S1Q3T3 Leading to Early Suspicion of Pulmonary Embolism in Low-Risk Patient

Background/Abstract: Acute pulmonary embolism (PE) may prove fatal without early suspicion and subsequent treatment. Many cases go undiagnosed, with one study showing an estimated 70% of post mortem PE cases were undiagnosed at the time of death.1 Young patients are most at risk of being misdiagnosed as suspicion in this population is very low. Even with a variety of diagnostic modalities a high clinical suspicion remains key for diagnosis.2 The varying degree of clinical presentation makes diagnosing PE very difficult. Here we present a case of a patient with no known risk factors and WELLS score of 0 whose electrocardiogram (EKG) findings led to an early investigation, diagnosis, and subsequent treatment of a massive pulmonary embolism. Case Report: A 34 year old AAM with a PMHx of asthma presented to our ED with a chief complaint of substernal chest pain with associated dyspnea. On arrival, the patient was hemodynamically stable with all VS in normal range. CXR showed no acute process. Our team was called to admit the patient from the ED for uptrending troponins and an EKG with inferior lead T-wave inversions. Troponins trended up to 0.255. His EKG showed sinus tachycardia with T-wave inversion in inferior and anterior leads along with S wave in lead I and Q wave in lead III. WELLS score was 0. Though not sensitive, the EKG findings increased our suspicion for PE. D-dimer was ordered and found to be elevated at 6,693. A stat Chest CTA revealed a large saddle pulmonary emboli. LMWH therapy was initiated. Work-up for genetic and acquired factors were negative and patient was discharged on oral anticoagulation. Discussion/Conclusion: EKG findings in patients with PE have been a topic of much debate since first reports of investigation in 1935. Over the years medicine has evolved with ubiquitous access to more effective modalities for diagnosing PE. Despite the advent of these other modalities, the diagnosis of PE remains elusive and the prognosis is variable depending on clinical presentation and appropriate diagnosis and treatment.4 While the S1Q3T3 pattern is commonly taught in medical schools around the world as the pathognomonic ECG pattern associated with pulmonary embolism, its reported incidence in acute PE is highly variable with studies showing its incidence anywhere from 10-50%.5 Non-specific ST elevation and T wave inversion in inferior and anterior precordial leads are the most frequently noted EKG abnormalities in patients presenting with acute PE.6 Acute pulmonary embolism in young males without risk factors is rare. Given the time sensitive nature of appropriate diagnosis and treatment of PE, it is important that health care providers recognize EKG findings characteristic of PE. These findings can incite suspicion in low risk patients and direct subsequent work-up and management in a timely fashion.