Assessment of Residual Myocardial Viability Following Streptokinase Thrombolysis in ST-Segment Elevation Myocardial Infarction Using Nitrate-Enhanced Tc-99m Sestamibi SPECT: A Cross-Sectional Study

Abstract

Objectives: Nitrate-enhanced myocardial perfusion imaging using technetium-99m methoxy-isobutyl-isonitrile (Tc-99m MIBI) has been shown to improve detection of viable but dysfunctional myocardium. Aim of this study was to evaluate residual myocardial viability in patients with ST-segment elevation myocardial infarction (STEMI) after successful thrombolysis with streptokinase using nitrate-enhanced Tc-99m sestamibi single-photon emission computed tomography (SPECT). Methodology: This descriptive cross-sectional study was conducted at the Department of Cardiology and the Department of Nuclear Medicine and Molecular Imaging, Northwest General Hospital & Research Center, Peshawar. A total of 62 patients aged >16 years with STEMI who underwent successful thrombolysis with streptokinase were included. Myocardial viability was assessed using a one-day nitrate-enhanced Tc-99m sestamibi SPECT protocol. Viability was defined as ≥50% tracer uptake in affected myocardial segments. Results: The mean age of participants was 53.8 ± 12.9 years, with a predominance of males (80.64%). Mean myocardial viability was 66.9 ± 29.17% in the left anterior descending (LAD) territory, 88.9 ± 14.87% in the left circumflex (LCX) territory, and 76.6 ± 30.99% in the right coronary artery (RCA) territory. When stratified by infarct location, anterior wall MI showed LAD viability of 61.4 ± 27.92%, lateral wall MI showed LCX viability of 75.6 ± 12.5%, and inferior wall MI showed comparatively lower RCA viability of 41.6 ± 32.08%. Conclusion: Nitrate-enhanced Tc-99m sestamibi SPECT imaging demonstrated substantial residual myocardial viability in patients with STEMI following successful streptokinase thrombolysis. These findings highlight its clinical utility in resource-limited settings for identifying viable myocardium and guiding subsequent management decisions.