Improved Myocardial Fatty Acid Metabolism After CoronaryAngioplasty ...

Improved Myocardial Fatty Acid Metabolism After CoronaryAngioplasty in Chronic CoronaryArtery Disease Shintaro Yoshida, Makoto Ito, Kenichi Mitsunami and Masahiko Kinoshita First Department oflnternal Medicine, Shiga University ofMedical Science, Otsu, Japan myocardium (5,8,9). According to a previous study by Tamaki

Thisstudyassessedtheutilityof myocardialfattyacidimagingusing et al. (10), decreasedBMIPP uptakerelative to 201Tluptakewas 123II@l@

15-(beta-methyI-p-iodopheny@pentadecanic

acid

often observed in acute myocardial infarction. In addition, coronaryangioplastyin patientswith chroniccoronaryarterydis several recent studies have reported that discordance between ease.Methods Thirty-slghtpafients(18old myocardialinfarction perfusion tracer and BMIPP uptake in the acute stage is and 20 angina pectoris patients) wfth chronic coronary artery predictive for subsequent metabolic recovery and improvement stenosis and 8 control subjects were enrolled in this study. All of left ventricular function (11—14).However, in patients with patientsunderwentsuccessfulangioplasty,andBMIPPSPECTwas chronic and stable CAD, metabolic recovery after reperfusion performedbeforeand after angioplasty.SPECTimageswere di therapy, such as percutaneous transluminal coronary angio vided into 13 segments and scored ViSuallyfrom 0 (normal uptake) plasty (PTCA), has not yet been sufficiently investigated. to 4 (defect).Thedefectscorewascalculatedasthe summalionof Although BMIPP is not rapidly metabolized by beta-oxida the total scores in each patient.The regionalwashoutrate was tion (9), a considerable BMIPP washout rate from the myocar (BMIPP) to evaluate improvement after perCUtaneOuStransluminal

calculatedin both the reperfusedareasand normaluptakeareas dium has been noted (7,8,15). Moreover, an extensive multi usinga bull's-eyemap.Results In nonrestenosispatients,BMIPP

center trial of BMIPP in Japan demonstrated that some CAD patients showed significant fill-in and/or washout on delayed value),whereastheyimprovedsignfficantty onthedelayedimage BMIPP images 3—4hr after injection (16). These results suggest that the myocardial washout rate of BMIPP in ischemic (9.9 ±8.8 compared to 8.2 ±8.7, p < 0.05). In nonrestenosis patients, BMIPP washout rate in reperfused areas after angioplasty myocardium is different from that in normal myocardium. was significantlylowerthan that before angioplastyand the washout Therefore, we hypothesized that the BMIPP washout rate would rate in control subjects (22.9% ±8.4% compared to 31.5% ± be altered when metabolic recovery occurs in ischemic myo 10.6% and 29.5% ±8.0%, p < 0.01 and p < 0.05, respectively). In cardium. This study investigated whether the myocardial uptake restenosis patients, BMIPP washout rate in both reperfused areas and washout rate of BMIPP would be altered after PTCA in defect scores before and after angioplasty dki not change on the initial image (9.6 ±9.3 compared to 9.0 ±9.2, nonsignificant p

andnormaluptakeareasdid notchangeafterangioplasty.Conclu patients with chronic CAD. sion:ThesedatasuggestthatdecreasedBMIPPwashoutrateafter angioplasty indk@ates improved fatty acid uthizationin patients with

chroniccoronaryarterydisease.

MATERIALS AND METhODS

Key Words fatty acid metabolism; iodine-123-15-beta-methyl-piodophenyl-pentadecanic acid; chronic coronary artery disease; coronary angioplasty; restenosis

p@

J NuciMed199839933-938

The study population consisted ofchronic CAD patients meeting the following criteria: 1. Stable CAD without vasospastic angina pectoris or recent myocardial infarction (within 1 mo after onset); 2. No previous coronary intervention or bypass graft surgery; 3. Successfulsingle-or two-vesselPTCA ofthe nativecoronary arteries; and 4. Absenceof repeatPTCA duringthe follow-up period.

Although long-chain fatty acids aremajor substances for energy production in the normal myocardium, fatty acid oxida tion is easily suppressed under ischemic conditions (1). Thus, radionuclide fatty acid imaging may be a useful method of assessing metabolic disorders in patients with coronary artery disease (CAD). PET using I‘C-palmitate has been used to evaluate fatty acid metabolism in ischemic myocardium (2—4). However, PET studies are not widely performed because of the expense, and the use of ‘ ‘C-palmitateis limited by the problem of extensive back diffusion in ischemic myocardium (4). For practical use, ‘231-labeledfatty acid analogs have been devel oped to assess myocardial metabolism with a conventional gamma camera (5—7). Iodine-123-labeled 15-beta-methyl-piodophenyl-pentadecanic acid (BMIPP) is a branched fatty acid analog that has desirable characteristics for SPECT imaging, showing high accumulation and prolonged retention in the ReceivedApr. 23, 1997; revisionaccepted Oct. 9, 1997. For correspondence or reprints contact Shintaro Yosh@a, MD, Fret Department of

Internal Medicine, Shiga Universftyof Med@ Sdence, Tsukinowa-cho, Seta@Otsu, Shiga,520-21, Japan.

FATFY

Thirty-eight patients with CAD (18 old myocardial infarction and 20 effort angina pectoris patients) who met all the criteria for the currentanalysis were enrolled in this study (28 men, 10 women; age range 39—78yr; mean age = 65 yr). The control group consisted of 8 normal volunteers (6 men, 2 women; age range 48—65yr; mean age = 61 yr). Each patient underwent control

coronary angiographyon admission, which showed coronary artery stenosis of >75% of the luminal diameter. Twenty-four patients had single-vessel disease, and 14 patients had two-vessel disease. In each patient, myocardial viability was assessed using dobu tamine stress echocardiography and/or exercise 201Tlscintigraphy in selecting cases for coronary revascularization. Of the total 52 vessels, 45 vessels were dilated by PTCA (the left anterior descending artery in 18 patients, the left circumflex artery in 10 patients and the right coronary artery in 17 patients). This study was approved by our institutional review board, and Acm

METABOLISM

AFTER

ANGIOPLASTY

•Yoshida

Ct a!.

933

LAD: Left anterior descendIng

artery

LCx:Leftcircumflex artery RCA:Rightcoronaryartery midshortaxis apicalshortaxis verticallongaxis FiGURE1.Schematic presentation ofmyocardisi segments usingtheshort axisandverticallong-aas.Theleftventr@ wasdMdedinto13segments. informed consent was obtained from all subjects before they

Bull'sEyeMap RGURE2.Schema@c anatomic display ofthedistribution ofthethreemajor coronaryarteriesinthe bull's-eyepolarmap.

underwent any of the procedures. Coronary Intervention Within 2 wk after control coronary angiography, PTCA was

performed in all patients, each of whom showed stenosis of 50% narrowing at the previous PTCA sites on follow-up coronary angiography (17,18). BMIPP Imaging PrOtOCOl Myocardial SPECT imaging with BMIPP at rest was performed within 1 wk before PTCA in each patient and in each control. BMIPP was prepared and provided by Nihon Medi-Physics Co., Ltd. (Hyogo, Japan). The vial ofBMIPP contained 74 MBq/ml (0.4 mg/ml) ‘231-labeled BMIPP dissolved in ursodeoxycholic acid (7 mg/ml). Under fasting and resting conditions, 111 MBq ( 1.5 ml) ‘23IBMIPPwas injected intravenously and immediately flushed by 10 ml of saline. SPECT images were obtained 20 mm (initial images) and 180 mm (delayed images) after the injection of BMIPP, after the protocol of the multicenter trial of BMIPP in Japan (16), using a rotating gamma camera (model GCA-901A; Toshiba Co., Ltd., Tokyo, Japan) equipped with a low-energy, general-purpose collimator. The energy window was set at 159 keV ±10%.

In

each

SPECT

acquisition,

32

projection

images

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(Initial counts —Delayed counts) x 100. Initial counts

Statistical Analysis All values are presented as mean ±s.d. The differences in population were examined by chi-square test. Student's t-test was used for comparison of paired data. Scheffe's F-test for multiple comparisons was used to detect significant differences, as defined by analysis of variance. A p value of