Myocardial Perfusion Spect Findings In Postcovid Period

Purpose: To investigate if i) the risk of ischemia on Myocardial Perfusion Scan (MPS) ii) number of coronary angiographies (CAG) performed iii) necessity for invasive (stent implantation or coronary artery by-pass grefting (CABG)) or medical treatment increased in patients infected with COVID-19.Methods:Patients who were referred to MPS between August 2020-April 2021 with a history of active symptomatic Covid-19 infection (confirmed by PCR positivity) in the last 6 months were involved in the study group. Age-and gender matched control group was composed of randomly chosen patients who attended for MPS between January 2019 – September 2019, before pandemic. Frequency of ischemia, CAG, invasive or medical treatments were compared between groups. Results:Ischemia was reported more frequently in the study group (p<0.001). In clinical evaluation, regardless of the MPS results, the necessity for invasive evaluation with CAG and treatment (either medical therapy or invasive interventions), was higher in the study group (p=0.006 and p=0.015). It was also true for patients with abnormal MPS results (p=0.008 and p=0.024) but not for the patients with ischemia (p=0.29 and p=0.06).Conclusion:There exists a significant increase in the frequency of ischemia on MPS, undergoing CAG, stent implantation or CABG and initiation of medical therapy in patients with a history of Covid-19 infection in the last 6 months. MPS is a reliable method in patients who present with cardiovascular symptoms in the late COVID period.

Changes in ventricular depolarisation vectors during exercise caused by regional myocardial ischaemia

Research at the Aga Khan University for several years has been directed to find a reliable, low-cost, portable, non-invasive method for identification of coronary artery disease, its location and extent. A new method has been devised to measure the magnitude and direction of cardiac electrical vectors in three perpendicular planes during physical exercise to identify reduction in myocardial excitability as the electrophysiological marker of hypoxia. This report shows that changes in electrical forces due to exercise-induced regional hypoxia serve as indicators of reversible myocardial ischaemia. Changes in the magnitude and direction of vectors at stages of the Bruce protocol were measured in healthy volunteers, and patients undergoing the same exercise protocol for distribution of a radioactive tracer injected intravenously at peak exercise and after recovery (myocardial perfusion scan). Alterations in the magnitude and direction of resultant vectors during exercise were scored to enable analysis. Analysis identified slow progression of myocardial depolarisation as the electrophysiological marker of regional hypoxia relative to physical work. Compared with myocardial perfusion scan the sensitivity and specificity of electrical vectors for identification of ischaemia were 88% and 71%, respectively. Accuracy of ischaemia shown by electrical vectors is being assessed in patients undergoing elective coronary angiography.