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Reverse redistribution of thallium-201 myocardial single photon emission tomography and contractile reserve
K Hirata1, H Yamagishi, T Tani
1First Department of Internal Medicine, Osaka City University Medical School, Japan.
Insights
Myocardium showing reverse redistribution (RRD) on thallium-201 SPECT after heart attack has better contractile reserve. This reserve is greater compared to myocardium with fixed defects, indicating improved function with dobutamine stress.
Area of Science:
- Cardiology
- Nuclear Cardiology
- Cardiac Imaging
Background:
- Assessing myocardial contractile reserve post-acute myocardial infarction (AMI) is crucial for prognosis.
- Thallium-201 (201Tl) SPECT is used to evaluate myocardial perfusion and viability.
- Reverse redistribution (RRD) on 201Tl SPECT suggests potential for functional recovery.
Purpose of the Study:
- To investigate the contractile reserve of myocardium exhibiting RRD on 201Tl SPECT after AMI.
- To compare contractile reserve in RRD versus fixed defect (FIX) patterns.
- To correlate the extent of RRD with functional improvement under stress.
Main Methods:
- Forty patients with first AMI underwent resting 201Tl SPECT and low-dose dobutamine stress echocardiography (DSE) within 4 weeks.
- Left ventricle segmented into 13 regions for analysis of SPECT defects and DSE wall motion abnormalities.
- Total defect score (TDS) and total wall motion score (TWM) calculated; quantitative 201Tl uptake assessed.
Main Results:
- RRD observed in 16 patients, FIX in 23.
- Significant improvement in TWM from rest to stress in both RRD and FIX groups (p<0.0001).
- Dobutamine-induced TWM improvement was significantly greater in the RRD group (1.6±1.0) compared to the FIX group (0.6±0.7) (p=0.001).
- Positive correlation found between RRD magnitude and TWM improvement with dobutamine (r=0.48, p=0.002).
Conclusions:
- Myocardium with RRD on 201Tl SPECT demonstrates greater contractile reserve post-AMI compared to myocardium with FIX.
- RRD on 201Tl SPECT is a marker of preserved or recoverable myocardial function.
- Dobutamine stress echocardiography effectively unmasks enhanced contractile reserve in RRD segments.
Abstract:
The present study investigated the contractile reserve of myocardium exhibiting reverse redistribution (RRD) of thallium-201 (201Tl) after acute myocardial infarction. Forty patients experiencing their first acute myocardial infarction underwent resting 201Tl single-photon emission computed tomography (SPECT) and low-dose (5-10 microgxkg(-1)xmin(-1)) dobutamine stress echocardiography (DSE) within 4 weeks after the onset of infarction. The left ventricle was divided into 13 segments for analysis. The severity of defects in 201Tl SPECT and the extent of wall motion abnormality in DSE were visually assessed and scored. The sum of each defect score and wall motion score of infarct-related segments were defined as total defect score (TDS) and total wall motion score (TWM), respectively. Quantitative analysis of 201Tl uptake was also performed. Resting 201Tl SPECT revealed RRD in 16 patients (group RRD), fixed defect (FIX) in 23 patients (group FIX), and redistribution in one. There was a significant difference in improvement of TWM between rest and stress in TWM in both the RRD and FIX groups (p<0.0001, each case). The improvement of TWM with dobutamine was significantly greater in RRD than in FIX (1.6+/-1.0 vs 0.6+/-0.7, p=0.001). There was a positive correlation between the magnitude of RRD and improvement of TWM with dobutamine (r=0.48, p=0.002). Myocardium exhibiting RRD on 201Tl SPECT in patients with acute myocardial infarction has greater contractile reserve than that exhibiting a fixed defect.