The Value Of Gated Myocardial Perfusion Imaging For Evaluating Stent Restenoses After Percutaneous Coronary Interventions

Background:Percutaneous coronary interventions (PCI) has been one of the main treatment of coronary artery disease(CAD), but coronary restenosis has always been an important clinical problem after PCI. After successful percutaneous transluminal coronary angioplasty (PTCA), restenosis is observed in 30~50% of patients. The introduction of stent applications after PTCA had demonstrated relatively low rates of restenosis. However, after successful implantation of stents, the rate of restenosis for bare-stent is still up to 20~30%, drug-eluting stent about 10%. Compare with primary coronary artery disease, symptoms of patients with stent restenosis are less obvious, so the clinical diagnosis of stent restenosis is more difficult. But in generally, both of the conditions can cause significant myocardial ischemia, so the risk of cardiac events also increases for patients with restenoses. Therefore, the diagnosis and management of stent restenoses have important clinical significance. In recent years, gated myocardial perfusion imaging (G-MPI) has been a routine practice in clinical. G-MPI can precisely evaluate myocardial ischemia and ventricular function and analyzes the overall and local wall motion and thickening. The value of G-MPI in the diagnosis of myocardial ischemia or coronary heart disease has been recommended in ACC / AHA / ASNC (American College of Cardiology / American Heart Association / American Nuclear Society of Cardiology). But studies for the diagnosis of coronary restenosis with G-MPI is rare up today. Objective: To investigate the diagnostic value of G-MPI for the evaluating of coronary stent restenosis. Method: Sixty-five patients of CAD 3 months after PCI with stent implantation who clinically suspected restenosis were envolled to undergo the two-day protocol of exercise or adenosine stress/rest 99mTc-MIBI G-MPI. G-MPI data were visually evaluated by three experienced observers for ischemia and wall motion, wall thickening and ejection fraction. Reversible or fixed perfusion defects in the area perfused by the stented coronary arteries were considered as restenoses. Repeat contrast coronary angiography (CAG) for all the patients were performed within 1 month before or after the G-MPI study. Those patients receiving target lesion revascularizations after CAG but before G-MPI study were excluded from the study. Stent restenosis was defined as≥50% stenosis in diameter within or less than 5mm outside the stent with CAG study. Result: 105 stents were deployed in 88 coronary arteries in 65 patients. Restenoses were found in 25 patients(38.5%), 31 stents(29.5%) following repeat CAG.①The sensitivity, specificity and accuracy of typical symptoms in diagnosing restenosis were 64.0%,22.5% and 38.5% respectively. The sensitivity, specificity and accuracy of exercise treadmill test(ETT) were 41.2%, 71.9% and 61.2% respectively.②According to target vessel, the sensitivity, specificity and accuracy of G-MPI in diagnosing restenosis were 92.9%,86.7% and 88.6% respectively; according to patients, the sensitivity, specificity and accuracy were 96.0%, 85.0%, 89.2% respectively.③The accuracy of G-MPI in diagnosing restenosis was obviously superior to ETT and clinical symptoms(P<0.01).Conclusion: G-MPI has high accuracy in diagnosing restenosis.