High-grade atrioventricular block in acute coronary syndrome: Portuguese experience
Introduction
Ischaemic heart disease is a major health problem, responsible for 20% of worldwide deaths, a fraction of them in the context of acute coronary syndrome (ACS) [1]. During the ACS, myocardial injury and ischemia can produce conduction disturbancesSome patients develop severe manifestations of conduction disorders like high-grade atrioventricular block (HAVB). HAVB in ACS had a reported incidence of 3–14% and is associated with increased in-hospital mortality [2,3].
Considering the ischemia transient effects, even in cases that required temporary pacing, a waiting period is recommended to understand if an indication for a permanent pacemaker remains [4]. For this reason, revascularization should always be considered in patients with HAVB who did not receive reperfusion therapy initially [1]. Nevertheless, the large series dedicated to HAVB in the setting of ACS were performed before the massive use of primary percutaneous coronary intervention as reperfusion therapy in ACS.
The short and long-term impact of HAVB in the setting of ACS is not completely clear. Yet, it seems to be directly related to the myocardial injury extension and the intraventricular conduction disturbance caused by ischemia [4].
Section snippets
Objectives
The main goal of this study was to analyse the rate, clinical features, therapeutic approach, complications, in-hospital mortality and follow-up of HAVB in the setting of ACS in a real-world scenario using data from the Portuguese Registry of Acute Coronary Syndromes.
Pro-ACS registry design
The Portuguese Registry of Acute Coronary Syndromes (Pro-ACS - ClinicalTrials.gov NCT 0162329) is a continuous, nationwide, prospective, observational registry launched in 2002. Data is uploaded by participating centers and managed by the Portuguese Society of Cardiology. All ACS patients older than 18 years are eligible for inclusion. ACS episodes (including unstable angina, non-ST segment elevation myocardial infarction (NSTEMI) and ST segment elevation myocardial infarction (STEMI)) are
Population clinical features
A total of 626 (2.6%) patients were categorized as having a HAVB in the setting of ACS, 487 patients in the STEMI group, 139 patients in the NSTEMI group and any patients in the unstable angina group. Patients with HAVB were older, more frequently females and had a higher prevalence of comorbidities, namely stroke history (p < 0.001) and neoplasia (p = 0.031). On the other hand, cardiovascular conditions were more frequent in patients without HAVB, especially dyslipidaemia and history of
Discussion
The identification in our population of HAVB in the setting of ACS confirmed the worse prognosis of this group during hospitalization. The prevalence of HAVB in our study was lower compared with previously reported series [3,7,8]. This may be explained by the fact that the majority of the series about this theme were published before the primary revascularization with PCI was routinely performed and the inclusion of NSTEMI patients that have a lower risk of HAVB development.
Initial analysis
Limitations
There are several limitations to be considered in the study interpretation. This was observational and non-randomized study, which can have associated confounders that can influence the outcomes. All registers have a risk that some of the patients could have misclassified characteristics, incomplete records and under-reporting complications like HAVB. Analysis of differences between patients with and without the combined endpoint was performed with univariable, non-adjusted models without
Conclusion
Our results are in line with several publications that suggested HAVB is a major complication of ACS with a significant impact on prognosis. HAVB should require special attention since its occurrence influences MACE and in-hospital mortality. Further investigation should focus on the determination of the influence of multivessel disease in the occurrence of HAVB in the setting of ACS. Despite the contradictory results of different series, it seems that HAVB in the setting of ACS is associated
Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Declaration of competing interest
The authors declare that there is no conflict of interest.
Acknowledgments
The authors would like to thank the Portuguese National Center for Data Collection in Cardiology and the Portuguese Society of Cardiology and Adriana Belo for statistical support and data management.
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