Coronary flow evaluation by TIMI frame count and magnetic resonance flow velocity in patients with coronary artery ectasia

Abstract

Purpose: Coronary artery ectasia (CAE) is defined as a dilatation of an arterial segment to a diameter at least 1.5 times that of the adjacent artery. It is characterized by slow flow, predisposing to thrombosis. The TIMI frame count (TFC) technique has been successfully used for the assessment of coronary flow velocity using coronary angiograms (CA). Our aim was to compare TFC with magnetic resonance peak flow velocity (PFV) for the evaluation of the coronary flow in patients with CAE.

Methods: Fifteen male patients with CAE, aged 45-60 yrs, and 15 age-matched male controls were studied by both techniques. Only patients without coronary obstructive disease were included. Magnetic resonance coronary angiography (MRA) was performed with a 1.5T scanner. The most ectatic part of the proximal 1/3 of the vessel involved was examined. Velocity-encoded MR images were acquired in a double oblique imaging plane, which was perpendicular to the same ectatic segment. The findings were compared with TFC results.

Results: Ten patients had RCA ectasia and five LAD ectasia. In CAE patients, peak flow velocity was 10.7 +/- 1.4 cm/sec in RCA and 11.4 +/- 2.3 cm/sec in LAD. TFC was 42.9 +/- 7.4 in RCA and 52.0 +/- 20.1 in LAD. In controls, peak flow velocity was 18.1 +/- 1.9 in RCA and 21.0 +/- 1.7 cm/sec in LAD. TFC was 20.4 +/- 1.59 in RCA and 19.8 +/- 1.12 in LAD. Controls had significantly higher peak flow velocity (p < 0.001) and lower TFC (p < 0.001) in both RCA and LAD, compared to patients with CAE. In patients with CAE, there was a negative correlation between PFV and TFC measurements (r = -0.74, p < 0.001).

Conclusion: Coronary flow in CAE patients can be assessed both by TFC and PFV. The noninvasive nature of PFV gives the opportunity for serial, easily repeatable, flow evaluation in these patients.