional stenting technique as standard treatment (including the left main coronary artery) and gives us objective tools to decide for or against side branch stenting. The study does not take into account more subjective parameters, as we normally do in the cath lab, such as angina mentioned by patients.
Note that the low events rate in the conservative arm gave the study low statistical power (42%), which makes it impossible to make conclusions about small subgroups such as a dominant left circumflex cases.