Vectorcardiography signs of a failing Fontan: Heart rate, PR interval, RtQRSvm, QRSvm and SPQRS-T angle as noninvasive markers of late Fontan complications and mortality.

ABSTRACT

BACKGROUND: Limited data exists on interpreting vectorcardiography (VCG) parameters in the Fontan population. OBJECTIVE: The purpose of this study was to demonstrate the associations between ECG/VCG parameters and Fontan failure (FF). METHODS/RESULTS: 107 patients with a Fontan operation after 1990 and without significant ventricular pacing were included. FF and Fontan survival (FS) groups were compared. The average follow-up after Fontan operation was 11.8 years ±7.1 years. 14 patients had FF (13.1%) which was defined as having protein-losing-enteropathy (1.9%), plastic bronchitis (2.8%), Fontan takedown (1.9%), heart transplant (5.6%), NYHA class III-IV (2.8%) or death (0.9%). A 12­lead ECG at last follow up or prior to FF was assessed for heart rate, PR interval, QRS duration, Qtc and left/right sided precordial measures (P-wave, QRS and T-wave vector magnitudes, spatial P-R and QRS-T angles). Transthoracic echocardiogram evaluated atrioventricular valve regurgitation and ventricular dysfunction at FF or last follow up. A cox multivariate regression analysis adjusted for LV dominance, ventricular dysfunction, HR, PR, QTc, Pvm, QRSvm, SPQRST-angle, RtPvm, RtQRSvm and RtTvm. Ventricular dysfunction, increased heart rate and prolonged PR interval were significantly associated to FF at the multivariate analysis. ROC analysis and Kaplan-meier analysis revealed an increased total mortality associated with a heart rate > 93 bpm, PR interval > 155 mv, QRSvm >1.91 mV, RtQRSvm >1.8 mV and SPQRST angle >92.3 mV with p values <0.001 to 0.018. CONCLUSION: We demonstrate the importance of ECG/VCG monitoring in the Fontan population and suggest specific indicators of late complications and mortality.