Can Abbreviated Cardiac Magnetic Resonance Imaging Adequately Support Clinical Decision Making After Repair of Tetralogy of Fallot?

Quantification of pulmonary regurgitation (PR), pulmonary flow distribution, and ventricular function is important for clinical surveillance in repaired Tetralogy of Fallot (TOF). Cardiovascular magnetic resonance (CMR) is the established reference, but cost, test duration, and patient discomfort are potential limitations to its serial use. We investigated whether an Abbreviated CMR protocol would alter clinical decisions in TOF from those that would have been made using a full protocol. Patients > 7 years with repaired TOF were identified. CMR was performed according to standard complete imaging protocol. CMRs were prepared in two ways, Full and Abbreviated and submitted for review by two imaging specialists. In conjunction with clinical information and case-specific quantitative CMR data (PR fraction, ventricular volumes, ejection fraction, branch pulmonary artery flow), Full and Abbreviated image sets were anonymized and uploaded for review. For the first half, Imager 1 received Abbreviated, and Imager 2 Full and for the remaining, Imager 1 received Full and Imager 2 received Abbreviated. Blinded to the other's choices, Imagers provided clinical decisions. Inter-rater agreement for each decision was measured. In all, 124 studies from 80 patients (mean 17.8 years) were analyzed. For 'intervention versus no-intervention' decision, the inter-rater agreement was strong [κ 0.75, p < 0.0001, 95% CI (0.630, 0.869)]. Agreement for recommended timing of follow-up imaging was good (κ 0.64, p < 0.0001, 95% CI (0.474, 0.811)] in the 'no-intervention' group. When raters were asked whether or not further imaging was necessary, agreement was modest [κ 0.363 (p < 0.0001), 95% CI (0.038, 0.687)]. In conclusion, Abbreviated CMR yield decisions for clinical care similar to those made using the standard full protocol. These results suggest a potential enhancement of clinical practice in which efficiency and cost saving might be achieved using Abbreviated CMR for routine follow-up surveillance of TOF.