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 50 mm (45-55 mm), approximately 5 mm 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 70.5 mmHg (51-89.5 mmHg) preoperatively to 7.7 mmHg (6-11 mmHg) (P < 0.001) at the most recent evaluation and at the midventricular level from 61.0 mmHg (42.8-85.5 mmHg) to 8.5 mmHg (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.