Prognostic value of impaired myocardial fatty acid uptake in patients with acute myocardial infarction

Microvascular obstruction on delayed enhancement cardiac magnetic resonance imaging after acute myocardial infarction, compared with myocardial (201)Tl and (123)I-BMIPP dual SPECT findings

BACKGROUND

The hypo-enhanced regions within the hyper-enhanced infarct areas detected by cardiac magnetic resonance (CMR) imaging reflect microvascular obstruction (MO) after acute myocardial infarction (AMI). The combined myocardial thallium-201 ((201)Tl)/iodine-123-15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid ((123)I-BMIPP) dual single-photon emission computed tomography (SPECT) is a useful tool for detecting myocardial reversibility after AMI. We evaluated whether MO could be an early predictor of irreversible myocardial damage in comparison with (201)Tl and (123)I-BMIPP dual SPECT findings in AMI patients.

METHODS

Sixty-two patients with initial AMI who successfully underwent coronary revascularization were enrolled. MO was defined by CMR imaging. Patients were divided into 2 groups as follows: MO group (n=32) and non-MO group (n=30). Scintigraphic defect scores were calculated using a 17-segment model with a 5-point scoring system. The mismatch score (MMS) was calculated as follows: the total sum of (Σ) (123)I-BMIPP defect score minus Σ(201)Tl defect score. The percentage mismatch score (%MMS) was calculated as follows: MMS/(Σ(123)I-BMIPP score)×100 (%).

RESULTS

The percentage infarct size (%IS) was significantly greater in the MO group than in the non-MO group (32.2±13.8% vs. 18.3±12.1%, p<0.001). The %MMS significantly correlated with the %IS and the percentage MO (r=-0.26, p=0.03; r=-0.45, p<0.001, respectively). The %MMS was significantly greater in the non-MO group than in the MO group (45.4±42.4% vs. 13.3±28.0%, p=0.001), and was an independent predictor for MO (OR 0.97, 95%CI 0.94-0.99, p=0.02).

CONCLUSIONS

Our results reconfirm that, in comparison with myocardial dual scintigraphy, MO is an important structural abnormality. CMR imaging is useful for the early detection of irreversible myocardial damage after AMI.

Prognostic value of automated SPECT scoring system for coronary artery disease in stress myocardial perfusion and fatty acid metabolism imaging

Quantitative SPECT analysis contributes to the diagnostic and prognostic assessment of coronary artery disease. A novel automated scoring system (heart score view) can provide identical quantitative information to that determined by expert visual analysis. The aim of the present study is to evaluate the prognostic value of the automated SPECT scoring system when applied to stress thallium and resting beta-methyl-iodophenyl pentadecanoic acid (BMIPP) SPECT images. After a preliminary validation of the automated system by comparison with expert visual analyses, outcome data from 151 consecutive patients with suspected or known coronary artery disease without prior myocardial infarction were analyzed using automated SPECT scores on stress thallium and resting BMIPP images. The software quantified abnormalities as summed stress (SSS), summed rest and summed difference scores for stress thallium and as summed BMIPP scores (SBS). Cardiac events occurred over a period of 48 months in 29 (19.2%) patients with diabetes mellitus, a lower left ventricular ejection fraction (LVEF) and more abnormal scores for thallium and BMIPP. Multivariate predictors of all cardiac events included diabetes mellitus and thallium SSS. The global Chi-square value was significantly increased when SSS was added to the clinical information (diabetes mellitus and LVEF). Negative predictive values of thallium SSS and SBS were almost identical at 84% for all cardiac events and 98% for hard cardiac events. Automatically quantified perfusion and BMIPP scores are related to cardiac events and these values can improve the risk stratification of coronary patients particularly when stress thallium imaging is combined with clinical information.

Effects of fatty acids on human serum albumin binding centers

Albumin is a carrier of nonesterified long-chain fatty acids and many other ligands. The status of its binding centers was studied for various proportions of nonesterified long-chain fatty acids and albumin as exemplified by palmitic acid. The status of the binding center was tested by recording K-35 probe fluorescence decay in the subnanosecond band. This method showed the work of three types of centers. Palmitic acid enhanced binding activity of all centers, though to a different degree: if the palmitic acid/albumin proportion increased to 2-3, the probe binding to type 1 centers (located in the drug center I region) increased 1.5 times, while binding to type 3 centers increased more than 3-fold. Modification of these centers by nonesterified long-chain fatty acids was similar in the isolated human albumin preparation and in diluted blood serum. Hence, K-35 probe showed the actual status of various albumin centers, their binding capacity depending to a different measure on the fatty acid charge of albumin.

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.

Novel iodinated tracers, MIBG and BMIPP, for nuclear cardiology

With the rapid growth of molecular biology, in vivo imaging of such molecular process (i.e., molecular imaging) has been well developed. The molecular imaging has been focused on justifying advanced treatments and for assessing the treatment effects. Most of molecular imaging has been developed using PET camera and suitable PET radiopharmaceuticals. However, this technique cannot be widely available and we need alternative approach. ¹²³I-labeled compounds have been also suitable for molecular imaging using single-photon computed tomography (SPECT) ¹²³I-labeled meta-iodobenzylguanidine (MIBG) has been used for assessing severity of heart failure and prognosis. In addition, it has a potential role to predict fatal arrhythmia, particularly for those who had and are planned to receive implantable cardioverter-defibrillator treatment. ¹²³I-beta-methyl-iodophenylpentadecanoic acid (BMIPP) plays an important role for identifying ischemia at rest, based on the unique capability to represent persistent metabolic alteration after recovery of ischemia, so called ischemic memory. Since BMIPP abnormalities may represent severe ischemia or jeopardized myocardium, it may permit risk analysis in CAD patients, particularly for those with chronic kidney disease and/or hemodialysis patients. This review will discuss about recent development of these important iodinated compounds.

The washout rate of (123)I-BMIPP and the evolution of left ventricular function in patients with successfully reperfused ST-segment elevation myocardial infarction: comparisons with the echocardiography

The evolution of the oxidative metabolism of (11)C acetate parallels the recovery of left ventricular(LV) contraction following acute myocardial infarction(AMI). This study was designed to unravel, for the first time, the impact of the global washout rate(WR) of (123)I-beta-methyl-p-iodophenylpentadecanoic acid (BMIPP) on the recovery of LV function followingAMI, as evidenced from conventional echocardiography.Twenty consecutive patients (age: 58 +/- 13 years; 16 males and 4 females) with ST-segment elevation myocardial infarction (STEMI) were enrolled and all of them underwent successful percutaneous coronary intervention (PCI). (123)I-BMIPP cardiac scintigraphy was performed at 7 +/- 3 days after admission. The WR was calculated from the polar map and the regional BMIPP defect score was calculated using a 17 segment model. Echocardiography was performed within 24 h of admission and at 3 months to record the ejection fraction (EF), the wall motion score index (WMSI), the ratio of the mitralinflow velocity to the early diastolic velocity (E/E0)and the myocardial performance index (MPI). The mean global WR of the BMIPP was 22.12 +/- 7.22%, and it was significantly correlated with the improvement of the WMSI (r = 0.61, P\0.004). However,the relative changes of the EF, E/E0 and MPI were not correlated with the WR. The BMIPP defect score (18 +/- 10) was significantly correlated with the WMSI on admission (r = 0.74, P = 0.0002), but the defect score was not correlated with the relative changes of any of the echocardiographic parameters. We proved that the WR of the BMIPP is a promising indicator of improvement of the LV wall motion (WMSI) following ST-segment elevation myocardial infarction and successful reperfusion.

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.

123I-BMIPP delayed scintigraphic imaging in patients with chronic heart failure

OBJECTIVE

The objective of the present study was to clarify the ability of 123I-beta-methyl-iodophenylpentadecanoic acid (123I-BMIPP) to evaluate the heart-to-mediastinum (H/M) ratio and myocardial global washout rate (WR) in patients with chronic heart failure (CHF).

METHODS

The severity of CHF was evaluated on the basis of the New York Heart Association (NYHA) classification. Twenty patients with CHF (13 with idiopathic dilated cardiomyopathy and 7 with ischemic cardiomyopathy) and 11 age-matched controls underwent myocardial radionuclide imaging. Scintigraphic images were obtained from each participant at the early (30 min following radio-isotope injection) and late (4 h) phases using 123I-BMIPP. The H/M ratio and WR were calculated from planar images. Concentrations of plasma brain natriuretic peptide (BNP) were measured prior to the scintigraphic study.

RESULTS

The 123I-BMIPP uptake of early H/M and global WR did not significantly differ among groups, but uptake of delayed H/M was significantly lower in patients with NYHA class III than in controls (control 2.47 +/- 0.39; class III 1.78 +/- 0.28, P < 0.05). The uptake of delayed H/M and global WR correlated with plasma log BNP in all participants (r = -0.38, P < 0.05; 0.43, P < 0.05, respectively).

CONCLUSIONS

These data suggest that 123I-BMIPP uptake of delayed H/M enhances the image of CHF severity. The myocardial WR of 123I-BMIPP also effectively depicted the severity of CHF.

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.

Delayed recovery of fatty acid metabolism after transient myocardial ischemia: a potential imaging target for "ischemic memory"

The myocardium preferentially oxidizes free fatty acids for energy production. However, the dependency of this metabolic pathway on oxygen makes this process vulnerable to ischemia. The energy requirements of the myocardium are subsequently met by the oxidation of carbohydrates, particularly glucose. Recovery of fatty acid metabolism lags behind restoration of perfusion, resulting in the phenomenon of metabolic stunning. This decrease of fatty acid utilization following ischemia can be imaged with fatty acid radiotracers, particularly beta-Methyl-p-(123)I-iodophenyl pentadecanoic acid (BMIPP), which demonstrates markedly limited metabolism via beta-oxidation, resulting in prolonged retention in the cardiomyocyte. Thus, in patients presenting with chest pain and no prior myocardial infarction, abnormal BMIPP uptake at rest reflects metabolic alteration caused by the preceding ischemia, also termed ischemic memory.

The significance of 123I-BMIPP delayed scintigraphic imaging in cardiac patients

BACKGROUND

Earlier studies have not fully investigated the significance of radionuclide planar imaging in cardiac patients using the fatty acid analogue 123I-beta-methyl-iodophenylpentadecanoic acid (123I-BMIPP).

OBJECTIVES

This study was to clarify the effectiveness of 123I-BMIPP in assessing the heart-to-mediastinum ratio (H/M) and myocardial washout rate (WR) in patients with heart disease.

METHODS

Myocardial 123I-BMIPP imaging was performed in 33 patients (20 with chronic heart failure [CHF] and 13 with stable angina pectoris [AP]) and 11 control subjects. Myocardial 123I-BMIPP planner images were obtained 30 min (early image) and 4 h (delayed image) after tracer injection. The left ventricular ejection fraction (LVEF) was measured by quantitative gated single photon emission computed tomography. The concentration of plasma brain natriuretic peptide (BNP) was measured before the scintigraphic study.

RESULTS

(1) Delayed H/M was much lower in CHF than in AP (1.93 +/- 0.37 vs. 2.21 +/- 0.38, p < 0.05) and controls (vs. 2.47 +/- 0.38, p < 0.001). (2) The WR in CHF and AP were higher than the WR in controls (39.8 +/- 12.7% and 38.7 +/- 11.1 vs. 27.9 +/- 10.2%, p < 0.01 and p < 0.05, respectively). (3) In all subjects, LVEF was correlated with delayed H/M (r = 0.39, p < 0.01). And, the BNP was correlated with both the WR (r = 0.36, p < 0.05) and delayed H/M (r = - 0.29, p = 0.05).

CONCLUSION

These data strongly suggest that the delayed H/M and myocardial WR of 123I-BMIPP enhances the assessment of the myocardial fatty acid metabolism disorders in patients with heart disease in both masked and unmasked conditions.

Evaluation of no-reflow phenomenon using 201TlCl/123I-BMIPP dual-isotope myocardial SPECT

OBJECTIVES

We assessed the usefulness of (201)thallous chloride (TlCl)/(123)I-beta-methyl iodophenyl pentadecanoic acid (BMIPP) dual-isotope single-photon emission computed tomography (SPECT) to identify the "no-reflow phenomenon," defined as inadequate myocardial perfusion through a given segment of the coronary circulation without angiographic evidence of mechanical vessel obstruction.

METHODS

(201)TlCl/(123)I-BMIPP SPECT was performed in 73 patients within approximately 1 week of initial acute myocardial infarction (AMI) after percutaneous coronary intervention (PCI). We divided the left ventricular myocardium into 17 segments on each SPECT image and scored tracer accumulation in each segment with a five-point scoring system according to the American Heart Association criteria. Total severity scores were calculated by summing the scores for all 17 segments. The mismatch ratio between myocardial perfusion and metabolism was derived from the (201)TlCl and (123)I-BMIPP total severity scores: mismatch ratio=((123)I-BMIPP total severity score -(201)TlCl total severity score)/(123)I-BMIPP total severity score. Patients were classified according to Thrombolysis in Myocardial Infarction (TIMI) flow grade as having TIMI reflow grade 0-I (TIMI 0-I reflow group; n=11), II (TIMI II reflow group; n=17) and III (TIMI III reflow group; n=45). The TIMI III reflow group was subdivided into two groups with (201)TlCl total severity scores of < or =13 (TIMI III (A) reflow group; n=36) and > or =14 (TIMI III (B) reflow group; n=9), respectively.

RESULTS

The mismatch ratios in the TIMI II (0.4 +/- 0.3) and TIMI III (0.4 +/- 0.2) reflow groups were significantly higher than that in the TIMI 0-1 reflow group (0.1 +/- 0.1, p<0.05). Although coronary angiography revealed TIMI III flow after reperfusion, the mismatch ratios in the TIMI III (B) reflow group (0.2 +/- 0.1) and in the TIMI 0-I reflow group (0.1 +/- 0.1) were significantly lower than that in the TIMI III (A) reflow group (0.4 +/- 0.2, p<0.01), reflecting noneffective recanalization (so called no-reflow phenomenon).

CONCLUSION

(201)TlCl/(123)I-BMIPP dual-isotope myocardial SPECT reveals the biochemical degree of the no-reflow phenomenon, whereas coronary angiography shows recanalized vascular flow only. Dual-isotope myocardial SPECT might be useful for evaluating reperfusion therapy.

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.

Early positive biomarker in relation to myocardial necrosis and impaired fatty acid metabolism in patients presenting with acute chest pain at an emergency room

BACKGROUND

Measurement of circulating biomarkers has enabled early diagnosis and risk assessment of acute coronary syndrome. This study sought diagnostic values of the first single-point data of biomarkers obtained soon after patient arrival by comparing with scintigraphically quantified myocardial injury in patients presenting with acute chest pain at an emergency room.

METHODS AND RESULTS

Serial blood samples were taken soon after arrival in an emergency department in 74 patients with suspected acute coronary syndrome to quantify blood levels of troponin-T (TnT), heart-type fatty acid-binding protein (H-FABP), myocardial-bound creatine kinase (CK-MB), and myoglobin. Myocardial perfusion and metabolic defects were scintigraphically quantified. The first single-point data had high positive predictive values for detecting the defects (80-100%) but low negative predictive values (15-41%). CK-MB and TnT had higher specificities (73-100%) but significantly lower positive rates (22-27%) than the others (61-68%), resulting in greater sensitivities of H-FABP and myoglobin (75-80%) than those of CK-MB and TnT (29-35%). Among biomarkers, TnT peak concentrations most closely correlated with scintigraphic abnormalities.

CONCLUSION

H-FABP can contribute to early detection of myocardial injury and TnT is most likely to correlate with injured myocardial mass. The differential features of biomarkers are complementary in patients with acute chest pain presenting at an emergency room.

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.

Prognostic value of fatty acid imaging in patients with angina pectoris without prior myocardial infarction: comparison with stress thallium imaging

A fatty acid analogue, 123I-labelled beta-methyl iodophenyl pentadecanoic acid (BMIPP), has been used to identify ischaemic and metabolically impaired myocardium. However, the prognostic value of BMIPP imaging, particularly in relation to stress myocardial perfusion imaging, remains unclear. Data from 167 consecutive patients with angina pectoris but without prior myocardial infarction (MI) who had undergone both BMIPP and stress 201Tl (sTL) imaging were analysed. Tracer uptake was graded using a 13-segment, 4-point scoring model. Patients were followed up for 48 months with primary end points (cardiac death, non-fatal MI) as hard cardiac events and with secondary end points (late revascularisation, recurrent angina and heart failure) as soft events. For overall cardiac events (5 hard and 29 soft events), Kaplan-Meier analysis revealed significantly lower event rates in subgroups with normal BMIPP uptake, a summed difference score of sTL (SDS) of <3 or absence of diabetes mellitus when compared to each counterpart. Multivariate Cox's analysis revealed reduced BMIPP uptake, SDS > or =3, diabetes and reduced ejection fraction to be significant predictors. Negative predictive values of normal BMIPP and SDS <3 for all events were 91% and 84%, respectively. No hard event occurred in 66 patients with normal BMIPP uptake, whereas two patients with SDS <3 but impaired BMIPP uptake had hard events. In conclusion, normal BMIPP imaging is an excellent prognostic sign, independently of stress myocardial perfusion imaging, in patients with angina pectoris without prior MI.

Incremental predictive value of myocardial scintigraphy with 123I-BMIPP in patients with acute myocardial infarction treated with primary percutaneous coronary intervention

PURPOSE

It is unclear whether 123I-labelled beta-methyl iodophenyl pentadecanoic acid (123I-BMIPP) myocardial scintigraphy adds further predictive value for future cardiac events compared with the variables obtained during cardiac catheterisation in patients with acute myocardial infarction (AMI) treated with primary percutaneous coronary intervention (PCI). We therefore investigated whether 123I-BMIPP imaging in patients with AMI treated by primary PCI was useful in predicting future cardiac events.

METHODS

One hundred and fifty-nine patients with AMI who were treated with primary PCI and underwent left ventriculography (LVG) on admission underwent 201Tl and 123I-BMIPP myocardial scintigraphy. Scintigrams were visually classified, and the total defect score (TDS) was calculated. Major adverse cardiac events (MACE) were defined as cardiac death including sudden death, congestive heart failure and recurrence of acute coronary syndrome. Patients were followed up for a mean of 34.5 months (12-63 months).

RESULTS

Twenty-six patients had MACE. Kaplan-Meier analysis indicated that patients with the top 50% of 123I-BMIPP TDSs had a significantly higher rate of MACE (P=0.007). Patients with mismatch between 201Tl and 123I-BMIPP images also had significantly more MACE (P=0.02). In the prediction of MACE, the global chi-square value was 5.2 (P=0.001) based on LVEF (<45%) and the number of diseased vessels (two or three). Adding 123I-BMIPP TDS and the mismatch improved the global chi-square value (chi2=7.2)

CONCLUSION

Myocardial scintigraphy using 201Tl and 123I-BMIPP predicts future cardiac events in patients with AMI treated with primary PCI, and provides additional predictive value compared with the variables obtained with cardiac catheterisation alone.

Usefulness of Simultaneous Evaluations of Contractile Reserve, Perfusion, and Metabolism During Dobutamine Stress for Predicting Wall Motion Reversibility (Myocardial Stunning) After Successful PTCA

The optimal diagnostic approaches using contractile reserve, perfusion, and free fatty acid metabolism together for identifying myocardial stunning after reperfusion have not been clarified in the clinical setting. We investigated the usefulness of simultaneous evaluation of these parameters during myocardial stunning to predict the functional recovery in infarct-related myocardium after reperfusion. In 43 patients (60.7 +/- 10.4 years) with successful coronary angioplasty early after a first myocardial infarction, low-dose (5 to 10 microg/kg/min) dobutamine stress thallium-201/iodine-123 beta-methyl-iodophenyl pentadecanoic acid (BMIPP) dual-isotope single photon emission computed tomography was performed with echocardiography in the acute phase within 1 week after reperfusion. Regional wall motion and the uptake of each tracer were obtained simultaneously in the infarct-related segments. In 93 segments with dyssynergy in the acute phase after reperfusion, the sensitivity, specificity, and accuracy using contractile reserve for predicting the final functional recovery in the chronic phase more than 3 months after PTCA were 81.3%, 67.2%, and 72%, respectively. More accurate predictions were obtained by simultaneous measurements of thallium-201 and BMIPP uptakes (93.8%, 66.7%, and 79.4%, respectively). The final functional recovery in the stunned myocardium after early reperfusion following acute myocardial infarction was predicted more accurately by simultaneous evaluation of these parameters at dobutamine stress testing.

Lipid metabolism in the heart--contribution of BMIPP to the diseased heart

Lipid contributes greatly in cardiac metabolism to produce high energy ATPs, and is suggested to be related to the progression and deterioration of heart disease. It is fortunate that the I-123-betamethyliodophenylpentadecanoic acid (BMIPP) imaging technique is now available in determining heart condition, but we must be cautious about the interpretation of images obtained with this new tracer. From the uptake of BMIPP into the cell to breakdown and catabolism of it, there exist so many critical enzymatical pathways relating to the modification of BMIPP imaging. In clinical evaluation, the image will be translated as the integral effects of these pathways. In other words, we must be aware of these critical pathways regulating lipid metabolism and modifying factors in order to correctly understand BMIPP imaging. Lipid transport is affected by the albumin/FFA ratio in the blood, and extraction with membrane transporter proteins. Fatty acid binding protein (FABP) in the cytosole will play an important role in regulating lipid flux and following metabolism. Lipid will be utilized either for oxidation, triglyceride or phospholipid formation. For oxidation, carnitine palmitoil transferase is the key enzyme for the entrance of lipid into mitochondria, and oxidative enzymes such as acyl CoA dehydrogenase (MCAD, LCAD, HAD) will determine lipid use for the TCA cycle. ATPs produced in the mitochondria again limit the TG store. It is well known that BMIPP imaging completely changes in the ischemic condition, and is also shown that lipid metabolical regulation completely differs from normal in the very early phase of cardiac hypertrophy. In the process of deteriorating heart failure, metabolical switching of lipid with glucose will take place. In such a different heart disease conditions, it is clear that lipid metabolical regulation, including many lipid enzymes, works differently from in the healthy condition. These lipid enzymes are regulated by nuclear factor peroxisome proliferator-activated receptors (PPAR) just like a conductor of an orchestra. Most of the regulating mechanisms of the PPAR are still unknown, but reduction of this nuclear factor is shown in the process of decompensated heart failure. This review is based by mostly on our fundamental and Japanese clinical data. BMIPP has been used clinically in abundant cases in Japan. In such situations, further correct information on lipid metabolism, including BMIPP, will contribute to the understanding of deteriorating heart disease and its prognosis.