Extended myectomy for hypertrophic obstructive cardiomyopathy patients with midventricular obstruction.

OBJECTIVES: Surgical strategies for patients with midventricular obstruction remain underappreciated. We sought to assess clinical and haemodynamic results, summarize the surgical technique of extended myectomy and provide reliable pre- and intraoperative methods of evaluating patients with midventricular obstruction. METHODS: The preoperative evaluation process, intraoperative surgical strategy and early outcomes were thoroughly reviewed in 40 patients with midventricular obstruction. RESULTS: Isolated transaortic myectomy was conducted in 38 (95.0%) patients, and 2 (5.0%) other patients with an apical aneurysm were treated with a combined transaortic and transapical myectomy. The median resection length of the removed muscle was 50mm (45-55 mm), approximately 5mm more than the obstruction length measured using preoperative transthoracic echocardiography. There were no early or late deaths, complete heart blocks or iatrogenic septal perforations in our study series with a median follow-up time of 19 months (13-54 months). Instantaneous pressure gradients at the subaortic level decreased from 70.5mmHg (51-89.5 mmHg) preoperatively to 7.7mmHg (6-11 mmHg) (P < 0.001) at the most recent evaluation and at the midventricular level from 61.0mmHg (42.8-85.5 mmHg) to 8.5mmHg (6.3-11.8 mmHg) (P < 0.001). In all patients, the New York Heart Association functional classifications improved, with a better haemodynamic status. CONCLUSIONS: Transaortic myectomy can be extended to the midventricular level, improving haemodynamic status and yielding satisfactory early outcomes in selected patients. Additional transapical myectomy should be considered in patients with a long obstruction, limited exposure of the midventricular area or a concomitant apical aneurysm.