Results of ventricular septal myectomy and hypertrophic cardiomyopathy (from Nationwide Inpatient Sample [1998-2010])

Abstract

Ventricular septal myomectomy (VSM) is the primary modality for left ventricular outflow tract gradient reduction in patients with obstructive hypertrophic cardiomyopathy with refractory symptoms. Comprehensive postprocedural data for VSM from a large multicenter registry are sparse. The primary objective of this study was to evaluate postprocedural mortality, complications, length of stay (LOS), and cost of hospitalization after VSM and to further appraise the multivariate predictors of these outcomes. The Healthcare Cost and Utilization Project's Nationwide Inpatient Sample was queried from 1998 through 2010 using International Classification of Diseases, Ninth Revision, procedure codes 37.33 for VSM and 425.1 for hypertrophic cardiomyopathy. The severity of co-morbidities was defined using the Charlson co-morbidity index. Hierarchical mixed-effects models were generated to identify independent multivariate predictors of in-hospital mortality, procedural complications, LOS, and cost of hospitalization. The overall mortality was 5.9%. Almost 9% (8.7%) of patients had postprocedural complete heart block requiring pacemakers. Increasing Charlson co-morbidity index was associated with a higher rate of complications and mortality (odds ratio 2.41, 95% confidence interval 1.17 to 4.98, p = 0.02). The mean cost of hospitalization was $41,715 ± $1,611, while the average LOS was 8.89 ± 0.35 days. Occurrence of any postoperative complication was associated with increased cost of hospitalization (+$33,870, p <0.001) and LOS (+6.08 days, p <0.001). In conclusion, the postoperative mortality rate for VSM was 5.9%; cardiac complications were most common, specifically complete heart block. Age and increasing severity of co-morbidities were predictive of poorer outcomes, while a higher burden of postoperative complications was associated with a higher cost of hospitalization and LOS.