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BACKGROUND: Atrial fibrillation (AF) presents a potential challenge when performing coronary computed tomography angiography (CTA). To date, there is no ideal protocol for CTA in patients with AF. We sought to design a protocol for single-heartbeat coronary CTA in patients with AF. METHODS: We enrolled 32 patients with AF and a very low probability of coronary artery disease who were referred for CTA to assess pulmonary vein anatomy for catheter ablation. A 256-slice scanner was used. Twelve patients underwent CTA using non-gated triple Flash (NGTF) consisting of three prospective electrocardiogram (ECG)-triggered helical scans with a built-in ECG simulator, while retrospectively gated helical (RGH) was used in 20 patients. Radiation dose, and a 4-point scale was used to assess coronary artery image quality between CTA scan modes. RESULTS: A total of 96 vessels were analyzed. The 4-point score showed no significant differences between the RGH and NGTF scans (2.9 ± 0.6 vs. 2.8 ± 0.8, respectively; p = 0.34). The number of coronary arteries with extensive blurring did not significantly differ between the protocols, and included four vessels (6.6%) in RGH vs. three vessels (8.3%) in NGTF (p = 0.5). Radiation exposure was significantly higher with RGH scans, with a dose-length product of 835 ± 146 mGy compared with 382 ± 35 mGy for NGTF (p < 0.0001). CONCLUSIONS: Single heartbeat NGTF CTA has comparable image quality and significantly lower radiation dose compared to RGH scans in patients with AF. Whether this protocol can be used in next-generation computed tomography scanners has yet to be determined.
RESUMO
PURPOSE: Graftability of the left anterior descending artery (LAD) has important prognostic value for coronary artery bypass graft (CABG) surgery. However, with a chronic total occlusion (CTO) of the LAD, invasive coronary angiography (ICA) may be insufficient to determine its graftability. We evaluated the role of coronary computed tomographic angiography (CTA) in the assessment of CTO and LAD graftability when the distal vessel segment was incompletely visualized by ICA. MATERIALS AND METHODS: We enrolled 31 patients with equivocal eligibility for CABG due to CTO of the LAD with poor distal flow defined by ICA. Patients with LAD diameters ≥1.5 mm by CTA underwent CABG surgery, and the vessel diameter was reassessed intraoperatively. RESULTS: The mean age was 54±14 years. Seven patients (23%) had suitable LAD targets on CTA and underwent successful CABG. Another 24 patients (77%) had nongraftable LADs. Patients with a graftable LAD showed no significant difference between mean LAD diameter measured by CTA and during surgery (1.6±0.3 vs. 1.5±0.3 mm, P=0.21). The preoperative left ventricular ejection fraction was not significantly different between groups (35%±8% vs. 35%±7%, P=0.2). However, after a mean follow-up of 21±7 months, left ventricular ejection fraction was significantly higher in vascularized patients (41%±5.8% vs. 34%±8%, P=0.01, respectively). Six of 7 patients had patent LAD grafts on CTA at 1-year follow-up. CONCLUSION: CTA may provide valuable information about chronically occluded LAD size and graftability when ICA is inconclusive.
