Impact of cardiac rhythm abnormality on hospital outcomes of patients with hypertrophic cardiomyopathy

Background Serious cardiac arrhythmias [atrial fibrillation/flutter (AFF), and ventricular tachycardia/fibrillation (VTF)] are associated with adverse outcomes in general population of patients with hypertrophic cardiomyopathy (HCM). Purpose We aimed to evaluate the impact of such rhythm abnormalities on in-hospital outcomes of adults with HCM. Methods The National Inpatient Sample reported 45,305 admissions for adults with HCM during a two-year period (2016–2017). Among them, 21,220 patients (47%) also had AFF and/or VTF. Baseline characteristics and in-hospital outcomes of the two groups were compared. Multivariable logistic regression analysis was used to assess the independent impact of rhythm abnormalities on in-hospital outcomes of HCM patients. Results HCM patients with arrhythmias were older (68±26 vs 64±29 years), were more often male (43% vs 36%), and had higher prevalence of congestive heart failure (45% vs 28%), chronic kidney disease (27% vs 22%), hyperlipidemia (52% vs 48%), obstructive sleep apnea (17% vs 13%), chronic obstructive pulmonary disease (22% vs 18%) and thyroid disease (19% vs 16%) [Table 1, all p<0.001]. Hospital mortality was significantly higher among those with arrhythmias (4.7% vs 2.7%, p<0.05). Multivariate logistic regression analysis identified arrhythmias as an independent predictor of in-hospital mortality (adjusted odds ratio=1.51, 95% confidence interval=1.19–1.91, p=0.001), increased mean length of stay (Δ +0.75 days, p<0.001) and increased mean total hospital cost (Δ +$18,263, p<0.001). Conclusion Adults with HCM and AFF and/or VTF are older and have higher prevalence of comorbid conditions. Presence of such rhythm abnormalities is an independent predictor of higher mortality, length of stay and total cost in HCM adults admitted to hospital.