[Effect of collateral circulation on myocardial protection in patients with acute myocardial infarction: comparison of technetium-99m-tetrofosmin myocardial single photon emission computed tomography and coronary angiography].

OBJECTIVES: Evaluation of myocardial blood flow from collateral vessels into the infarct area has been estimated by coronary angiography. In patients with acute myocardial infarction with Thrombolysis in Myocardial Infarction (TIMI) 0 flow, myocardial tracer uptake on single photon emission computed tomography (SPECT) images can predict the collateral blood flow in the infarct area if technetium (Tc)-99m-tetrofosmin was administered before recanalization. The present study investigated whether collateral blood flow evaluated by myocardial scintigraphy is a good predictor of myocardial salvage in patients with acute myocardial infarction. METHODS: The study group consisted of 30 patients (mean age 65 +/- 14 years, 23 males, 7 females) with first acute myocardial infarction and coronary angiography evidence of total occlusion (TIMI 0) within 12 hr after the onset. All patients had one vessel disease related to infarction and TIMI 3 flow after percutaneous coronary intervention (PCI). Tc-99m-tetrofosmin was injected intravenously before the PCI. The regional severity score index (RSSI) was obtained from SPECT using the 17 segment method with the four-point scoring system. Myocardial viability was evaluated by the RSSI obtained from thallium-glucose-insulin infusion SPECT after 1 week and regional wall motion score index obtained from echocardiography during the chronic phase. RESULTS: The patients were divided into two groups according to the angiographic collateral finding. There were no differences in RSSI on thallium-glucose-insulin SPECT and regional wall motion score between the good collateral group (n = 8) and poor collateral group (n = 22). Myocardial Tc-99m-tetrofosmin RSSI was similar in these groups. On the other hand, the patients were divided according to Tc-99m-tetrofosmin scintigraphic evaluation before PCI. RSSI on thallium-glucose-insulin SPECT was significantly greater (0.7 +/- 0.5 vs 1.5 +/- 0.4, p < 0.01) and regional wall motion score was significantly less (1.46 +/- 0.50 vs 2.08 +/- 0.78, p < 0.05) in the lower Tc-99m-tetrofosmin RSSI (< 1.9) group (n = 22) compared with the higher RSSI (> or = 1.9) group (n = 8). In addition, a significant correlation was obtained between Tc-99 m-tetrofosmin RSSI and regional wall motion score index (r = 0.53, p < 0.01). CONCLUSIONS: The collateral flow evaluated by scintigraphy was significantly correlated with myocardial viability.

Noninvasive assessment of coronary microvascular dysfunction using Tc-99m tetrofosmin SPECT in patients with acute myocardial infarction.

BACKGROUND: We investigated whether technetium 99m tetrofosmin (TF) single photon emission computed tomography (SPECT) could predict coronary microvascular dysfunction in patients with acute myocardial infarction. METHODS AND RESULTS: We obtained the regional severity score index (TF-RSSI) using TF SPECT immediately after percutaneous coronary intervention in 25 patients with acute myocardial infarction. Using a Doppler guidewire, we evaluated the deceleration time of diastolic flow velocity (DDT) after percutaneous coronary intervention, and DDT of 600 milliseconds or less was suggested to be an indicator of coronary microvascular dysfunction. Moreover, the chronic regional wall motion score index (RWMSI) was obtained from echocardiography during the chronic phase. There was a good correlation between TF-RSSI and DDT (r = -0.68, P < .01). The optimal cutoff value of TF-RSSI to predict DDT of 600 milliseconds or less was defined as 1.9 or greater (sensitivity, 1.00; specificity, 0.71). The group with poor scintigraphic coronary microvascular function (TF-RSSI > or =1.9, n = 7) demonstrated a significantly shorter DDT (P = .0003), a lower frequency of early systolic retrograde flow (P = .0038), and greater chronic RWMSI (P = .0015) than the group with good scintigraphic coronary microvascular function (TF-RSSI <1.9, n = 15). CONCLUSIONS: Analysis of TF SPECT immediately after percutaneous coronary intervention in patients with acute myocardial infarction is a useful noninvasive method for evaluating coronary microvascular dysfunction.

[Usefulness of technetium-99m tetrofosmin single-photon emission computed tomography for short-term risk stratification in patients with acute chest pain in the emergency room].

OBJECTIVES: High-risk patients with acute coronary syndrome are difficult to distinguish from low-risk patients with chest pain in the emergency room. Technetium-99m (99mTc) tetrofosmin single-photon emission computed tomography (SPECT) was investigated to exclude high-risk patients with chest pain in the emergency room. METHODS: 99mTc-tetrofosmin SPECT was evaluated using a four-point scoring system in 228 patients (144 men, 84 women, mean age 68 +/- 12 years) with chest pain. Negative was defined as the myocardial segments with a defect score (DS) of < 2. The patients were divided into two groups; the negative group with DS < 2 (n = 78) and the positive group with DS > or = 2 (n = 150). Cardiac events (cardiac death, acute myocardial infarction and refractory angina) were evaluated within 30 days of onset. ST-segment elevation or depression > or = 0.1 mV was defined as positive in electrocardiography. The results of SPECT were compared with those of electrocardiography, transthoracic echocardiography and serum cardiac markers (troponin T and creatine kinase-MB) in 95 patients. RESULTS: The negative group had very few cardiac events (three patients with refractory angina) (3.8%). The negative predictive value of cardiac events evaluated by electrocardiography was calculated as 83.1%, whereas the negative predictive value by SPECT was 96.2% (p < 0.01). In addition, the negative predictive value of acute myocardial infarction by SPECT was 100%. The negative predictive values of cardiac events evaluated by SPECT, electrocardiography, transthoracic echocardiography and serum cardiac markers were 95.8%, 81.5% (vs 99mTc-tetrofosmin; NS), 84.9% (NS) and 60.4% (p < 0.05), respectively. CONCLUSIONS: 99mTc-tetrofosmin SPECT is a useful method to exclude high-risk patients among patients with chest pain in the emergency room.