Background: Supraventricular tachycardia (SVT) is a common cardiac dysrhythmia originating from the atria, characterised by a narrow QRS complex (<120 ms) and a ventricular rate >100 bpm on ECG. While SVT can be an independent entity, it can also result from various triggers such as structural heart disease, thyroid abnormalities, electrolyte imbalances, infection, caffeine, and alcohol excess. This case report highlights
pulmonary embolism (PE) as a rare yet significant cause of SVT. Early recognition and treatment of PE in such clinical scenarios are essential for preventing complications and improving outcomes.

Case Presentation: We describe a 53-year-old male brought in by ambulance to the emergency department with a heart rate of 200 beats per minute, palpitations, and chest tightness. Despite attempts with vagal manoeuvres and AV node-blocking medications, SVT persisted. Considering the patient’s limited mobility from a bilateral knee replacement and recent long-haul flight, a decision was made to perform a CT pulmonary angiography (CTPA) that confirmed the presence of bilateral small pulmonary emboli.

Discussion: PE as a cause of SVT is uncommon but crucial to consider in the evaluation of persistent tachycardia. This case emphasizes the need for a high index of suspicion and thorough investigation, especially when common treatments show limited efficacy. Recognition and management of PE are pivotal in preventing complications and mortality.

Conclusion: This case study aims to raise awareness of the potential association between pulmonary embolism and persistent supraventricular tachycardia. Clinicians should remain vigilant in recognizing this rare but critical connection, especially when conventional treatments prove inadequate. Early diagnosis and intervention for pulmonary embolism can significantly impact patient outcomes.