Outcomes Associated With Early vs. Delayed Invasive Strategy in NSTEMI Complicated by High Degree AV Block: A Nationwide Analysis.

Background: High degree atrioventricular block (HDAVB) is an uncommon complication of non-ST-segment elevation myocardial infarction (NSTEMI) that frequently necessitates pacemaker implantation. This contemporary analysis compares need for pacemaker implantation based on the timing of intervention in acute NSTEMI complicated by HDAVB.Methods: We used 2016-2017 National Inpatient Sample database to identify admissions with NSTEMI and HDAVB. Time to coronary intervention from initial admission was used to segregate the admissions into two groups: early invasive strategy (EIS) (<24 hours) and delayed invasive strategy (DIS) (>24 hours). Multivariable linear and logistic regression analysis was performed to compare in-hospital outcomes among the two groups.Results: Out of 949,984 NSTEMI related admissions, coexistent HDAVB was present in 0.7% (n=6725) patients. Amongst those, 55.61% (n=3740) hospitalizations included invasive intervention (EIS=1320, DIS=2420). Patients treated with EIS were younger (69.95 years vs. 72.38 years, P<0.05) and had concomitant cardiogenic shock. Contrarily, prevalence of chronic kidney disease, heart failure, and pulmonary hypertension was higher in DIS group. EIS was associated with lower length of stay and total hospitalization cost. In-hospital mortality and pacemaker implantation rates were not significantly different between patients in the EIS and DIS groups.Conclusion: HDAVB is a rare complication of NSTEMI and often associated with right coronary artery disease. The timing of revascularization does not appear to influence the rate of pacemaker placement in NSTEMI complicated by HDAVB. Further studies are needed to assess if early invasive strategy can benefit all patients with NSTEMI and HDAVB.