Effects of left ventricular mass on computed tomography derived fractional flow reserve in significant obstructive coronary artery disease.

Background: In significant obstructive coronary artery disease (SOCAD), a mismatch in assessment of severity of coronary artery stenosis may occur between invasive coronary angiography (ICA) and computed tomography (CT) derived fractional flow reserve (FFR). The present study aimed to identify the factors giving an FFR > 0.80 and leading to an underestimation of coronary artery severity in SOCAD vessels.

Methods: A total of 141 consecutive patients who underwent both CT angiography including FFR and ICA, the latter showing >75% coronary artery stenosis were evaluated. Vessels were divided into two groups according to FFR at the distal aspect of the vessel: FFR > 0.80 (n = 12) and FFR ≤ 0.80 (n = 153). Vessel morphology, plaque characteristics, left-ventricular (LV) wall thickness at each site of the myocardium, and LV mass were also assessed.

Results: LV myocardium-related parameters including LV wall thickness (base, middle, apex, average, and maximal), LV mass, and LV mass index were higher in FFR > 0.80, whereas vessel-related parameters including, vessel morphology and plaque characteristics were not significantly different between >0.80 and < 0.80. Vessel morphology and plaque characteristics had no effect on FFR, whereas maximum LV wall thickness, LV mass, and LV mass index influenced FFR. LV mass index was the strongest predictor of distal FFR > 0.80 with an area under the curve of 0.81, and an optimal cut-off value of 66.5 g/m (sensitivity 77.8%, specificity 89.6%).

Conclusions: The presence of a high LV mass is a major cause for underestimation of coronary artery severity on FFR in SOCAD vessels. LV myocardium-related parameters should be considered when interpreting numerical values of FFR.