Comparison and Validity of Fragmented QRS (fQRS) Against Cardiac Magnetic Resonance (CMR) in Predicting Right Heart Function in Tetralogy of Fallot Patients After Reconstructive Surgery

Abstract

Background: Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease. Patients with repaired TOF (rTOF) expose to moderate to severe pulmonary regurgitation (PR), right ventricular (RV) dysfunction, and RV failure. Although cardiac magnetic resonance (CMR) provides details of RV function and structure, an electrocardiogram (ECG) is accessible and inexpensive. Objectives: We aimed to assess the correlation between clinical symptoms and ECG parameters with CMR findings. Methods: This cross-sectional study assessed the patients with rTOF who underwent CMR between May 2020 and September 2022 in Imam Reza Hospital. The signs and symptoms of rTOF were assessed, and a pediatric cardiologist interpreted ECG parameters. We considered CMR findings, clinical symptoms, and ECG parameters with CMR findings in rTOF. In addition, fragmented QRS (fQRS), the additional spikes within the QRS complex, was used to indicate conduction disturbance due to myocardial scar or fibrosis. Data were analyzed by SPSS version 18. Results: Among 42 patients with rTOF, 20 patients were male. Although the QT correction (QTc) had a significant correlation with CMR parameters, fQRS showed a positive correlation with right ventricular ejection fraction (RVEF) less than 47% (OR 2.06, 95% CI 1.45 - 2.93; P-value = 0.005), right ventricular end-diastolic volume (RVEDV) more than 150 mL/m2 (OR 4.4, 95% CI 2.03 - 9.5; P-value = 0), and right ventricular end-systolic volume (RVESV) more than 80 mL/m2 (OR 2.83, 95% CI 1.59 - 5.04; P-value = 0). We found a murmur in the clinical examination of 64.3% of patients. Our results showed that tachycardia and tachypnea were the most common signs in these patients. Surgery at a young age was significantly correlated to lower ascending aortic volume, right pulmonary artery size, left pulmonary artery size, right atrium and left atrium volume, and main pulmonary artery flow. Conclusions: Compared to other ECG parameters, fQRS could strongly predict RVESV, RVEDV, and RVEF as the right heart indexes. Besides, repair surgery at a younger age reduces the possibility of needing pulmonary valve replacement surgery at older ages. Therefore, clinicians should consider these issues in patients.