Multislice computed tomography to rule out coronary allograft vasculopathy in heart transplant patients

Abstract

Background: This study assessed if invasive coronary angiogram (CA) could be replaced by multislice (64- or 256-row) computed tomography (MSCT) to systematically rule out coronary allograft vasculopathy in heart transplant patients.

Methods: Electrocardiogram-gated contrast-enhanced MSCT (64-row for the first 25 patients and 256-row for the others) was compared with CA. MSCT parameters, adapted to the patient's weight, included 120 kV, 800 mAs, 0.625-mm slice thickness, and 0.42/0.27-second rotation time. The primary end point was the negative predictive value (NPV) of MSCT for the detection of significant (>50%) coronary stenosis. Secondary end points were the comparison of X-ray (mSv) and iodine contrast agent (ml) exposures.

Results: The study prospectively included 102 patients (mean age, 53±14 years). Transplantation occurred 6±5 years before inclusion. At CA, 41.8% had stenosis ≤50% and 8% had stenosis>50%. Among the 1,308 angiographic coronary segments ≥1.5 mm, 1,250 (95.6%) were evaluable by MSCT. The NPV of MSCT was 96.6% by patient analysis and 99.7% by segment analysis. The positive predictive value (PPV) was 45.5%. The total volume of contrast agent was 139±43 vs 91±12 vs 56±19 ml (p<0.05) with 64-row MSCT, 256-row MSCT, and CA, respectively. The effective radiation dose was higher using retrospective gating (17.8±5.5 mSv, p<0.05), but similar with prospective gating (6.2±1.9 mSv, p = 0.571) compared with CA (6.0±3.5 mSv).

Conclusion: Newer generations of MSCT (64- or 256-row) have a good NPV and may represent an alternative to invasive CA to rule out significant (>50%) coronary vasculopathy in heart transplant patients, despite a low PPV.