Despite the nearly two-year span since the emergence of the COVID-19 pandemic and the widespread use of vaccines globally, COVID-19 remains a significant contributor to mortality. Cardiovascular complications, including acute myocardial infarction (AMI), myocardial injury, arrhythmias, and thrombotic events, may also contribute to the morbidity and mortality of affected patients (8). Myocardial perfusion imaging (MPI) is a non-invasive imaging modality employed for the diagnosis and assessment of coronary artery disease (9). However, the COVID-19 pandemic has raised concerns regarding the potential implications of COVID-19 on the outcomes of MPI assessments. To our knowledge, this is the first study evaluating the effect of COVID-19 on myocardial perfusion imaging in Iran.
This research involved the referral of 750 patients for myocardial perfusion scans by cardiologists. A total of 328 patients (47.73%) tested positive for COVID-19. There was a higher rate of referrals among patients who had comorbid conditions such as hypertension, diabetes, and obesity. Specifically, obese COVID-19-positive patients were found to have a significantly higher rate of referral and abnormal MPI. In a study by Chan-Young Jung et al. (2021), higher BMI levels were associated with a graded susceptibility to severe COVID-19 infections (10). Additionally, Bolukcu et al. found that the mean BMI level of deceased COVID-19-positive patients was 31 kg/m2 and that there was no significant difference (P = 0.09) compared to COVID-19-negative patients However, the BMI of patients requiring intensive care was significantly higher (P = 0.04) in the COVID-19 group (11). Peters et al (2021) demonstrated that a higher BMI, waist circumference, waist-to‐hip ratio and waist‐to‐height ratio were each associated with an increased risk of death from COVID‐19, influenza/pneumonia and coronary heart disease (12).
In addition to mild to severe complications during the acute phase, COVID-19 symptoms may persist even after complete recovery, a condition known as "long COVID-19 syndrome". This phenomenon is believed to be the result of immune system dysregulation, autoimmune reactions, and viral persistence. The most commonly reported symptoms of long COVID-19 include fatigue and dyspnea, which can last for months after the initial COVID-19 infection. Other symptoms may include cognitive and mental impairments, chest and joint pains, palpitations, myalgia, anosmia and ageusia, cough, headache, and gastrointestinal and cardiac issues. In a retrospective cohort study conducted by Wong et al (2022), COVID-19 survivors had a higher risk of cerebrovascular and cardiac complications including stroke, arrhythmia, myocarditis, ischemic heart disease, heart failure, and thromboembolic disorders. Additionally, the probability of survival in COVID-19 survivors decreased significantly in all cardiovascular outcomes (13). In the present study, chest pain and dyspnea were found to be the primary reasons for referral, while other indications such as screening and evaluation of surgical candidates due to their non-emergent nature were the least common causes of referral. The persistence of long COVID-19 symptoms underscores the need for continued monitoring and management of patients after the acute phase of the illness has passed. Further research is needed to better understand the underlying mechanisms of this condition and to develop effective treatments.
The findings of our study demonstrate a lack of statistically significant association between abnormal perfusion imaging and COVID-19. It is plausible that this result is attributable to the exclusion of a substantial number of patients who may have exhibited abnormal myocardial perfusion imaging. There has been considerable apprehension regarding seeking medical assistance in healthcare facilities since the onset of the COVID-19 pandemic, leading to delayed detection and treatment of medical conditions. Nappi et al (2020) investigated the impact of COVID-19 on SPECT-MPI in a single center study in italy, similar to our experience they also found no significant difference between infected and non-infected patient, claiming that 68% of patients were missed based on the fact that the MPI rate has declined in comparison to the prior years(14) In our center, the number of patients referred for MPI scans did not exhibit a significant decrease. However, there was a change in patient referral indications, with a shift from non-emergency cases to those presenting with chest pain and dyspnea secondary to COVID-19. Our findings are supported by Hasnie et al.'s (2020) validation that COVID-19 does not adversely affect MPI, but the study also reported a high rate of missed abnormal patients at 81% during the study period (15).
While most diagnostic parameters of the MPI scan did not exhibit significant differences between the two groups, the visualization of right ventricle was observed more frequently in COVID-19 positive patients. This finding may be attributed to the possibility of pulmonary hypertension secondary to COVID-19 pathology. Furthermore, the COVID-positive group exhibited significantly higher rates of obesity and familial history of heart disease, which may be due to physician caution and/or increased prevalence of post-COVID syndrome.
In terms of MPI abnormalities, there was only a slight increase in mild and moderate ischemia in COVID-positive patients, while severe ischemia and myocardial necrosis did not differ significantly between the two groups. However, the presence of more hypokinesia could be indicative of endothelial dysfunction.One of the significant limitations of our study pertains to its single-center, retrospective design and relatively small sample size, which restricts the generalizability of our findings. Additionally, the inclusion of patients in the study using varied diagnostic methods, notwithstanding PCR being the standard diagnostic approach, introduces a potential for misdiagnosis of COVID-19 negative patients. The heterogeneity in the severity of COVID-19 among diagnosed patients and the interval (less than six month) between COVID diagnosis and myocardial perfusion imaging further challenges the interpretability of our results. Attempts were made to contact enrolled patients to address this issue; however, a vast majority of patients expressed apprehension, resulting in neglect of this matter. Due to feasibility, the control group utilized in the study was of a historical nature rather than being concurrent without having any restrictions imposed on the use of MPI.