Mitral valve Z value in Iranian patients with tetralogy of Fallot

Background: Tetralogy of Fallot (TOF) refers to a condition in which left ventricular volume is normal or slightly less than normal. Given the differences observed in some Asian patients with TOF, the present study was conducted to investigate left heart by determining Z-scores for the mitral valve in Iranian patients with TOF. Methods: Eligible subjects in this prospective descriptive study comprised all patients with TOF presenting to Shahid Modarres Hospital in Tehran from March 2012 to March 2015 and diagnosed as the candidates for surgery. After determining the need for surgery and the therapeutic method required, the mitral valve size and Z-scores were calculated. We analyzed sex, age, body surface area (BSA), mitral size (in 2-chamber and 4-chamber view), mitral Z-score, other cardiac anomalies, number of surgery and previous surgery. Results: Of a total of 80 patients included in the study over 3 years, 29 (36.3%) were male and 51 (63.8%) were female. The mean age of the patients was 7.15±3.37 years and their mitral size was found to be 10-27 mm (16.2±5.99 mm) using echocardiography. Z-scores of the mitral valve were also obtained as -3.09±2.11, ranging between -7.1 SD and +1.3 SD. 58 (72.5%) patients have only TOF and 22 (27.5%) with other cardiac anomalies. 45 patients were for first time underwent surgery and 22 patients for second time, 12 patients for three time and 1 for forth. Of a total of 35 patients had previous surgery, the most common were shunt 15 (42.9%) and then tetralogy of Fallot total correction (TFTC) in 12 (34.3%). Of a total of 80 patients, 59 (73.8%) underwent TFTC, 17 (21.3%) under pulmonary valve replacement and 4 (5%) shunt. Conclusion: Z-scores of the mitral valve were found to be significantly below the normal value, (i.e. 0±2 SD), in the study patients, suggesting the risk of hypoplastic left heart syndrome in Iranian patients with TOF, nevertheless, the type of TOF examined in these patients might have been different from those observed in other races and regions.