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[Reverse redistribution in the stress thallium scan--correlation of coronary blood flow and myocardial damage]
Insights
Reverse redistribution in stress thallium scans is more common after coronary revascularization procedures. This phenomenon suggests myocardial scarring with preserved blood flow to adjacent healthy tissue.
Area of Science:
- Cardiology
- Nuclear Cardiology
- Medical Imaging
Background:
- The 'reverse redistribution' (RR) phenomenon in stress thallium scans requires further elucidation, particularly in patients who have undergone revascularization.
- Investigating RR in patients with percutaneous coronary intervention (PTCA), coronary artery bypass graft (CABG), and no revascularization provides insights into myocardial viability and perfusion.
Observation:
- A study of 477 patients (74 PTCA, 86 CABG, 317 no revascularization) found RR occurred in 16% of PTCA, 13% of CABG, and 3.2% of non-revascularized patients.
- Reverse redistribution was significantly more prevalent in patients who had undergone PTCA or CABG compared to the control group (p < 0.01).
- Among patients with RR, those without significant coronary stenosis and with myocardial damage were more frequent (p < 0.01).
Findings:
- The incidence of RR was significantly higher in patients who had undergone PTCA or CABG (16% and 13%, respectively) compared to those without revascularization (3.2%).
- Patients exhibiting RR were more likely to have myocardial damage and less likely to have significant coronary artery stenosis.
- Quantitative analysis showed a trend towards higher washout rates in RR areas, though not statistically significant compared to normal values.
Implications:
- Reverse redistribution in stress thallium scans may indicate the presence of mixed myocardial tissue (scarred and viable) with adequate blood supply to the remaining healthy myocardium.
- The findings suggest that RR can be a marker for myocardial scarring coexisting with sufficient coronary blood flow, aiding in the assessment of myocardial viability post-revascularization.
- Understanding the mechanism of RR, involving initial thallium uptake in scarred areas and faster washout from adjacent normal myocardium, refines the interpretation of myocardial perfusion imaging.
Abstract:
In order to make clear 'reverse redistribution (RR)' phenomenon in stress thallium scan we investigated 477 consecutive patients who were consisted of 74 cases with PTCA (PTCA group), 86 cases with coronary artery bypass graft (CABG group) and 317 cases without any revascularization (N group). RR was detected in 12 cases out of PTCA group (16%), in 11 cases out of CABG group (13%) and in 10 cases out of N group (3.2%), and the incidence of RR in PTCA or CABG group was higher than that of N group (p less than 0.01). In 33 patients with RR the cases without significant coronary artery stenosis were more than those with stenosis (p less than 0.01) and the cases with myocardial damage were more than those without damage (p less than 0.01). In quantitative analysis washout rate at the RR areas showed relatively high value, but it was not significant compared with normal value (53 +/- 9.0% vs. 49 +/- 1.9%). In conclusion, RR had a tendency to appear in the condition of normal myocardium mingled with scar and of sufficient coronary blood flow. The mechanism of the phenomenon was thought to be that initial uptake of thallium in the partially scarred area was as high as in the normal myocardium, but washout of thallium from its remaining normal myocardium is normal or faster so that the defect appears at the myocardium mingled with scar. Therefore existence of reverse redistribution suspects the myocardium mingled with scar and sufficient coronary blood flow to the remaining normal myocardium.