Myocardial thallium-201 washout rate in patients with coronary microvascular disease

Objective:To observe the myocardial 201 Tl washout rate (WR) in patients with decreased coronary flow reserve (CFR) but no visually obstructive coronary lesions.Methods:Twenty three patients (male 13,female 10,aged 57.09 ± 11.83 ) who had atypical chest pain but no detectable heart disease was selected. CFR of coronary arteries were measured, and the coronary arteries were divided into Group A (34 arteries) with CFR≥ 2.5 and Group B (16 arteries) with CFR 2.5 . In addition, according to the manifestation of the electrocardiogram, the 23 patients were divided into Group I (12) with normal electrocardiogram (ECG) and Group II (11) with abnormal manifestation of ST T. Regional myocardial WR of 201 Tl was measured from early and delayed bull's eye images of dipyridamole 201 Tl SPECT.Results:In the 23 subjects with no obviously stenosed coronary arteries, the WR of 201Tl in areas which were affected by these coronary arteries with CFR 2.5 was much lower than that in areas which were supported by those coronary arteries with CFR≥ 2.5 ( 36.11 ± 6.80 )% vs (48.91± 7.75 )%, P 0.01 ). And the myocardial WR of 201 Tl in patients with abnormal manifestation of ST T was also lower than that in subjects with normal ECG. ( 39.25 ± 7.86 )% vs ( 49.56 ± 7.31 )% P 0.01 ).Conclusion:The myocardial WR of 201 Tl is decreased in patients with abnormal CFR (CFR 2.5 ) or ECG but no significant coronary stenosis.