Prediction of functional recovery and prognosis in patients with acute myocardial infarction by 123I-BMIPP and 201Tl myocardial single photon emission computed tomography: a multicenter trial

Underrecognized Utility of 123I-BMIPP in CAD Diagnosis Outside of Japan

123I-BMIPP (Iodine-123 labeled beta-methyl-p-iodophenyl-pentadecanoic acid) is a radiotracer that facilitates non-invasive assessment of myocardial fatty acid metabolism through single photon emission computed tomography imaging. Given that fatty acids serve as one of the primary energy sources for cardiac muscle, reduced uptake of 123I-BMIPP offers valuable insights into the pathophysiology of various cardiac conditions, particularly in coronary artery disease (CAD). Despite its reported efficacy, the use of 123I-BMIPP remains limited outside Japan, primarily due to regulatory and supply challenges. However, in Japan, 123I-BMIPP is clinically utilized for CAD patients with various ischemic conditions as the protocol does not require stress tests or contrast iodine and has a relatively short acquisition time. This review highlights the clinical applications of 123I-BMIPP across various conditions and aims to promote its broader adoption in clinical practice, both in Japan and internationally.

Dual-radionuclide in vivo imaging of micro-metastasis and lymph tract with submillimetre resolution

Multi-radionuclide in vivo imaging with submillimetre resolution can be a potent tool for biomedical research. While high-resolution radionuclide imaging faces challenges in sensitivity, multi-radionuclide imaging encounters difficulty due to radiation contamination, stemming from crosstalk between radionuclides and Compton scattering. Addressing these challenges simultaneously is imperative for multi-radionuclide high-resolution imaging. To tackle this, we developed a high-spatial-resolution and high-energy-resolution small animal single-photon emission computed tomography (SPECT) scanner, named CdTe-DSD SPECT-I. We first assessed the feasibility of multi-tracer SPECT imaging of submillimetre targets. Using the CdTe-DSD SPECT-I, we performed SPECT imaging of submillimetre zeolite spheres absorbed with 125I- and subsequently imaged 125I-accumulated spheroids of 200-400 µm in size within an hour, achieving clear and quantitative images. Furthermore, dual-radionuclide phantom imaging revealed a distinct image of the submillimetre sphere absorbed with 125I- immersed in a 99mTc-pertechnetate solution, and provided a fair quantification of each radionuclide. Lastly, in vivo imaging was conducted on a cancer-bearing mouse with lymph node micro-metastasis using dual-tracers. The results displayed dual-tracer images of lymph tract by 99mTc-phytic acid and the submillimetre metastatic lesion by 125I-, shown to align with the immunofluorescence image.

Simultaneous visualization of multiple radionuclides in vivo

The insufficient energy and spatial resolutions of radionuclide imaging with conventional scintillation detectors restrict the visualization of multiple radionuclides and of microstructures in tissue. Here we report the development and performance of an imaging system equipped with a cadmium telluride diode detector that achieves an energy resolution of 1.7% at 140 keV and a spatial resolution of 250 μm. The combination of high-resolution spectra fitted to an X-ray analysis model of the emission lines of the radionuclides in a chosen energy band allowed us to accurately determine individual radiation activities from three radionuclides to simultaneously visualize thyroid tissue (via intravenously administered iodine-125), mandibular lymph nodes (via the intramuscular injection of indium-111) and parotid lymph nodes (via a subcutaneous injection of technetium-99m) in mice. Multi-radionuclide imaging may find advantageous applications in biomedical imaging.

Impact of accelerated washout of Technetium-99m-sestamibi on exercise tolerance in patients with acute coronary syndrome: single-center experience

Technetium-99m-sestamibi (^99mTc-sestamibi) single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) in patients with acute coronary syndrome (ACS) could be used to assess area-at-risks, as well as myocardial infarct or saved sizes. In patients with ACS, accelerated washout of ^99mTc-sestamibi during early and delayed imaging in the acute phase may suggest mitochondrial dysfunction in the injured but salvaged myocardium. However, the link between ^99mTc-sestamibi accelerated washout and exercise tolerance is unknown. The purpose of this study was to investigate a possible association between ^99mTc-sestamibi accelerated washout and exercise tolerance in acute ACS patients as they progressed into the chronic phase. One hundred and sixty-five patients with ACS who underwent ^99mTc-sestamibi SPECT MPI during the acute phase were recruited. On this basis, we calculated the total perfusion deficits (TPDs) for early (1 h after tracer injection) and delayed (4 h after tracer injection) images using automated quantification software. We then subtracted the early TPDs from the delayed TPDs to calculate the ΔTPD. We conducted a cardiopulmonary exercise test in acute and chronic phases. We divided two groups according to the median ΔTPD (the ΔTPD ≥ 4 group and the ΔTPD < 4 group) and compared anaerobic threshold (AT; ml/kg/min) between the groups. For anaerobic threshold (AT) improvement in data analysis, we employed multivariate logistic regression analysis. A total of 101 ST-segment elevation myocardial infarctions, 36 non-ST-elevation myocardial infarctions, and 28 unstable angina pectoris events were reported as ACS. From acute phase (10.8 ± 4.2 ml/kg/min) to chronic phase (11.9 ± 2.3 ml/kg/min), the AT in the ΔTPD ≥ 4 group was significantly increased (p < 0.0001). This trend was also seen in the ΔTPD < 4 group from acute (11.4 ± 1.8 ml/kg/min) to chronic phase (12.1 ± 2.2 ml/kg/min, p = 0.015). AT was lower in the ΔTPD ≥ 4 group in the acute phase (p = 0.027), but there was no difference in AT between the two groups in the chronic phase (p = 0.60). ΔTPD and the absence of diabetes were both independent predictors of AT improvement in multivariate logistic regression analysis. Receiver-operating characteristic curve analysis determined that ΔTPD = 6 was the best cut-off value, with 60.0% sensitivity and 71.4% specificity, respectively. The accelerated washout of ^99mTc-sestamibi in patients with ACS during the acute phase could help to predict improvement in exercise tolerance in the chronic phase.

Preliminary quantitative evaluation of radiation-induced DNA damage in peripheral blood lymphocytes after cardiac dual-isotope imaging

DNA double-strand breaks (DSBs) of peripheral blood lymphocyte were prospectively assessed in 9 patients who were injected with ²⁰¹Tl-chloride and ¹²³I-beta-methyl-p-iodophenyl-pentadecanoic acid in dual-isotope imaging. Phosphorylated H2AX (γH2AX) was used as a biomarker for detecting DSBs, and the mean number of γH2AX foci per cell was measured microscopically. Mean γH2AX foci before administration of radiopharmaceuticals and at 3, 6, and 24 h following administration were 0.22 ± 0.34, 0.10 ± 0.14, 0.59 ± 0.46, and 0.52 ± 0.40, respectively (p = n.s. for all combinations).

Discrepancy between myocardial perfusion and fatty acid metabolism following acute myocardial infarction for evaluating the dysfunctional viable myocardium

OBJECTIVE

Following acute myocardial infarction (AMI) the area of myocardial perfusion and metabolism mismatch is designated as dysfunctional viable myocardium. (123)I-beta-methyl iodophenyl pentadecanoic acid (BMIPP) is clinically very useful for evaluating myocardial fatty acid metabolism, and (99)mTc-Tetrofosmin (TF) is a widely used tracer for myocardial perfusion. This study was designed to evaluate the degree of discrepancy between BMIPP and TF at the subacute state of AMI.

METHODS

Fifty-two patients (aged 59 ± 10 years; mean 46 years) with AMI were enrolled, and all of them underwent percutaneous coronary intervention (PCI). Patients were classified according to ST-T change and PCI timing. (123)I-beta-methyl iodophenyl pentadecanoic acid and TF cardiac scintigraphy were performed on 7 ± 3.5 days of admission using a dual headed gamma camera. Perfusion and fatty acid metabolism defect were scored on a 17 segments model.

RESULTS

The mean BMIPP defect score on early and delayed images were 16.67 ± 10.19 and 16.25 ± 10.40, respectively. The mean TF defect score was 10 ± 7.69. Defect score of BMIPP was significantly higher than that of the TF (P < 0.0001; 95% CI 4.32-7.02), and there was a strong correlation between perfusion and metabolism defect score (r = 0.89, P < 0.00001). Forty-seven (90%) patients showed mismatched defect (BMIPP > TF), and 5 (10%) patients showed matched defect (BMIPP = TF). Mismatched defect score (MMDS) was significantly higher in patients with ST-segment elevation myocardial infarction (STEMI) than that of non-ST-segment elevation myocardial infarction (NSTEMI) (P < 0.041; 95% CI 0.11-5.19).

CONCLUSION

At the subacute state of AMI, most of the patients showed perfusion-metabolism mismatch, which represents the dysfunctional viable myocardium, and patients with STEMI showed higher mismatch.

Prognostic value of myocardial metabolic imaging with BMIPP in the spectrum of coronary artery disease: a systematic review

BACKGROUND

We conducted a systematic review to summarize the current literature on the prognostic value of BMIPP imaging, fatty-acid metabolic imaging, for the prediction of cardiovascular events in coronary artery disease.

METHODS AND RESULTS

Electronic databases (including Japanese medical literature search engines) were searched by a Japanese investigator using a predefined search strategy. Eleven studies, all conducted in Japan, were included in the meta-analysis. In three studies involving 541 patients with suspected acute coronary syndrome who were excluded for acute myocardial infarction (AMI), an abnormal finding on BMIPP imaging was significantly associated with future hard events (cardiac death or non-fatal myocardial infarction). The negative predictive value of BMIPP imaging for future hard events was 98.9% (96.8-99.7%) over 3.5 years. In six studies involving 542 patients with AMI, a larger defect on BMIPP imaging was significantly associated with future hard events. The prognostic value of perfusion-metabolism mismatch compared with myocardial perfusion imaging was dependent upon the relative timing of BMIPP imaging, revascularization, and myocardial perfusion damage.

CONCLUSIONS

BMIPP imaging is useful for the risk stratification of patients with coronary artery disease, particularly patients with acute chest pain.

Metabolic imaging using SPECT

INTRODUCTION

In normal condition, the heart obtains more than two-thirds of its energy from the oxidative metabolism of long chain fatty acids, although a wide variety of substrates such as glucose, lactate, ketone bodies and amino acids are also utilised. In ischaemic myocardium, on the other hand, oxidative metabolism of free fatty acid is suppressed and anaerobic glucose metabolism plays a major role in residual oxidative metabolism. Therefore, metabolic imaging can be an important technique for the assessment of various cardiac diseases and conditions.

MATERIALS AND METHODS

In SPECT, several iodinated fatty acid traces have been introduced and studied. Of these, (123)I-labelled 15-(p-iodophenyl)3-R, S-methylpentadecanoic acid (BMIPP) has been the most commonly used tracer in clinical studies, especially in some of the European countries and Japan.

RESULTS AND DISCUSSION

In this review article, several fatty acid tracers for SPECT are characterised, and the mechanism of uptake and clinical utility of BMIPP are discussed in detail.

Increase in electrocardiographic R-waves after revascularization in patients with acute myocardial infarction

BACKGROUND

The physiological mechanism of the increase in the electrocardiographic (ECG) R-wave voltage after revascularization in patients with acute myocardial infarction (MI) needs to be elucidated.

METHODS AND RESULTS

One hundred and thirty-eight MI patients (83: anterior MI, 45: inferior MI, 10: lateral MI) underwent ECG and echocardiography in both the acute and subacute phases after emergency revascularization, as well as a resting thallium-201/iodine-123 15-p-iodophenyl-3-(R,S)-methyl pentadecanoic acid myocardial scintigraphy in the acute phase. The total sum of the R-wave voltage (SigmaR) was calculated over multiple leads on ECG for each infarcted lesion. Scintigraphic defect on each tracer was expressed as the percentage (%) defect of the total left ventricular (LV) myocardium. The % defect-discordance on both images in the acute phase and the % increase in SigmaR and the absolute increase in LV ejection fraction from the acute to the subacute phase (DeltaEF) were also calculated. The SigmaR in the subacute phase was significantly greater than that in the acute phase (p<0.0001). The % increase in SigmaR significantly correlated with the DeltaEF (r=0.57, p<0.0001). The % increase in SigmaR also correlated with the % defect-discordance (r=0.68, p<0.0001).

CONCLUSIONS

The increase in the ECG R-wave voltage reflects not only the improvement in myocardial perfusion but also the presence of salvaged myocardium after revascularization in acute MI patients.

Serial alterations and prognostic implications of myocardial perfusion and fatty acid metabolism in patients with acute myocardial infarction

BACKGROUND

Impaired fatty acid metabolism the myocardial infarction (MI)-related area has prognostic value, but can alter over time. The aim of this study was to correlate alterations in myocardial fatty acid uptake and perfusion assessed by serial imaging with future outcomes in post-MI patients.

METHODS AND RESULTS

Following 2 imaging procedures using 15-4-iodophenyl-3-(R,S)-methylpentadecanoic acid (BMIPP) and perfusion tracers at an 11-month interval, 97 patients with acute MI were followed up for 33 months with respect to the primary endpoints of death, non-fatal MI and heart failure. Regional tracer uptake was semi-quantified for both the MI-related and remote coronary territories. A large BMIPP defect relative to a perfusion defect appeared on MI-related coronary territories. Thirteen patients with cardiac events had a greater prevalence of large BMIPP and perfusion defect scores for the MI-related areas on the first scan, previous MI, diabetes mellitus, and worsening of perfusion tracer uptake in the MI-related area than those without cardiac events. Multivariate analysis identified worsening perfusion in the MI-related area on the second scan, a large BMIPP defect in the same area on the first scan and previous MI as significant predictors with chi-square values of 3.48, 6.41 and 6.84, respectively. A combination of 3 predictors significantly (p<0.05) increased the global chi-square value to 15.45 compared with each chi-square value.

CONCLUSIONS

The size of the infarct-related risk area assessed by early cardiac BMIPP imaging and deterioration of perfusion tracer uptake in the compromised area for the first 12 months following acute MI are related to future cardiac events, indicating a rationale for identifying metabolically damaged but viable myocardium for further risk stratification of post-MI patients.

Relationship between the mismatch of 123I-BMIPP and 201Tl myocardial single-photon emission computed tomography and autonomic nervous system activity in patients with acute myocardial infarction

The purpose of this study was to elucidate the relationship between the mismatch of thallium-201(Tl) and iodine-123-beta-methyl-iodophenyl-pentadecanoic acid (BMIPP) myocardial single-photon emission computed tomography (SPECT) and autonomic nervous system activity in myocardial infarction (MI) patients. The subjects were 40 patients (34 males, 6 females) who underwent examinations by 123I-BMIPP and 201Tl myocardial SPECT imaging and 24-hour Holter monitoring within a 3-day period 3 weeks after the onset of their first MI. R-R intervals were analyzed every hour over a period of 24 hours by fast Fourier transformation (FFT). High frequency (HF) and low frequency (LF) were defined as markers of cardiac vagal activity in the former and the LF/HF ratio as sympathetic activity. Greater or more extensive decreases in the BMIPP image than that in the Tl image were defined as a positive mismatch. Patients were divided into positive and negative mismatch groups of 20 patients each. There were no significant differences between the 2 groups in age, sex, site of infarction, max CK (creatine kinase), max CK-MB, or left ventricular ejection fraction. The incidences of clinical signs suggesting residual myocardial ischemia were significantly greater in the positive than in the negative mismatch group (P < 0.05). The mean values for HF over the entire 24-hour period and over the 5-hour nocturnal period (0-5 AM) in the positive mismatch group were both significantly lower than those in the negative mismatch group (P < 0.001 in both groups). The 24-hour mean HF and mean nighttime HF in patients with signs of residual ischemia were both significantly lower than in those without signs of residual ischemia in the positive mismatch group (P < 0.05 in both groups). The mean LF/HF ratio for both the entire 24-hour and the nocturnal period in the positive mismatch group were significantly higher than those in the negative mismatch group (P < 0.001, P < 0.05, respectively). The daily profile of hourly HF measurements was significantly lower in the positive mismatch group than in the negative mismatch group (P < 0.02). The mean values of HF for 24-hour and 5-hour periods were significantly lower in patients with signs of residual ischemia in the positive mismatch group than in those with signs of residual ischemia in the negative mismatch group (P < 0.01, P < 0.02, respectively). There were no significant differences between the patients with signs of residual ischemia in the negative mismatch group and those without signs of residual ischemia in the positive and negative mismatch group with regard to the mean values of HF and the LF/HF ratio measured every hour for 24 hours and 5 hours. It is concluded from the present study that the findings of a mismatch on 123I-BMIPP and 201Tl myocardial SPECT 3 weeks after a first acute myocardial infarction with uncomplicated moderate or severe heart failure and decreased heart rate variability are related to residual myocardial ischemia. A combined assessment of heart rate variability in 24-hour Holter ECG monitoring and perfusion-metabolism mismatch in 123I-BMIPP and 201Tl myocardial SPECT is useful for determining residual myocardial ischemia in the follow-up of those with acute myocardial infarction.

Surveillance study for creating the national clinical database related to ECG-gated myocardial perfusion SPECT of ischemic heart disease: J-ACCESS study design

BACKGROUND

ECG-gated myocardial perfusion SPECT is widely applied to diagnose ischemic heart disease, and such findings are useful to predict patient prognosis. However, Japan does not have a database that correlates SPECT image findings with the prognosis of patients who have ischemic heart disease.

METHODS

A large-scale clinical study involving 117 medical facilities throughout Japan was established to survey the clinical background and image findings of patients who have undergone ECG-gated stress perfusion SPECT. These patients were followed up for three years to investigate the occurrence of cardiac events.

RESULTS

The 4,629 registered patients comprised 2,989 males (age 64.9 +/- 10.3 y, mean +/- SD) and 1,640 females (age 67.2 +/- 9.7 y). The most frequent complication was hypertension (54.5%), followed by hyperlipidemia (47.2%) and diabetes (29.4%). Percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) was conducted on 1,925 of the patients. SPECT examinations were ordered for further examination of chest pain (32.8%), periodic follow-up after coronary artery intervention (24.2%), screening for coronary artery disease (15.1%), follow-up of old myocardial infarction (14.9%), more detailed investigation of ECG or echocardiographic abnormalities (13.1%), etiological assessment of heart failure (1.6%), and further inspection for acute coronary syndrome (0.3%). The method of inducing stress was most often exercise loading at 68.8%, and infusion of either dipyridamole (14.6%) or adenosine triphosphate (ATP, 13.8%). The most frequently applied amount of 99mTc-tetrofosmin was an initial dose of 200 to 300 MBq combined with a second dose of 700 to 800 MBq (37.7%). The mean doses were 305 +/- 81 at the initial and 709 +/- 132 MBq at the second administration. A history of angina pectoris (41.2%) was the most frequent, followed by myocardial infarction (29.5%).

CONCLUSIONS

During the two years of follow-up after registration, 46 of the 4,629 subjects have discontinued or dropped out, 134 have died, and 4,449 (97.8%) continue to undergo follow-up investigations. A complete report will be presented when the follow-up data for 3 years have been compiled and analyzed.

Prediction of functional improvement of ischemic myocardium with (123I-BMIPP SPECT and 99mTc-tetrofosmin SPECT imaging: a study of patients with large acute myocardial infarction and receiving revascularization therapy

BACKGROUND

(18)F-fluorodeoxyglucose (FDG) positron-emission tomography (PET) is assumed to be the most useful method of evaluating the viability of the myocardium, but its use is limited by the need for a cyclotron. In the present study, the ability of a combination of (99m)Tc-tetrofosmin (TF) and (123)I-beta-methyliodophenyl pentadecanoic acid (BMIPP) single-photon emission computed tomography (SPECT), a combination of (18)F-FDG PET and (123)I-BMIPP SPECT, and a combination of (18)F-FDG PET and (99m)Tc-TF SPECT were compared to predict functional improvement of ischemic myocardium after a large acute myocardial infarction (AMI).

METHODS AND RESULTS

Ten patients with large AMI were studied by (99m)Tc-TF SPECT, (123)I-BMIPP SPECT and (18)F-FDG PET within 3 weeks. Six months later, (99m)Tc-TF imaging was performed. All patients underwent successful revascularization, and had no restenosis. Regional tracer uptake was scored using a 4-point scale in 20 segments of the SPECT and PET images. When the defect score of (123)I-BMIPP SPECT exceeded the defect score of (99m)Tc-TF SPECT or (18)F-FDG PET by 1 point or more, and when the defect score of (99m)Tc-TF SPECT exceeded the defect score of (18)F-FDG PET by 1 point or more, the segment was considered to show mismatching. When the defect score was the same in 2 tracers, the segment was considered to show matching. (99m)Tc-TF imaging at 3 weeks and 6 months used quantitative gated SPECT (QGS) to score wall motion using a 6-point scale (-1= dyskinesis, 0= akinesis, 1= severe hypokinesis, 2= moderate hypokinesis, 3= mild hypokinesis, and 4= normokinesis). The sensitivity of the combination of (123)I-BMIPP and (99m)Tc-TF imaging in predicting functional improvement was 61%, that of (18)F-FDG PET and (123)I-BMIPP SPECT was 94%, and that of (18)F-FDG PET and (99m)Tc-TF SPECT was 76%. The specificity of the combination of (123)I-BMIPP and (99m)Tc-TF imaging in predicting functional improvement was 83%, that of (18)F-FDG PET and (123)I-BMIPP SPECT was 40%, and that of (18)F-FDG PET and (99m)Tc-TF SPECT was 49%. The accuracy of the combination of (123)I-BMIPP and (99m)Tc-TF imaging in predicting functional improvement was 70%, that of (18)F-FDG PET and (123)I-BMIPP SPECT was 71%, and that of (18)F-FDG PET and (99m)Tc-TF SPECT was 63%.

CONCLUSION

The combination of (123)I-BMIPP and (99m)Tc-TF imaging is a practical modality for predicting the functional improvement of ischemic myocardium after a large AMI.

Scintigraphic evaluation of cardiac metabolism in multicentric Castleman's disease

A 72-year-old woman had insidious onset of heart failure, and was diagnosed as multicentric Castleman's disease. She underwent myocardial imaging with technetium-99m tetrofosmin, 1-123 beta-methyl-iodophenyl pentadecanoic acid (BMIPP). Technetium-99m tetrofosmin studies showed almost normal uptake of the left ventricular myocardium indicating normal myocardial perfusion. 1-123 BMIPP showed reduced uptake in the apical segment of the myocardium, indicating regional fatty acid metabolic abnormalities.

Ischemic "memory image" in acute myocardial infarction of 123I-BMIPP after reperfusion therapy: a comparison with 99mTc-pyrophosphate and 201Tl dual-isotope SPECT

Ischemic "memory image" is a phenomenon of 123I-15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) in which an area at risk of acute myocardial infarction (AMI), could be detected as a defect in a couple of weeks even after successful reperfusion therapy. The purpose of this study was to clarify the incidence of the ischemic "memory image" of 123I-BMIPP in patients with AMI by comparing 99mTc-PYP and 201Tl dual-isotope SPECT. Materials consisted of 14 patients with successfully reperfused AMI and 20 patients with old myocardial infarction (OMI). All AMI patients underwent PYP/Tl dual-isotope SPECT within 1 week after the onset of AMI, and BMIPP SPECT was performed within 1 week after the PYP/Tl dual-isotope SPECT. The extent and severity of the defect of BMIPP and Tl were visually scored into four grades: 0 = no defect to 3 = large or severe defect. These scores were compared. PYP positive AMI lesions were concordant with BMIPP defects (13/14). In AMI, both the extent and severity scores of BMIPP were higher than 201Tl (p < 0.001). Differences (BMIPP - Tl) of extent and severity scores were greater in AMI than in OMI (p < 0.001). In conclusion, the ischemic "memory image" obtained by means of the BMIPP is a common phenomenon (13/14) in AMI, and helpful in evaluating the area at risk.

Noninvasive identification of myocardial sympathetic and metabolic abnormalities in a patient with restrictive cardiomyopathy--in comparison with perfusion imaging

A 42-year-old man had the insidious onset of heart failure, and was diagnosed as having restrictive cardiomyopathy. Doppler echocardiography study showed short deceleration time of the E wave and short isovolumic relaxation time on transmitral Doppler flow. He underwent Tl-201, I-123 beta-methyl-iodophenyl pentadecanoic acid (BMIPP) and I-123-metaiodobenzylguanidine (MIBG) cardiac scintigraphy. Tl-201 studies showed normal uptake in the left ventricle indicating normal blood perfusion. I-123 BMIPP and I-123 MIBG showed reduced uptake in the inferior segment of the myocardium, indicating impairment of fatty acid metabolism and sympathetic abnormalities.

CD36 genotype and long-chain fatty acid uptake in the heart

Homozygous or compound heterozygous mutation of the CD36 gene (CD36-/-) in humans results in severe defects of the uptake of long-chain fatty acids (LCFAs) in the heart. Because the effect of a single mutation of this gene (CD36+/-) on the LCFA uptake is not known, it was evaluated in 29 subjects with the CD36 wild-type gene (WT) (6 healthy subjects, 10 patients with heart disease), CD36+/- (4 healthy subjects, 5 patients) and CD36-/- (4 patients). The CD36 genotype was identified in the coding region of genomic DNA, and the expression of CD36 protein was examined by flow cytometry after staining with monoclonal anti-CD36 antibody. The LCFA uptake in the heart was assessed as the radioactivity accumulation ratio of heart to mediastinum after intravenous administration of iodine-123 15-(p-iodophenyl)-3-R, S-methylpentadecanoic acid (H/M ratio). The H/M ratios in WT, CD36+/- and CD36-/- were 2.28 +/- 0.10, 1.90 +/- 0.06 and 1.40 +/- 0.11, respectively (p < 0.0001, among groups). The H/M ratio between healthy subjects and patients with heart disease for WT and CD36+/- did not differ significantly (ie, those of WT and CD36+/- in healthy subjects and patients were 2.29 +/- 0.08 vs 2.27 +/- 0.12 and 1.90+/- 0.07 vs 1.89 +/- 0.05, respectively). Not only CD36-/- but also CD36+/- resulted in a significant reduction of the LCFA uptake in the heart independent of heart disease, suggesting genotype dependency and that CD36 might be a fundamental determinant of myocardial LCFA uptake.