Diffuse ST-Elevation Obscuring a Saddle Pulmonary Embolism: A Case of Misleading Electrocardiographic Finding

Document Type

Conference Proceeding

Publication Date

5-2026

Publication Title

American Journal of Respiratory and Critical Care Medicine

Abstract

Saddle pulmonary embolism (PE) is a life-threatening condition often presenting with syncope, dyspnea, chest pain, or hemodynamic instability. While electrocardiographic abnormalities may raise suspicion, diffuse ST-segment elevations are rarely associated with PE. We present a 61-year-old male with no prior medical history presenting after a syncopal episode. On EMS arrival, he was mildly hypoxic (SpO2 89% on room air) but hemodynamically stable. He denied chest pain, shortness of breath, or palpitations, though his symptom history was inconsistent. EKG on presentation showed diffuse ST-segment elevations, prompting urgent concern for acute coronary syndrome (ACS). Emergent left heart catheterization revealed only mild non-obstructive coronary artery disease and a myocardial bridge in the mid-LAD. He was subsequently treated for presumed pericarditis with colchicine and admitted in the cardiac care unit. A transthoracic echocardiogram performed the next day revealed severe right ventricular (RV) dilation, moderate to severe tricuspid regurgitation, RV systolic pressure estimated at 65-70 mmHg, and septal flattening, findings concerning for RV pressure overload. These findings prompted CT pulmonary angiography, which revealed a large saddle pulmonary embolism with an RV/LV ratio of 1.8 and extensive bilateral pulmonary emboli. Bilateral lower extremity DVTs were also identified. The patient underwent emergent thrombectomy by followed by IV heparin infusion for 48 hours. Hypercoagulable workup including antiphospholipid antibodies was negative. He was discharged on apixaban with plan to follow outpatient for malignancy screening. This case highlights how diffuse ST-segment elevations, although classically associated with pericarditis or transmural infarction, can mislead clinicians away from a diagnosis of PE. While rare, localized ST elevations, typically in right precordial leads have been reported in massive PE due to RV ischemia, but diffuse ST elevations are not typical. In this case, they served as a diagnostic distraction that delayed recognition of a life-threatening saddle embolism.The lack of classic PE features such as tachycardia, hypotension, or chest pain further complicated diagnosis. Early bedside POCUS or formal echocardiography could have revealed RV strain and prompted PE workup sooner.In patients presenting with syncope and diffuse ST elevations, clinicians must consider alternative diagnoses beyond ACS and pericarditis. This case illustrates how a misleading ECG and absence of classic PE features delayed recognition of a massive saddle PE. It illustrates the importance of maintaining a broad differential in syncope workups, especially when initial findings are atypical or discordant. Bedside echocardiography may serve as a critical tool in accelerating diagnosis and improving outcomes, especially in resource-limited or diagnostically ambiguous settings.

Volume

212

Issue

S1

First Page

S4229

Comments

American Thoracic Society International Conference, May 15-20, 2026, Orlando, FL

Last Page

S4229

DOI

10.1093/ajrccm/aamag162.5654

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