Diagnostic Value of Mitral Z-Value in Mortality of Patients with Tetralogy of Fallot: A Seven-Year Experiment

Background: Tetralogy of Fallot (TF) in some Iranian patients is different in that the mitral z-value is significantly lower than normal. The present study was conducted to investigate the effect of the mitral Z-value on post-surgery mortality. Materials and Methods: The present retrospective analytical study was conducted on surgery candidate patients diagnosed with TF who had attended Shahid Modarres Hospital in Tehran between late March 2012 and late March 2019. Once the type of treatment and the need for surgery were decided and the mitral size and Z-value were determined, the patients underwent surgery, and then divided into two groups based on the outcome (death or discharge). Results: A total of 160 patients entered the study over seven years, of whom, 110 were discharged (group 1) and 50 died (group 2). There were no significant differences between the two groups in terms of gender. The patients' mean age was 8.96±8.09 years in the group 1 and 3.16±2.7 years in the group 2 (P<0.000). Mean mitral Z-value was -2.26±2.11 in the group 1 (ranging from -7.1 to +1.3) and -3.48±1.71 in the group 2 (ranging from -6 to -1.1), and Independent Sample Test showed no significant difference between the two groups (P=0.271). Conclusion: The mitral Z-value was significantly lower than normal in participating patients with TF, which could indicate hypo-plasticity of the left ventricle in Iranian patients with TF. No significant difference was found between the two groups in terms of surgical complications. In other words, the mitral Z-value had no effect on mortality of patients with TF.