Complete heart block: A rare complication in anterior wall MI

M. Deepak, S. Aravindakumar

Cardiology Resident, Department of cardiology, Kauvery Hospital, Heart city, Trichy

Chief Consultant Interventional Cardiologist, Kauvery Hospital, Heart city, Trichy

Case Presentation

A 41-years-old male known type 2 diabetes mellitus presented with chest pain and ECG suggestive of evolved anterior wall MI. Though it was a late presentation, primary PCI to LAD was done in view of persistent chest pain and cardiogenic shock. Post PTCA ECG showed mild type 1 AV BLOCK.

The patient developed complete heart block the next day. Check CAG was done which showed patent stent

The most probable cause for complete heart block would be late presentation leading decreased perfusion to infranodal his bundle conducting system due occlusion of septal branches. There was need for temporary pacing, the patient showed remarkable improvement, with no requirement for a permanent pacemaker at discharge.

Discussion

Blood supply of conducting system

Complete heart block (CHB), a serious AMI complication, is crucial for prognosis but uncommon, with an incidence of 2.3 % [1]. CHB is more prevalent in inferior AMI (9.4 %) compared to anterior AMI (2.5 %) [2] and is associated with higher in-hospital and all-cause mortality, particularly in anterior infarctions [3]. It predominantly affects older females with comorbidities [1,4].

In anterior ST-elevation myocardial infarction (STEMI), CHB usually arises from infranodal His-Purkinje system lesions due to septal perfusion disruption. Septal perforator branches of the left anterior descending (LAD) supply the anterior two thirds of the interventricular septum as well as the bundle of His [6]. This leads to escape rhythms, characterized by wide QRS complexes, with a mean onset of 16.6 hours from the chest pain onset [7]. The development of a new bundle branch at this lesion is indicative of significant myocardial damage and associated with high Killip class on admission, poorer left ventricular function, and acute mortality [7,8].

Conclusion

In our presented case, the patient’s need for temporary pacing due to complete heart block resolved without necessitating a permanent pacemaker. This favors reversible ischemia rather than extensive necrosis of the proximal conduction system since the conduction system being relatively resistant to ischemia [8,9]. This underscores the importance of rapid identification and vigilant monitoring by physicians. CHB in anterior STEMI patients is associated with poorer outcomes and may need permanent pacemaker, despite advances in early diagnosis and reperfusion therapy.

Reference

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