Prediction of Functional Outcome in Stunned Myocardium after Myocardial Infarction using BMIPP and Tetrofosmin Imaging

0 Dr Tetsuya Ueda Fujioka General Hospital , 942-1 Fujioka, Gunma 375-0024, Japan - Downloaded from imr.sagepub.com by guest on October 16, 2014 The Journal of International Medical Research 2009; 37: 367 377 Prediction of Functional Outcome in Stunned Myocardium After Myocardial Infarction using BMIPP and Tetrofosmin Imaging T UEDA1, T TOYAMA2, R SEKI2, H HOSHIZAKI2, S OSHIMA2, K TANIGUCHI2, K ENDO3 AND M KURABAYASHI1 1Department of Medicine and Biological Science, Gunma University, Gunma, Japan; 2Gunma Prefectural Cardiovascular Centre, Maebashi, Japan; 3Department of Diagnostic Radiology and Nuclear Medicine, Gunma University, Gunma, Japan The predictive value of combined 123iodine-labelled 15-(p-iodophenyl)-3R,Smethyl pentadecanoic acid imaging (123IBMIPP) and early technetium-99m (99mTc)tetrofosmin imaging was compared with combined 123I-BMIPP and delayed 99mTctetrofosmin or 123I-BMIPP and thallium201 (201Tl) imaging for functional outcome of stunned myocardium after acute myocardial infarction (AMI) in 37 patients with AMI. All patients underwent successful percutaneous coronary intervention with/ without stenting within 24 h of symptoms. Resting 201Tl, 99mTc-tetrofosmin and 123IBMIPP imaging were performed within 10 days of hospital admission; 99mTctetrofosmin imaging was also performed 6 months later. Segments were mismatched when the 123I-BMIPP score was greater than the 99mTc-tetrofosmin or 201Tl scores, and were matched when all scores were the same. Left ventricular function was estimated using wall motion score. Sensitivity and regional wall motion were significantly better in mismatching 99mTctetrofosmin-early/123I-BMIPP segments than mismatching 201Tl/123I-BMIPP or 99mTc-tetrofosmin-delayed/123I-BMIPP segments. It is concluded that mismatching of 123I-BMIPP and early 99mTctetrofosmin uptake can predict improvement in wall motion of stunned myocardium better than the other two imaging combinations. KEY WORDS: ACUTE MYOCARDIAL INFARCTION; STUNNED MYOCARDIUM; 123I-BMIPP; 99MTC-TETROFOSMIN; 201TL Revascularization using percutaneous coronary intervention (PCI) is a widely established treatment for patients with acute myocardial infarction (AMI) that aims for rapid restoration of infarcted myocardium; the treatment is recognized for its low invasiveness and high effectiveness. Even though devices including a stent have been developed, PCI has greatly helped in reducing the need for restenosis.1 5 Such revascularization treatments aim to re-establish blood flow in Downloaded from imr.sagepu3b.c6om7by guest on October 16, 2014 order to prevent myocardial necrosis and help the recovery of cardiac function. Although a successfully reperfused and viable cardiac region may recover function, it remains a candidate for future cardiac events. It is, therefore, important to assess areas at risk or damaged myocardium when managing patients after reperfusion therapy for AMI. This is because, after a brief episode of severe ischaemia, prolonged myocardial dysfunction with gradual return of contractile activity can occur: a condition known as myocardial stunning. In patients with AMI who receive reperfusion therapy, reversibly injured, functionally stunned myocardium lies adjacent to infarcted myocardium.6 Several clinical studies have described regional perfusion and 123iodine-labelled 15(p-iodophenyl)-3R,S-methyl pentadecanoic acid (123I-BMIPP) uptake in patients with AMI and ischaemia.7 9 A perfusion/ metabolism mismatch, defined as lower 123IBMIPP activity relative to perfusion, is more frequently observed in regions of AMI that are supplied by a revascularized vessel than in non-revascularized regions.7 9 In addition, a discordant 123I-BMIPP decrease is frequently found in areas with wall motion abnormalities and relatively preserved perfusion.8,10 The purpose of this study was to assess the predictive value of combined 123I-BMIPP and early technetium-99m (99mTc)-tetrofosmin imaging for functional outcome of stunned myocardium in patients with AMI, and to compare it with combined 123I-BMIPP and delayed 99mTc-tetrofosmin imaging and combined 123I-BMIPP and thallium-201 (201Tl) imaging. Patients and methods PATIENTS Patients with AMI who underwent successful PCI, with or without stenting, within 24 h of symptom onset were recruited into this study. A diagnosis of AMI was based on the following criteria: acute chest pain lasting 30 min; serum creatine kinase activity 500 U/l; and development of abnormal electrocardiographic Q waves. All patients provided informed consent in accordance with the guidelines set by the Gunma Prefectural Cardiovascular Centres Human Clinical Study Committee. Patients who fulfilled the following criteria were included in the statistical analysis: successful PCI with or without coronary stenting, with angiographic confirmation of 25% residual stenosis; no significant stenosis in other vessels; good image quality for all radiotracer studies during the subacute and chronic periods; no restenosis based on coronary angiography (CAG) at 6 months after admission. STUDY PROTOCOL All patients underwent cardiac catheterization through a femoral approach following injection of 5000 IU heparin. CAG and PCI were performed following injection of 2.5 mg isosorbitrate into the coronary artery. Heparin administration continued for 1 2 days and, at the same time, nitroglycerin was continuously infused at 3 ml/h over 1 2 days. All patients were maintained on a regimen of aspirin (100 mg/day) and ticlopidine (200 mg/day). Scintigraphic studies (resting 201Tl singlephoton emission computed tomographic [SPECT] imaging, resting 99mTc-tetrofosmingated SPECT and 123I-BMIPP SPECT performed in that order) were carried out within 10 days of admission for AMI at 2-day intervals after a 12-h overnight fast in the absence of anti-anginal medication. Resting 99mTc-tetrofosmin SPECT using the Quantitative Gated SPECT (QGS) program (Cedar-Sinai Medical Center, Los Angeles, Downloaded from imr.sagepu3b.c6om8by guest on October 16, 2014 CA, USA)11 13 and CAG were also performed at 6 months follow-up. For 201Tl SPECT, all patients received an intravenous (IV) injection of 111 MBq 201Tl (Nihon Mediphysics, Chiba, Japan) and underwent SPECT imaging 15 min after 201Tl injection. For 99mTc-tetrofosmin-gated SPECT, all patients received an IV injection of 740 MBq 99mTc-tetrofosmin (Nihon Mediphysics) while sitting upright. Gated SPECT images were acquired 15 min (early) and 4 h (delayed) after injection. The RR interval was divided into 16 subintervals for gated SPECT. For 123IBMIPP SPECT, all patients received an IV injection of 111 MBq of 123I-BMIPP (Nihon Mediphysics) while sitting upright. SPECT images were acquired 15 min after injection. MYOCARDIAL SPECT IMAGING Myocardial SPECT imaging was performed using a Prism 3000 (Picker, Cleveland, OH, USA) three-headed SPECT system with lowenergy, all-purpose resolution, parallel-hole collimators. The det (...truncated)