Regadenoson-Induced ST Elevation: Unmasking Extensive CAD!

The above images demonstrate the markedly abnormal electrocardiographic response to Regadenoson (vasodilator) stress test (Figure A) performed for atypical chest discomfort, and the subsequent angiography results (Figures B & C). Figure A represents the summary of the electrocardiogram (ECG) part of the regadenoson stress Sestamibi test. Significant, > 2 mm, ST-segment elevation is noted in lead aVR with nearly reciprocal ST-segment depression in leads I & aVL (blue arrows) indicative of severe subendocardial ischemia often associated with extensive multivessel or left main (LM) coronary artery disease (CAD). More notable, however, is the ST-segment elevations in the inferior leads, especially lead III and aVF, (black arrows) with ST-segment depression in leads V2 and V3 (green arrows), highly concerning for transmural inferoposterior ischemia. This resolved within few minutes of stopping the Regadenoson and did not cause troponin level elevation. Cardiac catheterization in the anteroposterior (AP) cranial view (Figure B) revealed LM (red arrow) with a critical 99% stenosis. The left anterior descending (LAD; orange arrows) showed 95% proximal stenosis (at the origin of a diagonal) and poor filling distal (TIMI I flow) due to underfilling from the critical LM disease. Ostial and proximal first diagonal (D1; yellow arrows) revealed 80% stenosis. The left circumflex (Cx) is shown in blue arrows underfilling due to critical LM disease. The first obtuse marginal (OM1) and ramus intermedius (RI) had moderate 40 - 50% stenoses. Figure C is a left anterior oblique (LAO) straight angiographic view of the right coronary artery (RCA) revealing moderate 50% proximal and mid, and 80% distal stenoses (brown arrows). The posterior left ventricular branch (PLVB; purple arrow) had 80% stenosis. The extent of the disease necessitated intra-aortic balloon bump (IABP) insertion followed by prompt coronary artery bypass grafting (CABG) with adequate post-operative recovery.