Coronary vasodilator reserve: a clue to the explanation of (201)Tl redistribution patterns early after successful primary stenting for acute myocardial infarction

Change with exercise in QT dispersion in infarct-related myocardium after angioplasty

BACKGROUND

The aim of this study was to evaluate the relationship between exercise-induced QT dispersion and condition of infarct-related myocardium including myocardial scar after angioplasty assessed with exercise perfusion single photon emission computed tomography (SPECT).

METHODS

Exercise thallium-201 SPECT was performed 6 months after successful direct angioplasty in 67 male patients (60.6 +/- 11.5 years), who had Q wave infarction resulting from single vessel disease, and the number of perfusion defect areas (DS) was measured at rest and exercise together with QT (QTc) dispersion.

RESULTS

In 52 patients with resting perfusion defects, the exercise-induced change in DS was correlated to the change in QT (or QTc) dispersion (r = -0.51 or r = -0.531, p < 0.0001). When the patients were grouped according to the patterns of transient perfusion defect, there were significant differences in DeltaQT dispersion and DeltaQTc dispersion among infarct-related three groups (reverse, fixed, and partial redistributions) and normal volunteers (DeltaQT dispersion; -5.7 +/- 12.7 ms in 13 patients with reverse redistribution, -16.3 +/- 13.1 ms in 30 patients with fixed redistribution, -28.9 +/- 29.5 ms in 9 patients with partial redistribution, and +3.4 +/- 20.9 ms in 12 normal volunteers, p = 0.0098; DeltaQTc dispersion; +18.2 +/- 20.8 ms, +1.4 +/- 16.7 ms, -15.4 +/- 30 ms, and +19 +/- 27.5 ms, p = 0.0017, respectively). DeltaQTc dispersion estimated the SPECT image patterns (p = 0.0002) with a sensitivity of 67.3%, a specificity of 83.7% and an accuracy of 78.2%.

CONCLUSIONS

The change with exercise in QT dispersion may help detect the condition of infarct-related myocardium after angioplasty.

Contractile reserve, thallium-201 reverse redistribution and mismatch between perfusion and metabolism in reperfused infarct-related myocardium with delayed and incomplete functional recovery

We investigated simultaneously the correlations between dobutamine-induced contractile reserve (CC), thallium-201 reverse redistribution (RR) and a mismatch between perfusion and metabolism (MM) to the magnitude of functional recovery. In 32 patients with coronary angioplasty early after infarction, echocardiography was performed at low-dose dobutamine stress within 1 week and at resting state at 1 month. Thallium-201/iodine-123 beta-methyl-iodophenyl pentadecanoic acid (BMIPP) dual-isotope single photon emission tomography was performed at 1 month. Wall motion and the uptake of each tracer were scored as 0 to 2 in the infarct-related segments, and CC, RR, and MM were evaluated in the infarct-related segments. In 71 akinetic or dyskinetic segments before reperfusion, the initial thallium-201 uptake and initial BMIPP uptake scores and the 4 hour redistribution thallium-201 uptake scores were less severe in the group with complete functional recovery (group A), followed by the group with incomplete recovery (group B) and then the group with no recovery (group C) (each P < 0.0001). CC was the greatest in group A, followed by group B, and then group C (76.2% in 16/21, 60% in 15/25, 36% in 9/25, P = 0.0212). RR and MM were greater in group B (52% in 13 and 64% in 16) than in groups A and C (19% in 4 and 8% in 2, 33.3% in 7 and 24% in 6, P = 0.0013 and P = 0.0113). The intensity of functional damage reflects perfusion and metabolism, but the delayed and incomplete functional recovery after reperfusion may be closely related to RR, MM, and CC.