S1Q3T3 Pattern in Lemierre Syndrome: Acute Cor Pulmonale Masquerading as Massive Pulmonary Embolism

Lemierre syndrome involves internal jugular vein thrombophlebitis and metastatic septic emboli. This pathology can hemodynamically mimic massive pulmonary embolism.

A 27-year-old man with sepsis and tachycardia (heart rate: 156 beats/min) exhibited an S1Q3T3 electrocardiographic pattern. Computed tomography angiography ruled out central pulmonary embolism but revealed septic emboli and internal jugular vein thrombus. Therapeutic anticoagulation was started for presumed deep vein thrombosis, then was held upon confirming Fusobacterium necrophorum bacteremia to minimize bleeding risk, then was resumed (rivaroxaban) at 4 weeks for persistent occlusion.

This case illustrates acute cor pulmonale and S1Q3T3 pattern without central obstruction. Diffuse septic microemboli and inflammatory vasoconstriction likely generated sufficient pulmonary vascular impedance, resulting in right ventricular strain.

The S1Q3T3 pattern can occur in Lemierre syndrome owing to diffuse microvascular occlusion, even when computed tomography angiography is negative for central thrombus. Identification of septic thrombophlebitis requires thorough cardiovascular examination and integration of bedside point-of-care ultrasound with an evidence-based anticoagulation strategy.