Background Although QRS duration >180 ms has prognostic value in adults with tetralogy of Fallot (TOF), its sensitivity to predict mortality is low. Fragmented QRS complexes, a simple measurement on ECG, are related to myocardial fibrosis and dysfunction in patients with TOF. Our objective was to determine whether QRS fragmentation predicts major outcomes in TOF.
Methods This multicentre study included adult patients with TOF from a prospective registry. Notches in the QRS complex in ≥2 contiguous leads on a 12-lead ECG, not related to bundle branch block, were defined as QRS fragmentation, which was classified as none, moderate (≤4 leads) or severe (≥5 leads). The primary and secondary outcomes were all-cause mortality and clinical ventricular arrhythmia, respectively.
Results A total of 794 adult patients with TOF (median age 27 years, 55% male; 52% no QRS fragmentation, 32% moderate, 16% severe) were included. During long-term (median 10.4 years) follow-up, 46 (6%) patients died and 35 (4%) patients had ventricular arrhythmias. Overall, 10-year survival was 98% in patients without fragmented QRS complexes, 93% in patients with moderate QRS fragmentation and 81% in patients with severe QRS fragmentation. In multivariable Cox hazards regression analysis, extent of QRS fragmentation (HR: 2.24/class, 95% CI 1.48 to 3.40, p<0.001) remained independently predictive for mortality, whereas QRS duration was not predictive (p=0.85). The extent of QRS fragmentation was also independently predictive for ventricular arrhythmia (HR: 2.00/class, 95% CI 1.26 to 3.16, p=0.003).
Conclusions The extent of QRS fragmentation is superior to QRS duration in predicting mortality in adult patients with TOF and may be used in risk stratification.
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Contributors All authors contributed to the conception and design of the study, and critical revision and final approval of this manuscript. JPB analysed and interpreted the data and drafted the manuscript under supervision of senior authors BJMM and BJB.
Funding This work was supported by the Netherlands Heart Institute and Nuts Ohra foundation. The work described in this study was carried out in the context of the Parelsnoer Institute. The Parelsnoer Institute is part of and funded by the Netherlands Federation of University Medical Centres.
Competing interests None declared.
Ethics approval Academic Medical Center, Amsterdam.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement All data from this study are available to the authors of this manuscript. Unpublished data are available upon request.