Prognostic Cardiac Biomarkers and Tetralogy of Fallot Score: Do they Predict Outcomes in Intracardiac Tetralogy of Fallot Repair?

One of the most common cyanotic congenital heart diseases seen in India is the tetralogy of Fallot (TOF). The presence of chronic hypoxia leads to increased susceptibility to ischemia and infections. The postoperative morbidity and mortality can be predicted earlier, by incorporating various biochemical markers in pre-operative workup, which can minimize post-operative mechanical ventilation and intensive care unit (ICU) stay. We aimed to study 11 different cardiac biomarkers and calculate the All India Institute of Medical Sciences (AIIMS) score as a prognostic marker in TOF patients. After obtaining Institute Ethics Committee approval from the Hospital Ethics Committee with Indian Council of Medical Research (ICMR) Trial No: 5/4/1-1/08-NCD-II and written informed consent, a prospective and observational study was conducted on 150 patients with TOF undergoing elective intra cardiac repair (ICR) divided into two groups. Anesthetic and surgical management was standardized for all patients as per institutional protocol. The data were analyzed in STATA software. The sample size was calculated on the basis of the area under the curve for various biomarkers shown in the previous literature reviews. There was a positive correlation between the Endothelin levels 48 h after bypass and post-operative outcome measures such as the duration of inotropes, duration of ventilation, and duration of ICU stay. Pre-cardiopulmonary bypass serum tumor necrosis factor-alpha (TNF-α) showed a significant correlation with mortality in group I patients (P = 0.009) and group II patients (P < 0.05). Intragroup comparison in survivors showed significant changes with time in lactate trends. The mean initial post-operative lactate was significantly lower for survivors than for non-survivors. In addition, the serial mean lactate decreased progressively in all surviving patients compared with non-survivors diagnostic receiver operating characteristic curve for the pressure of oxygen. The four biomarkers, namely, Endothelin, TNF-α, BNP, and base excess, were found to be highly sensitive and specific. Using these biomarkers, a score of 2.73 (the AIIMS TOF score) is considered morbid in patients post-ICR in the ICU. The chances of mortality are high, with a sensitivity of 96.9% and specificity of 89.2%.