Bidirectional ventricular tachycardia caused by occlusion myocardial infarction—a case report

Background: Bidirectional ventricular tachycardia (BdVT) is an uncommon form of ventricular arrhythmia typically associated with digoxin toxicity or catecholaminergic polymorphic ventricular tachycardia. BdVT in the setting of acute myocardial ischaemia is limited to case reports. We present an example of BdVT caused by occlusion myocardial infarction with original and modified Sgarbossa criteria being positive. Case summary: An elderly male with known coronary artery disease presented with chest pain. The initial ECG demonstrated a regular wide QRS complex tachycardia with alternating frontal plane axis, consistent with BdVT. No apparent cause of the arrhythmia was identified from the patient's medication history or family history. Detailed ECG analysis revealed that during tachycardia, the QRS complexes exhibited excessively discordant ST segment elevation and depression. ST segment concordance was observed in natively conducted beats of left bundle branch block morphology following termination of the arrhythmia. These findings raised suspicion of occlusion myocardial infarction as the direct cause of BdVT. This was subsequently confirmed by coronary angiography. Conclusion: BdVT is a distinct form of ventricular tachycardia, characterized by beat-to-beat alternation in QRS axis and morphology. BdVT in the context of acute ischaemia is rare and limited to case reports. Although this clinical presentation is exceptionally rare, in patients with BdVT and symptoms suggestive of acute coronary syndrome, active myocardial ischaemia should be considered as a potential underlying cause. This case highlights the utility of both the original and modified Sgarbossa criteria in identifying acute ischaemia in the setting of a wide complex rhythm.