TITLE:
From Infarction to Conduction Collapse: Complete Sino-Atrial Block Following Inferior ST-Elevation Myocardial Infarction: A Case from a Non-PCI Center
AUTHORS:
Christrian Ngongang Ouankou, Djibrilla Siddikatou, Mbua Larissa Kongnyuy, Archange Nzali, Michelle Ngono, Patrick Ateba, Yemele Honoré Kemnang, Ba Hamadou
KEYWORDS:
ST-Elevation Myocardial Infarction, Sino-Atrial Block, Temporary Cardiac Pacing, Thrombolysis
JOURNAL NAME:
World Journal of Cardiovascular Diseases,
Vol.16 No.5,
May
26,
2026
ABSTRACT: Background: ST-elevation myocardial infarction (STEMI) is frequently complicated by bradyarrhythmias, including sinoatrial block (SAB). The sinoatrial nodal artery, which supplies the sinoatrial (SA) node, originates from the right coronary artery (RCA) in approximately 60% of cases. Consequently, most cases of SA node dysfunction in the context of ischemia occur in inferior myocardial infarction (MI) and are potentially reversible. We report a case of inferior STEMI associated with a third-degree sino-atrial block. Case Report: A 61-year-old woman was admitted to the emergency department with a persistent epigastric burning sensation lasting 20 hours, followed by chest tightness for 2 hours prior to presentation, associated with dyspnea. Her cardiovascular risk factors included hypertension, hypercholesterolemia, and obesity. Emergency electrocardiography confirmed inferior and apicolateral STEMI complicated by a third-degree sinoatrial block with a junctional escape rhythm at 34 beats/min. Thrombolysis was performed, and the patient was subsequently referred for percutaneous coronary intervention (PCI). PCI was carried out 48 hours later with temporary cardiac pacing due to persistent conduction disturbances despite atropine therapy. Coronary angiography revealed significant stenosis of the RCA in its second segment, and thrombectomy successfully restored coronary blood flow. The temporary pacemaker was removed after monitoring showed stable sinus bradycardia at approximately 50beats/min. Follow-up ECG demonstrated significant regression of ST-segment elevation. Conclusion: Complete SAB in MI is less common than AV block but may be life-threatening. Prompt monitoring and early intervention are essential to prevent adverse outcomes. Thrombolysis, when indicated, should be considered in settings where PCI is not immediately available, with arrangements for timely and adequately equipped referral.