Abstract 13331: Case Report Of Transient Right Bundle Branch Block With S1q3t3 Pattern In Acute Pulmonary Embolism

Abstract

69 year old woman with hypertension, sleep apnea and who had a recent knee replacement, was brought in to the emergency room (ER) for syncope. She had her physiotherapy session earlier in the day and became symptomatic with dizziness and shortness of breath and passed out. In the ER she had a systolic blood pressure (SBP) of 90mmHg and an oxygen saturation (O2 sat) of 80% on room air. She was given fluid bolus with improvement of SBP to 110mmHg. O2 sat improved to 99% with 10L of oxygen. Treatment was started with full dose of Enoxaparin subcutaneously. A 12-lead electrocardiogram (EKG) showed sinus tachycardia (ST) at 117 beats per minute (BPM), right bundle branch block (RBBB) and S1Q3T3 pattern. A bedside echocardiogram showed right ventricular (RV) distension. A CT-angiogram showed bilateral main stem pulmonary emboli (PE) with signs of RV strain. Patient was admitted and remained hemodynamically stable. A repeat EKG done the following day showed ST at 110 BPM with resolution of RBBB. An echocardiogram done now showed normal RV size and function. Patent was eventually discharged home on full dose apixaban. Q3S1T3 Figure 1 - ST, RBBB, S1Q3T3 pattern Figure 2 - ST Discussion: The patient presented with new RBBB (Figure 1) due to RV strain from acute PE as shown by the CT-angiogram and bedside echocardiogram. The EKG also showed S1Q3T3 pattern. With the resolution of the RV strain the following day, as noted on the subsequent echocardiogram, the 12 lead EKG showed the resolution of the RBBB and the QRS complex became narrow (Figure 2). RBBB is thought to be caused by acute RV overload and dilatation, accompanied by subendocardial ischemia in the right bundle. The S1Q3T3 pattern is historically considered as a “classic” EKG pattern associated with acute PE, even though it is neither sensitive nor specific for acute PE. Conclusion: The RBBB along with the S1Q3T3 pattern and its resolution with improvement of RV hemodynamics, is the first reported case in the literature.