Cardiac MRI predictors of good long-term outcomes in patients with repaired TOF

Abstract

Background: Risk stratification in patients with repaired tetralogy of Fallot (rTOF) have focused on poor clinical outcomes while predictors of a benign clinical course have not been characterized.

Objective: The goal of this study was to Identify cardiac magnetic resonance (CMR) markers of a good clinical course late after TOF repair.

Methods: Clinical and CMR data from the International Multicenter TOF Registry (INDICATOR) were analyzed. The primary outcome was time to the earliest occurrence of a composite of death, aborted sudden death, and sustained ventricular tachycardia (VT). The secondary outcome was time to the earliest occurrence of atrial arrhythmia, nonsustained VT, and NYHA class >II. Multinomial regression was used to identify predictors of the 3-category outcome: (a) good outcome, defined as freedom from the primary AND secondary outcomes at age 50 years; (b) poor outcome, defined as presence of the primary outcome before age 50 years; and (c) intermediate outcome, defined as not fulfilling criteria for good or poor outcomes.

Results: Among 1088 eligible patients, 96 had good outcome, 60 experienced poor outcome, and 932 had intermediate outcome. Patients were age 25.8±10.8 years at the time of the index CMR. Median follow-up was 5.8 years (IQR 3.0, 9.9) after CMR in event-free patients. By univariate analysis, smaller right ventricular (RV) end-systolic and end-diastolic volume index, smaller left ventricular end-systolic volume index, higher right and left ventricular ejection fraction, lower right and left ventricular mass index, and lower left ventricular mass/volume ratio were associated with good outcome. Multivariable modeling identified higher RV ejection fraction (OR 2.38 per 10% increase, P = .002) and lower RV mass index (OR 1.72, per 10 g/m² decrease, P = .002) as independently associated with good outcome after adjusting for age at CMR. Classification and regression tree analysis identified important thresholds associated with good outcome that were specific to patients age ≥37 years at the time of CMR; these were RV ejection fraction ≥42% and RV mass index <39 g/m².

Conclusions: Adults with rTOF and no more than mild RV dysfunction combined with no significant RV hypertrophy are likely to be free from serious adverse clinical events into their sixth decade of life and may require less frequent cardiac testing.