Coronary lumen volume to myocardial mass ratio in primary microvascular angina.
J Cardiovasc Comput Tomogr. 2017 Nov;11(6):423-428. doi: 10.1016/j.jcct.2017.09.015. Epub 2017 Sep 22. Grover R1, Leipsic JA2, Mooney J1, Kueh SH1, Ohana M1, Nørgaard BL3, Eftekhari A3, Bax JJ4, Murphy DT1, Hague CJ1, Seidman MA5, Blanke P1, Sedlak T6, Sellers SL7.
BACKGROUND: Microvascular angina (MVA) is an incompletely understood clinical entity. Computational analysis of coronary Computed Tomography Angiography (CTA) has shown an association between low coronary lumen volume to myocardial mass (V/M) ratio and lower Fractional Flow Reserve values, independent of plaque measures. We hypothesized that low V/M ratio may be present in patients with MVA.
METHODS: A retrospective case-control analysis was performed using patients fulfilling guideline criteria for MVA with controls matched for age, gender, coronary risk factors and atherosclerotic plaque burden. V/M was extracted off site (Heartflow Inc; Redwood City, CA) employing allometric scaling laws that allow the definition of the coronary circulation beyond the epicardium. FFRCT values were calculated in the major epicardial coronary arteries for each group.
RESULTS: A total of 30 patients with MVA and 32 matched controls were included in the study. Mean total coronary lumen volume (2302 mm3 ± 109 vs 2978 mm3 ± 134, p < 0.001) and mean myocardial mass (90.4 g ± 13.7 vs 100.4 g ± 20.1, p = 0.029) were lower in MVA patients compared to controls. Mean V/M ratio was significantly lower in MVA compared to controls (25.6 mm3/g ± 5.9 vs 30.0 mm3/g ± 6.5, p = 0.007; c-statistic 0.69). V/M ratio did not differ significantly between subclasses of angina severity (p = 0.747). No difference in mean nadir FFRCT values was found between MVA and control groups in the LAD (0.86 ± 0.07 vs 0.83 ± 0.07, p = 0.154), LCX (0.90 ± 0.05 vs 0.90 ± 0.06, p = 0.240) and RCA (0.90 ± 0.04 vs 0.90 ± 0.03, p = 0.773) vessels.
CONCLUSION: Patients with microvascular angina demonstrate a significantly lower coronary CTA-derived coronary volume/myocardial mass ratio than asymptomatic controls.