A prospective study on the impact of high-grade atrioventricular block (HAVB) on outcomes in patients with acute myocardial infarction (AMI).

Background: Contemporary data on the impact of high-grade atrioventricular blocks (HAVB) in acute myocardial infarction (AMI) are scarce. Therefore, we investigated this in the Swiss national AMI registry (AMIS Plus) cohort.

Methods: We included all AMI patients enrolled from January 2005 to September 2024 with available ECG information. Primary outcome was in-hospital mortality; secondary outcomes included in-hospital major adverse cardiac or cerebrovascular events (MACCE) defined as cardiogenic shock, stroke, re-infarction or death.

Results: Among 50'279 AMI patients, 747 (1.5%) patients presented with HAVB and 407 (0.8%) developed HAVB during hospitalisation. Patients presenting with HAVB had increased in-hospital mortality (15% vs. 4.9%; p<0.001) and MACCE (17% vs. 6.0%; p<0.001) compared with those without HAVB. HAVB on admission was an independent predictor for in-hospital mortality (OR 1.89;95% CI, 1.42-2.49; p<0.001), with a stronger impact on mortality in the setting of anterior compared to non-anterior AMI (OR 3.69; 95% CI, 1.99-6.81; pinteraction=0.02). Independent predictors for HAVB on admission included STEMI and female sex. Rates of permanent pacemaker implantation during hospitalisation in patients with HAVB on admission were higher in NSTEMI than STEMI patients (20% vs. 4.4%; p< 0.001). HAVB occurring during hospital stay was associated with higher mortality (20% vs. 15%; p=0.031) and higher permanent pacemaker rate (25% vs. 8%; p< 0.001) than HAVB on admission.

Conclusion: HAVB in AMI was associated with high in-hospital mortality, especially in anterior AMI or if occurring during hospitalisation. Permanent pacemaker implantation was more frequent in the setting of NSTEMI and among patients developing HAVB during hospital stay.