BACKGROUND: Septal myectomy offers good results in patients with hypertrophic obstructive cardiomyopathy (HOCM). Over the past few years, the availability of genetic testing has increased. Whether certain types of mutations have better outcomes remains unknown. The aim of this study is to analyse short and mid-term outcomes of patients with HOCM who had a genetic test performed prior to septal myectomy.
METHODS AND RESULTS: All adult patients who underwent septal myectomy HOCM treatment between 2003 and 2019 were included. Patients with associated procedures and those without genetic testing were excluded. A total of 103 patients isolated septal myectomies were performed during that time period. Fifty-one of them (50%) had a genetic test. The mean follow-up of this cohort was 5.5 ± 3.7 years (completeness of follow-up= 92%). RESULTS: The mean age was 52 ± 13 and 16% of patients had a previous septal ablation before undergoing myectomy. Twenty-four patients (47%) had a no causative gene mutation identified, 14 patients (27%) had a MYBPC3 mutation, 7 patients (14%) were identified with a TNNT2 mutation, 4 patients (8%) had a MYH7 mutation and 3 patients (6%) were found to have other genetic mutations. One patient had 2 different genetic mutations (MYBPC3 and MYH7). Preoperative echocardiographic studies found a mean LVOT diameter of 22.8 ± 2.2mm, a mean interventricular septum thickness of 20.3 ± 4.2 mm and provoked LVOT gradient of 97 ± 48 mm Hg. The characteristics of patients according to their specific mutations are found in Table 1. Patients with TNNT2 mutation were younger (p=0.03). The number of previous septal ablation also differed among gene mutations (p=0.02). Twenty-four (47%) of patients were operated via a mini-thoracotomy. The mean CPB time was 74 ± 42 minutes and cross-clamp time was 56 ± 26 minutes. There was 1 mortality (2%) within 30 days of surgery. At follow-up, there was no difference in terms of septum thickness and provoked LVOT gradients between the various mutations (p=0.60 and p=0.79, respectively). There was no reintervention for septal ablation or myectomy during the follow-up period.
CONCLUSION: Our results suggest that the various gene mutations present with different characteristics. Mid-term results of septal myectomy appear to be good regardless of genetic mutation. Continued research in this field is warranted to better individualize patient care and large prospective studies are needed to confirm these results.