Utilising pyrophosphate uptake imaging to establish the timing of acute myocardial infarction: An often-forgotten art.

ABSTRACT

INTRODUCTION: While pyrophosphate uptake imaging with Technetium-99 m pyrophosphate (Tc-99 m PYP) is frequently used for cardiac ATTR amyloid imaging, its role in determining the timing of acute myocardial infarction (AMI) is near forgotten. We present a case that demonstrates the clinical benefit of pyrophosphate uptake imaging in differentiating recent from remote infarction as a reminder of the continued utility of pyrophosphate uptake imaging for this indication. CASE AND OUTCOMES: A 68-year-old male was referred for surgical replacement of his bicuspid aortic valve with severe aortic regurgitation. He was clinically well, but an elective pre-operative electrocardiogram suggested an anteroseptal wall infarct of possibly recent onset. Troponin-I was elevated at 430 ng/L (N < 26 ng/L) but did not change significantly over several days. Coronary angiography confirmed an occluded left anterior descending artery. Tc-99 m PYP uptake imaging was then utilised to determine the age of infarct and demonstrated mild regional tracer uptake in the left ventricular apex, consistent with a recent infarction. As the infarct was recent, elective surgery was postponed. DISCUSSION: In this case, the age of the patient's AMI had an important bearing on the timing of his elective surgical aortic valve replacement. Given the recommendation to delay elective cardiac surgery in patients with recent myocardial infarction to reduce peri­operative morbidity and mortality, this now rare use of pyrophosphate uptake imaging was critical in helping determine when cardiac surgery could be performed safely. CONCLUSION: This case demonstrates the clinical utility of pyrophosphate uptake imaging in establishing the temporal profile of myocardial infarction to help guide appropriate clinical management.