Coronary microvascular dysfunction and myocardial area at risk assessed by cadmium zinc telluride single photon emission computed tomography after primary percutaneous coronary intervention in acute myocardial infarction patients

Abstract

Background: A high proportion of coronary microvascular dysfunction (CMD) has been observed in patients with acute myocardial infarction (AMI) who have received primary percutaneous coronary intervention (PCI), which may affect their prognosis. This study used cadmium zinc telluride (CZT) single photon emission computed tomography (SPECT) to evaluate the prevalence and characteristics of CMD and myocardial area at risk (AAR) in AMI patients who had undergone primary PCI.

Methods: We conducted a single-center cross-sectional retrospective study at TEDA International Cardiovascular Hospital from September 2021 to June 2022. A total of 83 patients received primary PCI for AMI. Subsequently, a rest/stress dynamic and routine gated myocardial perfusion imaging (MPI) were performed 1 week after PCI. The CMD group was defined as having a residual stenosis of infarct-related artery (IRA) <50% and myocardial flow reserve (MFR) <2.0 in this corresponding territory, whereas MFR ≥2.0 of IRA pertained to the normal control group. Rest-AAR of infarction (%) and stress-AAR (%) were expressed by the percentage of measured rest-defect-size and stress-defect-size in the left ventricular area, respectively. Logistic regression analyses were performed to identify significant predictors of CMD.

Results: A total of 53 patients with a mean age of 57.06±11.99 years were recruited, of whom 81.1% were ST-segment elevation myocardial infarction (STEMI). The proportion of patients with CMD was 79.2% (42/53). The time of pain to SPECT imaging was 7.50±1.27 days in the CMD group and 7.45±1.86 days among controls. CMD patients had a higher body mass index (BMI) than controls (26.48±3.26 vs. 24.36±2.73 kg/m², P=0.053), and a higher proportion of STEMI, thrombolysis in myocardial infarction (TIMI) 0 grade of IRA prior PCI than controls (88.1% vs. 54.5%, P=0.011; 61.9% vs. 18.2%, P=0.004, respectively). No significant difference was identified in the rest-myocardial blood flow (MBF) of IRA between the 2 groups, whereas the stress-MBF and MFR of IRA, rest-AAR, and stress-AAR in the CMD group were remarkably lowered. Higher BMI [odds ratio (OR): 1.332, 95% confidence interval (CI): 1.008-1.760, P=0.044] and stress-AAR (OR: 1.994, 95% CI: 1.122-3.543, P=0.019) were used as independent predictors of CMD occurrence.

Conclusions: The prevalence of CMD is high in AMI patients who received primary PCI. Each 1 kg/m² increase in BMI was associated with a 1.3-fold increase in CMD risk. A 5% increase in stress-AAR was associated with a nearly 2-fold increase in CMD risk. Increased BMI and stress-AAR predicts decreased coronary reserve function.

Keywords: Coronary microvascular dysfunction (CMD); acute myocardial infarction (AMI); myocardial flow reserve (MFR); percutaneous coronary intervention (PCI); single photon emission computed tomography (SPECT).

Figure 1

Inclusion flow chart. AMI, acute myocardial infarction; PCI, percutaneous coronary intervention; CABG, coronary artery bypass grafting; VT, ventricular tachycardia; AF, atrial fibrillation; AT, atrial tachycardia; CZT, cadmium zinc telluride; SPECT, single photon emission computed tomography; CAG, coronary angiography; MPI, myocardial perfusion imaging; MFR, myocardial flow reserve; CMD, coronary microvascular dysfunction.

Figure 2

A 65-year-old male patient with the chief complaint of persistent angina attack received primary PCI in TEDA International Cardiovascular Hospital. Left figures: coronary angiography showing complete occlusion of the LAD with no significant coronary stenosis and no significant spasm on left circumflex branch and right coronary artery. Central figure: routine adenosine stress plus rest serial tomographic images (row 1/3/5/7 for stress images, and row 2/4/6/8 for rest images) indicating a large perfusion defect in the anterior wall that is mostly reversible. Right figures: myocardial AAR at rest was 7%, Stress AAR 37%, showing that 30% area in the left ventricular area is reversible. Quantitative diagnosis with dynamic data is very definitive of the abnormal results and showed a significant reduction in MFR in the large LAD and a severe reduction in stress-MBF in the LAD (rest-MBF of LAD =0.90 mL/g/min; stress-MBF of LAD =1.11 mL/g/min; LAD-MFR =1.20), meeting the diagnostic criteria for CMD. SSS, summed stress score; SRS, summed rest score; SDS, summed difference score; SS%, summed stress%; SR%, summed rest%; SD%, summed difference%; MBFQ, myocardial blood flow quantitation; TPD, total perfusion defect; PCI, percutaneous coronary intervention; LAD, left anterior descending branch; AAR, area at risk; MFR, myocardial flow reserve; MBF, myocardial blood flow; CMD, coronary microvascular dysfunction.