Drug-coated versus conventional balloons for side branch treatment in coronary bifurcation lesions: an optical coherence tomography substudy of the OCVC-BIF randomised trial

BACKGROUND: Coronary bifurcation lesions remain prone to side branch (SB) ostial restenosis. Kissing balloon inflation (KBI) is the standard of care for provisional stenting, but it induces mechanical injury. Drug-coated balloons (DCBs) may pharmacologically inhibit neointimal hyperplasia to improve long-term patency. AIMS: We sought to evaluate mechanistic vascular healing and luminal changes of the SB after adjunctive SB-DCB versus SB-conventional balloon treatment using high-resolution serial optical coherence tomography (OCT). METHODS: The randomised OCVC-BIF trial compared adjunctive SB-DCB (n=149) with non-DCB treatment (n=150) following main vessel stenting and protocolled KBI. The present prespecified study was restricted to those patients who completed analysable follow-up OCT pullbacks (n=221). Endpoints included the SB volume change and the main vessel stent healing parameters. RESULTS: There was no significant difference in the ostium, minimum SB area, or SB volume between the DCB and non-DCB groups following percutaneous coronary intervention (PCI). Serial OCT analysis showed that the DCB group exhibited a lumen volume gain at the SB of 0.14±5.64 mm3 from post-PCI to 9-month follow-up, whereas the non-DCB group showed a mean loss of 2.15±9.51 mm3. Although this difference reached statistical significance in the prespecified parametric analysis (p=0.042), in the sensitivity analysis using the Wilcoxon rank-sum test, the difference was attenuated (0.45 [interquartile range [IQR] -3.83, 4.00] in DCB vs -0.65 [IQR -5.00, 2.50] in non-DCB; p=0.093). While in the DCB group, the SB lumen volume change from immediately after PCI to follow-up was not statistically significant (p=0.81), the non-DCB group demonstrated a statistically significant reduction in SB lumen volume (p=0.03). At 9 months, the incidence of uncovered and malapposed struts was low and comparable between groups across all segments. CONCLUSIONS: Adjunctive SB-DCB treatment after KBI showed no adverse effect on main vessel stent healing and a possible signal towards preservation of the SB lumen. These findings may support the mechanistic feasibility of this strategy in selected bifurcation lesions. (Japan Registry of Clinical Trials: jRCTs052200077).