Incidence and periprocedural outcomes of heparin-induced thrombocytopenia in on-pump vs off-pump coronary artery bypass grafting patients – analysis from 2016–2019 national inpatient sample

Abstract Background Heparin administered after Coronary Artery Bypass Grafting (CABG) can cause Heparin induced thrombocytopenia (HIT) leading to bleeding or thromboembolic complications. Despite its low incidence, HIT can lead to increased morbidity and in-hospital mortality. Purpose To study the incidence and periprocedural outcomes of HIT in On-pump vs Off-pump CABG patients. Methods This is a retrospective observational study involving index hospitalizations for CABG between January 1 2016–December 31 2019 from the National Inpatient Sample, the largest all-payer public database of hospital care data in the United States. Our study population included discharged adult patients (≥18 years) hospitalised for CABG using ICD-10 codes (validated in previous studies). Confounders were adjusted using Multivariable Regression Analysis. Results During 2016–2019, there were 100,715 principal hospitalizations for On-pump and 25,956 for Off-pump CABG. Mean age was 74.6±13.2 years. The incidence of HIT in the On-pump cohort was 0.33% (n=333) and 0.33% (n=85) in the Off-pump cohort. The On-pump cohort had 76% (n=76,543) males, 24% (n=24172) females (p<0.0001) and the Off-pump cohort had 74.5% (n=19337) males, 24.5% (n=6359) females (p<0.001). The On-pump cohort had 78.2% Whites, 7.1% Blacks, 7.7% Hispanics, and 7% other races, while the Off-pump cohort had 76.9% Whites, 7.8% blacks, 8.9% Hispanics and 6.4% other races. A total of 42.9% hospitalizations in the On-pump cohort had a Charlson Comorbidity Index (CCI) of three or higher and it was 43.5% hospitalizations in the Off-pump cohort. In-hospital mortality in the On-pump cohort was 1.6% and 2% in the Off-pump cohort. Compared to the non-HIT cohort, On-pump HIT cohort had more females (31.2% vs 24%, p=0.02), were older (mean age: 67.2 years vs 65.7 years; p=0.006), had higher CCI of three or higher (65.8% vs 42.8%, p<0.001), longer LOS (22.2 days vs 9.2 days, p<0.001) with higher in-hospital mortality (13.5% vs 1.5%, p<0.001). Multivariate regression analysis showed HIT cohort had higher odds of in-hospital mortality than non-HIT cohort (aOR: 8; 95% CI: 5.7, 11.2; p<0.001) after controlling for age, sex, race, hospital region and status, income, insurance status and CCI. The Off-pump HIT cohort had similar incidence of females (26% vs 27%, p=0.710), were older (mean age: 68 years vs 65.8 years; p=0.045), had higher CCI of three or higher (65.9% vs 43.5%, p<0.001), had longer LOS (22.9 days vs 9.4 days, p<0.001) with higher in-hospital mortality (10.6% vs 2%, p<0.001) compared to the non-HIT cohort. Multivariate regression analysis showed HIT cohort had higher odds of in-hospital mortality than non-HIT cohort (aOR: 4.7; 95% CI: 2.3, 9.5; p<0.001) after controlling for age, sex, race, hospital region and status, income, insurance status and CCI. Conclusion Our study observed that in-hospital mortality in patients with HIT was significantly high compared to patients without HIT after undergoing On-pump or Off-pump CABG. Funding Acknowledgement Type of funding sources: None.