A 41-year-old man received an electrophysiological study (EPS) and radiofrequency catheter ablation (RFCA) for atrioventricular reentrant tachycardia (AVRT) in our hospital. Massive pulmonary embolism (PE) with hypotension developed 9 hours after these procedures. After emergent pulmonary angiography and catheter-directed intrathrombus urokinase infusion and clot breaking, the patient recovered well. This case suggests that life-threatening PE may occur in patients who receive EPS, RFCA, or both. An adequate observation time after RFCA and clinical alertness are necessary for immediate diagnosis and treatment. Emergent catheter-directed therapy may be of benefit in some patients with acute massive PE.