Reverse redistribution on thallium-201 single-photon emission tomography after primary angioplasty: a one-year follow-up study

Coronary arterial spasm during adenosine myocardial perfusion imaging

Adenosine is widely used as a pharmacologic agent for stress myocardial perfusion imaging. Vasospasm as a side effect of adenosine has been reported a few times in other countries, but it has not been reported in Japan. A 65-year-old woman was admitted to our hospital because of chest pain at rest and during exercise. She underwent myocardial scintigraphy, to rule out myocardial ischemia. After adenosine infusion, she felt chest pain and the electrocardiogram (ECG) showed ST elevation in inferior leads. Adenosine infusion was stopped immediately. Her chest pain resolved, and the ECG reverted to baseline. Perfusion image presented reverse redistribution in inferior segments, and coronary angiography revealed insignificant lesions. Transient ST elevation during adenosine infusion is thought to be due to coronary vasospasm, judging from scintigraphic and angiographic findings.

Coronary artery disease investigated using 99mTc-tetrofosmin myocardial SPECT

BACKGROUND

Coronary artery disease can be diagnosed from stress and delayed images of myocardial single photon emission computed tomography (SPECT) using technetium-99 m-tetrofosmin (TcTF). However, the negative predictive value of stress SPECT images after a single injection of a low tracer dose remains unknown. Thus, the present study investigates whether normal stress SPECT results predict event-free survival.

MATERIALS AND METHODS

We screened 302 consecutive patients who were randomly assigned to two groups for myocardial ischaemia using either stress SPECT with a low dose of TcTF (296 MBq, TcTF group, n = 150) or stress together with rest SPECT using thallium(201) chloride (TlCl, 111 MBq; TlCl group, n = 152) as the tracer. A total of 80 patients with abnormal SPECT findings were excluded and the remaining 222 with normal results (age, 66.5 +/- 0.7 years; TcTF/TlCl, 112/110) were enrolled in the present study and followed up for 401 +/- 9 days, with the endpoint being ischaemic cardiac events.

RESULTS

The incidence of cardiac events did not differ between the two groups (0.9% and 0.0% in TcTF and TlCl groups, respectively). The cost and duration of TcTF and TlCl SPECT examinations were about 425 and 603 Euros and 50 and 280 min, respectively.

CONCLUSIONS

The negative predictive values of stress SPECT using a low dose of TcTF and of combined stress and rest SPECT using TlCl did not differ and both were clinically acceptable. Thus, stress SPECT using low dose TcTF is useful in screening patients for myocardial ischaemia.

A reverse perfusion pattern during Technetium-99m stress myocardial perfusion imaging does not predict flow limiting coronary artery disease

BACKGROUND

A reverse redistribution pattern during myocardial perfusion imaging is most widely described using thallium (Tl-201), when stress images exhibit greater perfusion than rest. Technetium (Tc-99 m) radiopharmaceuticals may also yield a reverse perfusion (RP) pattern, but its significance is uncertain. This study tested the hypothesis that RP correlates with the presence and location of flow limiting coronary stenosis(es).

METHOD

We reviewed 842 consecutive Tc-99 m tetrofosmin SPECT stress studies performed at a cardiothoracic centre over a 15 month period. 69 (8.2%) demonstrated RP. Thirty-three patients (age 32-79 mean 56, 17 female) had undergone cardiac catheterisation within 12 months of the scan. Correlation was sought between the presence and location of angiographic stenoses and RP pattern.

RESULTS

10/33 (30.3%) had significant (>60%) coronary stenosis(es); 5 single-vessel, 2 two-vessel and 3 three-vessel disease (3VD). Stenosis location correlated poorly with the RP territory (LAD/Anterior 5/17, RCA/Inferior 1/10, Cx/lateral 0/4 (p = 0.57)). Of the 6 patients with a lesion in the RP territory, 3 had 3VD; 2 of these had a simultaneous reversible defect. All 5 patients with previous myocardial infarction had a simultaneous fixed defect. However only 3/12 with co-existent reversible defects had significant disease.

CONCLUSION

The reverse perfusion pattern is a poor predictor of flow limiting coronary disease, and does not correlate with stenosis location in those with significant lesions. Such patients should not undergo invasive investigation purely on the basis of this result.

High prevalence of (99m)tc-tetrofosmin reverse perfusion pattern in patients with myocardial infarction and angiographically smooth coronary arteries

BACKGROUND

There are no published data in the literature on the scintigraphic perfusion pattern in patients with myocardial infarction (MI) and normal coronary arteries (NCA).

OBJECTIVES

To evaluate myocardial perfusion imaging in a series of patients with MI and NCA.

METHODS

Twenty-seven patients who had developed a MI and had NCA were studied. As a control group we included 27 patients with a recent MI and coronary artery disease (CAD). All patients underwent stress/rest tetrofosmin myocardial perfusion SPECT within 6 months from MI.

RESULTS

In patients with NCA tetrofosmin stress images revealed 41 hypoperfused segments in 17 patients (63%). On rest images, 13 segments remained unchanged, 4 showed partial reperfusion, 10 normalized and 14 worsened. Additionally, there were 18 new hypoperfused segments in nine patients. Therefore, perfusion worsened at rest in 18 patients (67%) (32 segments). Overall, at rest there were 49 hypoperfused segments in 22 patients (81%). In patients with CAD, stress images revealed 71 hypoperfused segments. On rest images, 39 segments remained unchanged, 16 showed partial reperfusion and 12 normalized. Four segments worsened at rest and only four patients (15%) showed new perfusion defects at rest.

CONCLUSIONS

Myocardial perfusion with tetrofosmin might appear considerably worse at rest than at stress in patients with MI and NCA. Specifically, a reverse perfusion pattern in the infarct area is a frequent finding and is likely to be due to residual tissue viability. We postulate that in these patients the hyperemic response to exercise may mask resting underperfusion areas.

Detection of myocardial viability using rest-redistribution thallium-201 imaging in a stress 99Tcm-tetrofosmin/rest thallium-201 dual-isotope protocol

This study investigated the utility of optional thallium-201 (201Tl) imaging for detecting myocardial viability in the stress 99Tcm-tetrofosmin/rest 201Tl dual-isotope protocol. Seventy-nine patients with old myocardial infarction and 25 patients with acute myocardial infarction underwent acquisition of three consecutive 201Tl images (early, intermediate and delayed) using the dual-isotope protocol. A polar map was created and defect scores (extent and severity) were determined by comparison with normal control data. Fluorodeoxyglucose positron emission tomography was also performed in 16 patients with old myocardial infarction. In patients with old infarction, the severity score decreased significantly from the early to the intermediate images, and decreased further on the delayed images. In patients with acute infarction, the score increased from the early to the intermediate images, but not on the delayed images. Regional uptake on the delayed images showed a better correlation with the fluorodeoxyglucose images than that on the early images. Redistribution on the delayed images was exclusively observed in the myocardial segments with less uptake than that estimated by fluorodeoxyglucose. In conclusion, addition of delayed 201Tl imaging to the dual-isotope protocol could improve the sensitivity for detecting myocardial viability.

The clinical significance of reverse redistribution in Tl201 cardiac SPET

In an attempt to evaluate the clinical significance of reverse redistribution in Tl201 cardiac SPET, Tl201 SPET examinations included in the data base of our department have been retrospectively reviewed.

PATIENTS

Six hundred ninety eight patients demonstrated the pattern of reverse redistribution. For 237 of these patients' cardiac catheterization data were also available. One hundred and six patients of these had a history of myocardial infarction while the rest of them were referred for angina symptoms.

RESULTS

Catheterization showed that the infarction area was perfused by a stenosed but patent vessel in 79 of the 106 patients with a history of myocardial infarction (74.5%). Collateral circulation was evident in 21 of these 106 patients (19.8%). Only six patients (5.6%) showed a totally occluded vessel with no obvious evidence of collateral circulation. Of the 131 patients, with no myocardial infarction history, 14 (10.7%) had normal coronary vessels. The rest of the patients (89.3%) demonstrated stenotic vessels perfusing the same area where reverse redistribution was observed. Sixty-three of these patients have been reexamined after 9-36 months. On 15 of these patients (23.8%) the second scintigram showed ischemia in the same segments where reverse redistribution was initially detected. Another 17 of the above patients had a former scintigraphic examination that showed ischemia on the segments that currently demonstrated reverse redistribution.

CONCLUSION

The results of the present retrospective study indicate that, in patients with known coronary disease, the pattern of reverse redistribution frequently indicates the ischemic area.