There are no guidelines regarding the most appropriate approach for provisional side branch (SB) intervention in left main (LM) bifurcation lesions.

The present prospective, randomized, open-label, multicenter trial compared conservative vs aggressive strategies for provisional SB intervention during LM bifurcation treatment. Although the trial was designed to enroll 700 patients, it was prematurely terminated due to slow enrollment. For 160 non-true bifurcation lesions, a 1-stent technique without kissing balloon inflation was applied in the conservative strategy, whereas a 1-stent technique with mandatory kissing balloon inflation was applied in the aggressive strategy. For 46 true bifurcation lesions, a stepwise approach was applied in the conservative strategy (after main vessel stenting, SB ballooning when residual stenosis> 75%; then, SB stenting if residual stenosis> 50% or there was a dissection). An elective 2-stent technique was applied in the aggressive strategy. The primary outcome was a 1-year target lesion failure (TLF) composite of cardiac death, myocardial infarction, or target lesion revascularization.

Among non-true bifurcation lesions, the conservative strategy group used a smaller amount of contrast dye than the aggressive strategy group. There were no significant differences in 1-year TLF between the 2 strategies among non-true bifurcation lesions (6.5% vs 4.9%; HR, 1.31; 95%CI, 0.35-4.88; P=.687) and true bifurcation lesions (17.6% vs 21.7%; HR, 0.76; 95%CI, 0.20-2.83; P=.683).

In patients with a LM bifurcation lesion, conservative and aggressive strategies for a provisional SB approach have similar 1-year TLF rates.