Title : A Case of Delayed Contrast Anaphylaxis Leading to ST-Elevation Myocardial Infarction (STEMI)
Abstract:
Case: Patient is an otherwise healthy 69 year old male with inferior STEMI s/p proximal RCA stent 3 days prior who was discharged in stable condition. Patient had been discharged on aspirin and clopidogrel for dual antiplatelet therapy. 48 hours after discharge, and a total 72 hours after initial angiogram, he noted to have hives on his chest wall and abdomen with trouble breathing at home. He sought medical attention again. He was noted to have ST-T wave elevation in the anteroseptal leads concerning for anterior MI (see Figure A). During this time, he also became hypotensive. He was given anaphylactic regimen due to presumed allergic reaction, and subsequently the anteroseptal lead changes resolved with new findings in the inferior leads (see Figure B). This was an inconsistent presentation of STEMI within two separate territories. Decision was made to transfer patient urgently to our facility for higher level of care. In the meantime, he was treated with benadryl, steroids, and fluids for anaphylactic shock. His echocardiogram showed left ventricular function of 55% with mild inferior wall hypokinesis, otherwise no significant valvular disease.
Upon arrival to our facility, patient was urgently taken to catheterization lab again. The left coronary system was engaged first which did not show any new findings from angiogram 3 days prior. Therefore, we proceeded to the right coronary system which was found to have acute thrombosis of the previously placed proximal RCA stent. Balloon angioplasty was performed with subsequent aspiration thrombectomy with immediate restoration of flow in the right coronary system. Patient had an uneventful postoperative course and was continued on benadryl until day of discharge. He was able to discharge to home in stable condition. He was discharged on aspirin and ticagrelor for dual antiplatelet therapy.
Conclusion: It is known from prior literature that anaphylaxis can trigger a pro-thrombotic state as it can acutely affect platelet numbers and function. In the case of our patient, it is hypothesized that delayed contrast reaction caused anaphylaxis which ultimately led to thrombosis in a newly deployed stent. Further research can be helpful clinically to determine management or screening recommendations in at risk patients.
