Identification of Coronary Artery Side Branch Supplying Myocardial Mass That May Benefit From Revascularization

Abstract

OBJECTIVES: The authors sought to identify whether a coronary side branch (SB) is supplying a myocardial mass that may benefit from revascularization. BACKGROUND: The amount of subtending myocardium and physiological stenosis is frequently different between the main vessel (MV) and SB. METHODS: In this multicenter registry, 482 patients who underwent coronary computed tomography angiography and fractional flow reserve (FFR) measurement were enrolled. The % fractional myocardial mass (FMM), the ratio of vessel-specific myocardial mass to whole myocardium, was assessed in 5,860 MV or SB consisting of 2,930 bifurcations. Physiological stenosis was defined by fractional flow reserve (FFR) <0.80. Myocardial mass that may benefit from revascularization was defined by %FMM >/=10%. RESULTS: In per-bifurcation analysis, MV supplied a 1.5- to 9-fold larger myocardial mass compared with SB. Unlike left main bifurcation (n = 482), only 1 of every 5 non-left main SB (n = 2,448) supplied %FMM >/=10% (97% vs. 21%: p < 0.001). SB length >/=73 mm could estimate %FMM >/=10% (c-statistic = 0.85: p < 0.001). In 604 vessels interrogated by FFR, diameter stenosis was similar (p = NS), but %FMM >/=10%, FMM/minimal luminal diameter, and frequency of FFR <0.80 was higher in MV compared with SB (p < 0.001, all). Generalized estimating equations modeling demonstrate that vessel diameter, left myocardial mass, and FFR were not (p = NS), but SB length >/=73 mm and left main bifurcation were significant predictors for %FMM >/=10% (p < 0.001). CONCLUSIONS: Compared with MV, SB supplies a smaller myocardial mass and showed less physiological severity despite similar stenosis severity. SB supplying a myocardial mass of %FMM>/=10%, which may benefit revascularization could be identified by vessel length >/=73 mm. Pre-procedural recognition of these findings may guide optimal revascularization strategy for bifurcation.