Clinical Application Of Adenosine-Stress Myocardial Perfusion Imaging In Coronary Artery Disease Patients

Objectives1. To validate the safety of adenosine stress study.2. To evaluate the efficacy of the adenosine-SMPI in diagnosing, risk stratifying and therapeutic decision-making for patients with CAD (coronary artery disease).3. To estimate the value of adenosine-SMPI in patients follow-up after PCI.4. To define the prognostic value of the adenosine-SMPI in patients with CAD.Materials and MethodsFrom 2004-06 to 2006-06, 208 patients with CAD or highly suspected with CAD underwent adenosine-SMPI (total 232 scans).Pharmacological stress was performed by using adenosine infusion (0.14mg/kg/min for 6min) and continuous monitoring with ECG and BP. ^99mTc-MIBI was injected at the end of 3min of infusion, and SPECT imaging was started about 90min after the end of the adenosine infusion. MPI was performed next day, if there was any abnormality observed in SMPI.Semi-quantitative visual analysis was performed according to the standardized myocardial 17 segments for tomographic imaging and 5-point scoring system. A summed stress score (SSS) was obtained by adding the scores of 17 segments together. The sum of the differences between stress and rest images was defined as the summed difference score (SDS).119 cases underwent coronary angiography (CAG) within 1 month before or after adenosine-SMPI. Among them, in 20 cases adenosine-SMPI was performed both before and after PCI within 1 week, and in 31 cases≥3 months after PCI.Patients' follow-up was performed (with phone call) by nuclear medicine physicians without the knowledge of other studies of the patients about 1 year after adenosine-SMPI. Cardiac death and non-fatal myocardial infarction were considered HCE ( hard cardiac events) and late revascularization procedures (≥3 months after adenosine-SMPI) as SCE ( soft cardiac events).Patients were divided into four groups according to the purposes of this study.1. Safety evaluation: all 208 cases of SMPI2. Efficacy evaluation: 119 cases who underwent CAG within 1 month before or after adenosine-SMPI.3. Follow-up after PCI.1) Short-term: 20 cases with adenosine-SMPI both before and after PCI within 1 week.2) Long-term: 31 cases with adenosine-SMPI≥3 months (7.5±10) post-PCI.4. Prognositic value evaluation: 142 in-patients with phone call follow-up.Results:1. The safety of the adenosine-SMPI76.9% (160/208) of the patients complained of side effects during the adenosine-SMPI. The most common side effects were shortness of breath, dizziness, and palpitation, while chest pain, abdominal pain, nausea, ST-T depressing, and AVB II°were infrequent. Most of these side effects resolved spontaneously within several minutes after discontinuing the adenosine infusion.2. CAG and PCIAmong the 119 cases who underwent CAG, there were 80 positive cases (24 with single coronary artery disease, 32 with dual coronary artery disease and 24 with triple coronary artery disease) and 39 negative cases. 41 cases received PCI after adenosine-SMPI and 74 stents were implanted.3. The efficacy of adenosine-SMPI to evaluate ischemia.The detecting rates of adenosine-SMPI for slightly narrowing (50%～69%) and severely narrowing (70%～100%) vessels were 36.3% (12/33) and 71.1% (91/128) respectively. The difference was statistically significant (χ²= 27.456, P<0.01).Compared to CAG with vessels narrowing≥50%, the sensitivity, specificity, accuracy, positive prognostic value and negative prognostic value of the adenosine-SMPI in diagnosing CAD were 81.3%, 84.6%, 82.3%, 91.5% and 68.8% respectively. The increase in the number of diseased coronary arteries increased the detectability of adenosine-SMPI. The sensitivity, specificity, accuracy of the adenosine-SMPI in detecting individual coronary artery disease were 64.0%, 80.1%, 72.8%. The detecting rate decreased as the number of the involved coronary arteries increased.Compared to CAG with vessels narrowing≥70%, the sensitivity of adenosine-SMPI in diagnosing CAD increased to 89.7%. The detecting rate of each coronary branch also increased. However, the differences between these 2 groups had no statistical significance. The reason was that the number of vessels narrowing≥50% included also the number of vessels narrowing≥70%. Actually it was the comparison of 12+91 to 91 vessels.4. The value of adenosine-SMPI in the patients' follow-up after PCI.1) Short-term: 20 cases underwent adenosine-SMPI both before and after PCI within 1 week. The scans showed that the myocardial perfusion of reversible segments and irreversible segments increased to 90.9% (40/44), 41.3% (25/58) respectively.2) Long-term: 31 cases underwent adenosine-SMPI≥3 months( 7.5±10m) after PCI, the sensitivity, specificity, accuracy of adenosine-SMPI in diagnosing ischemia, caused by either newly developed stenosis or restenosis, were 100%, 80%, 96.8% respectively.5. The prognostic value of the adenosine-SMPI for CAD142 in-patients with a mean follow-up of 361.5±21.5d, 5 HCE and 49 SCE occurred. Statistics indicated that SSS was the predictor of HCE, and old myocardial infarction was also significantly related to HCE.ConclusionA positive SMPI is a valuable index for revescularisation, but a negative result cannot rule out the diagnosis of CAD. Therefore, SMPI is more useful in risk stratification and therapeutic decision-making than as a screening study of CAD patients. It is also valuable in post-PCI patients (both short-term and long-term follow-up). In addition, since SSS is an independent predictor of HCE, SMPI has an important value for the prognosis of CAD patients.