Impact of septal myectomy on diastolic function in patients with obstructive hypertrophic cardiomyopathy

Background: The impact of septal myectomy on diastolic function in patients with obstructive hypertrophic cardiomyopathy is not well studied. Methods: A transcatheter hemodynamic study was performed before and 3 to 6 months after septal myectomy in 12 patients with obstructive hypertrophic cardiomyopathy (HCM). Results: Postoperative hemodynamic studies were done 4.4±1.2 months after myectomy. The left ventricular outflow tract peak-to-peak gradient decreased from 83.2±43.3 mmHg preoperatively to 11.6±4.3 mmHg after myectomy (P<0.00). The left ventricular diastolic time constant (Tau) was 64.2±26.1 ms before surgery and 42.2±15.7 ms postoperatively (P=0.029). The average left atrial pressure (LAP) decreased from 20.2±7.0 to 12.1±4.5 mmHg after myectomy (P=0.008). Pulmonary artery hypertension was present in 6 patients preoperatively and remained in 2 patients after myectomy. Mean pulmonary artery pressure decreased from 29.3±16.2 to 20±6.7 mmHg after surgery (P=0.05), and the systolic pulmonary artery pressure decreased from 46±26.9 to 30.5±8.3 mmHg (P=0.048). Pulmonary vascular resistance decreased from 5.7±4.1 to 3.6±1.6 wood after surgery (P=0.032). Conclusions: Septal myectomy improved left ventricular diastolic function and subsequently relieved the right ventricular congestion in patients with obstructive HCM.