Peak systolic blood pressure in exercise testing is associated with scintigraphic severity of myocardial ischemia in patients with exercise-induced ST-segment depression.

Some electrocardiographic variables, including the degree of maximal ST-segment depression (STD), may not necessarily indicate the severity of exercise-induced myocardial ischemia. The present study examined whether maximal STD correlates with the severity and extent of exercise-induced myocardial ischemia, as assessed by thallium-201 (201Tl) imaging, and which parameter of exercise testing reflects scintigraphic severity and extent in 270 patients who had a 1 mm or greater horizontal or down-sloping STD on exercise 201Tl imaging. The scintigraphic severity and extent of exercise-induced ischemia was assessed and correlated with maximal STD, number of positive leads, workload, peak heart rate, peak systolic blood pressure (SBP), rate-pressure product, chest pain and the Duke treadmill score. Most of the scintigraphic markers of the severity and extent of ischemia had significant but weak correlation with all of those parameters. Multivariate analysis demonstrated that peak SBP and the Duke treadmill score (chest pain in only simple variables model) correlated independently with scintigraphic severity and extent of ischemia. Furthermore, most of the patients with a peak SBP of 200 mmHg or more had milder and less extensive ischemia. In patients with exercise-induced STD, the scintigraphic severity and extent of ischemia may be estimated by peak SBP and the Duke treadmill score.

Exercise myocardial perfusion scintigraphy is useful for evaluating myocardial ischemia even in the elderly.

Pharmacologic stress testing is recommended to elderly patients as a valuable alternative to exercise testing. We examined whether exercise testing is as useful for evaluating myocardial ischemia in the elderly as in the young. The consecutive 1,508 patients who underwent exercise 201Tl single-photon emission computed tomography (SPECT) were divided into six age groups: 6-29 years (n = 56), 30-44 (n = 143), 45-54 (n = 311), 55-64 (n = 498), 65-74 (n = 402), and 75-88 (n = 98). Both heart rate and rate-pressure product at peak exercise were significantly lower in patients aged 75-88 than in the other five groups. The frequency of ischemic ST depression was higher in patients aged 75-88 than in those aged 6-74, although the difference was not significant. Moreover, the frequency of 201Tl transient defect was significantly higher in patients aged 75-88 than in those aged 6-74. On the other hand, the sensitivity of ischemic ST depression for 201Tl transient defect was similar among the six groups, but the specificity was significantly lower in patients aged 75-88 than in those aged 6-74. In conclusion, exercise 201Tl SPECT is useful for evaluating myocardial ischemia even in the elderly, but exercise electrocardiography has limitations such as lower specificity in the elderly than 201Tl SPECT.

[Strategy for primary prevention of coronary heart disease based on results of health check-up].

To investigate one of the strategies for effective primary prevention of coronary heart disease (CHD) in employees, the future morbidity of CHD was predicted from the results of an annual health check-up. The decrease in morbidity by measures against coronary risk factors was estimated with simulations. By a CHD risk prediction algorithm based on the Framingham Study, the 10-yr incidence of CHD was predicted in 6,444 male employees of a manufacturing company according to the results of a health check-up in 1998: age, total cholesterol (TC), HDL-cholesterol (HDL-C), blood pressure (BP), diabetes mellitus, and smoking habit. The decrease in CHD incidence obtained by a decrease in TC, increase in HDL-C, decrease in BP, control of diabetes mellitus, or quitting the smoking habit was estimated with simulations by means of the algorithm. The mean +/- SD in 6,444 employees was 45 +/- 11 yr for age; 121 +/- 16 and 79 +/- 10 mmHg for systolic and diastolic BP, respectively; 193 +/- 34, 53 +/- 13, and 98 +/- 18 mg/dl for TC, HDL-C, and fasting blood sugar, respectively; 4.80 +/- 0.58% for HbA1c; and 44% for the frequency of the smoking habit. Among 6,444 males, 455 (7.1%) were predicted to suffer from CHD for 10 yr ahead. If TC was decreased to less than 200 mg/dl in all 2,614 males (N) with TC > or = 200 mg/dl, the decrease (D) in the predicted number of employees with CHD was 64; namely, a reduction of TC to less than 200 mg/dl in 41 males (N/D) with TC > or = 200 mg/dl was estimated to decrease the number of CHD patients by one. Similarly, the D and N/D were 38 and 35 for reduction in BP to less than 140/90 mmHg; 20 and 17 for control of diabetes mellitus; and 90 and 32 for quitting the smoking habit, respectively. A measure against diabetes mellitus was the most effective in respect of N/D, but the predicted total reduction was small (D = 20). On the other hand, a measure against the smoking habit was estimated to have a relatively small N/D as well as the largest D. In 5,386 employees with at least one of the risk factors of TC > or = 200 mg/dl, HDL-C < 45 mg/dl, BP > or = 130/85 mmHg, diabetes mellitus, and the smoking habit, the normalization of all risk factors was estimated to decrease by 230 CHD patients (D = 230, N/D = 23). These results suggest that the strategy for effective primary prevention of CHD in employees of a company should include at first, quitting the smoking habit supported by total prohibition of smoking within company facilities, followed by measures against hyperlipidemia, hypertension and diabetes mellitus.

Cardiac autonomic neuropathy in patients with chronic renal failure on hemodialysis.

To characterize uremic cardiac autonomic neuropathy, we measured plasma catecholamines, analyzed the 24-hour heart rate variability (HRV), and acquired serial images with (123)I-metaiodobenzylguanidine (MIBG) in 44 patients with chronic renal failure on hemodialysis and in 14 controls. Time-domain measures were calculated using the Marquette HRV program. MIBG clearance rates from the heart and lung were evaluated on planar images, and the regional MIBG uptake in the left ventricular myocardium was evaluated with single-photon emission computed tomography. Compared with controls, plasma dopamine and norepinephrine levels were elevated (p < 0.001 and p = 0.03, respectively), and all the time-domain measures of HRV were reduced in the patients (p < 0.001). The MIBG clearance rate from the heart was higher (p < 0.001), that from the lung was lower (p < 0.001), and the myocardial MIBG distribution was more heterogeneous in patients than in controls (total uptake score p

Is abnormal iodine-123-MIBG kinetics associated with left ventricular dysfunction in patients with diabetes mellitus?

BACKGROUND: Although autonomic neuropathy is frequently recognized in patients with diabetes mellitus, it is uncertain whether cardiac sympathetic neuropathy may play a role in the development of diabetic cardiomyopathy. METHODS AND RESULTS: In 10 control subjects and 61 patients with diabetes mellitus who did not have coronary artery disease, cardiac sympathetic function and left ventricular ejection fraction (LVEF) were evaluated by using iodine-123-metaiodobenzylguanidine (MIBG) imaging and echocardiography, respectively. Dynamic acquisitions and planar images obtained 15 and 150 minutes after injection were used as a means of measuring early and late myocardial uptake and clearance rates of MIBG from the heart. Eight patients with an LVEF less than 50% demonstrated a lower late myocardial MIBG uptake (0.0043% +/- 0.0017% vs. 0.0024% +/- 0.0009%/pixel, P = .002) and a higher clearance rate (22.9% +/- 17.7% vs. 49.3% +/- 12.2%, P<.0001) than the 53 patients with an LVEF of 50% or greater, although the age, sex, type of diabetes mellitus, and frequency of neuropathy, retinopathy, and nephropathy were not significantly different between the 2 subgroups. The LVEF correlated weakly but significantly with early and late myocardial uptake and clearance rate (r = 0.277, P = .03; r = 0.421, P = .001; r = 0.382, P = .002; respectively) in patients with diabetes mellitus. CONCLUSION: Marked MIBG abnormalities are associated with left ventricular dysfunction in patients with diabetes mellitus. However, long-term follow-up of patients with diabetes mellitus who have marked MIBG abnormalities and normal LVEF will be required to determine whether these patients would demonstrate systolic dysfunction earlier than patients without an MIBG abnormality.

Syncope caused by nonsteroidal anti-inflammatory drugs and angiotensin-converting enzyme inhibitors.

A 85-year-old woman with diabetes mellitus and prior myocardial infarction was transferred to the emergency room with loss of consciousness due to marked bradycardia caused by hyperkalemia. The T wave during right ventricular pacing was tall and tent-shaped while the concentration of serum potassium was high, and its amplitude during pacing was decreased after correction of the serum potassium level. Simultaneously with the correction, normal sinus rhythm was restored. The cause of hyperkalemia was considered to be several doses of loxoprofen, a nonsteroidal anti-inflammatory drug (NSAID), prescribed for her lumbago by an orthopedic specialist, in addition to the long-term intake of imidapril, an angiotensin-converting enzyme inhibitor (ACEI), prescribed for her hypertension by a cardiologist. This case warns physicians that the combination of NSAID and ACEI can produce serious side effects in aged patients who frequently suffer from hypertension, diabetes mellitus, ischemic heart disease, and degenerative joint disease.

Diabetic cardiac autonomic dysfunction: parasympathetic versus sympathetic.

BACKGROUND: Diabetic cardiac autonomic dysfunction often causes lethal arrhythmia and sudden cardiac death. 123I-Metaiodobenzylguanidine (MIBG) can evaluate cardiac sympathetic dysfunction, and analysis of heart rate variability (HRV) can reflect cardiac parasympathetic activity. We examined whether cardiac parasympathetic dysfunction assessed by HRV may correlate with sympathetic dysfunction assessed by MIBG in diabetic patients. METHODS AND RESULTS: In 24-hour electrocardiography, we analyzed 4 HRV parameters: high-frequency power (HF), HF in the early morning (EMHF), rMSSD and pNN50. MIBG planar images and SPECT were obtained 15 minutes (early) and 150 minutes (late) after injection and the heart washout rate was calculated. The defect score in 9 left ventricular regions was scored on a 4 point scale (0 = normal approximately 3 = severe defect). In 20 selected diabetic patients without congestive heart failure, coronary artery disease and renal failure, parasympathetic HRV parameters had a negative correlation with the sum of defect scores (DS) in the late images (R = -0.47 approximately -0.59, p < 0.05) and some parameters had a negative correlation with the washout rate (R = -0.50 approximately -0.55, p < 0.05). In a total of 64 diabetic patients also, these parameters had a negative correlation with late DS (R = -0.28 approximately -0.35, p < 0.05) and early DS (R = -0.27 approximately -0.32, p < 0.05). CONCLUSIONS: The progress of diabetic cardiac parasympathetic dysfunction may parallel the sympathetic one.

Usefulness of measurement of plasma atrial natriuretic peptide levels in exercise testing of patients with coronary heart disease.

Atrial natriuretic peptide secretion on exercise testing may be exaggerated by left ventricular dysfunction due to multivessel coronary disease rather than by scintigraphically detectable myocardial ischemia. The measurement of plasma atrial natriuretic peptide levels during exercise test may provide additional information regarding the severity of coronary heart disease.

Cardiac sympathetic nervous system in early essential hypertension assessed by 123I-MIBG.

UNLABELLED: Sympathetic overactivity has been noted in various clinical stages of essential hypertension. The purpose of this study is to investigate 123I-metaiodobenzylguanidine (MIBG) uptake and washout in patients with borderline and mild hypertension. METHODS: To assess cardiac sympathetic function in essential hypertension, we performed 123I-MIBG cardiac imaging and echocardiography in 25 normotensive, 25 borderline hypertensive and 24 mildly hypertensive men. Age and body mass index were similar in the three groups. RESULTS: Regarding the echocardiographic variables, the left ventricular mass index (LVMI) was significantly higher in the mildly hypertensive group (125.6+/-28.6 g/m2) than in the normotensive (99.9+/-20.7 g/m2) and the borderline hypertensive (110.0+/-24.4 g/m2) groups (P < 0.001 and P < 0.05, respectively). Regarding the scintigraphic variables, the heart-to-mediastinum (H/M) ratio was significantly lower in the mildly hypertensive group (1.8+/-0.3) than in the normotensive (2.1+/-0.3) and the borderline hypertensive (2.1+/-0.2) groups. In contrast, the washout rate was significantly higher in the mildly hypertensive group (17.6%+/-10.8%) than in the normotensive (7.0%+/-4.9%) and the borderline (11.9%+/-8.9%) hypertensive groups (P< 0.001 and P< 0.02, respectively). In addition, the borderline hypertensive group had a significantly higher washout rate than the normotensive group (P < 0.05). MIBG washout rate had a strong positive correlation with LVMI (r = 0.77, P < 0.0001). In contrast, the H/M ratio had a weak negative correlation with LVMI (r = -0.40, P < 0.0006). CONCLUSION: During the course of establishment of essential hypertension, the washout rate becomes higher with the advance of hypertension and with the development of left ventricular hypertrophy. Thus, we suggest a strong relationship between cardiac sympathetic activity and the advance of hypertension at its early stages.

Effects of extrinsically elevated plasma norepinephrine concentration on myocardial 123I-MIBG kinetics in rats.

UNLABELLED: Rapid 123I-metaiodobenzylguanidine (MIBG) washout and high plasma norepinephrine (NE) levels are frequently observed in patients with congestive heart failure, and high plasma NE levels are not necessarily induced by increased cardiac NE spillover. The purpose of this study was to assess the effect of extrinsically elevated plasma NE levels on myocardial MIBG kinetics. METHODS: MIBG was injected into the femoral vein in 47 adult male Wister rats. In the first study, normal saline solution or NE (0.3, 1.0 and 3.0 microg/kg/min) was administered to each group of 6 or 7 rats continuously from 30 min before to 30 min after MIBG injection. In the second study, NE was administered at 3.0 microg/kg/min to each group of 7 rats continuously from 30 min before to 2 h after or from 30 to 60 min after MIBG injection, and NE was not administered to a control group of 7 rats. For 2 or 4 h after MIBG injection, scintigrams were acquired using a gamma camera with a pinhole collimator, after which myocardial MIBG uptake (percentage injected dose normalized for the difference in rat weight per tissue weight) was determined in isolated heart with a gamma counter. RESULTS: In the first study, the MIBG washout rate from the heart was significantly increased during high-dose NE infusion (1.0 and 3.0 microg/kg/min) compared with that during saline infusion, whereas the washout rate was not increased during low-dose NE infusion. In the second study, the MIBG washout rate from the heart during NE infusion was significantly increased compared with that of the control but was not increased during discontinuation of NE infusion. CONCLUSION: Extrinsically induced high levels of plasma NE may accelerate MIBG washout from the heart.

Treatment of hypertension on the basis of home measurements: a case report.

Should antihypertensive therapy be based on home blood-pressure monitoring in hypertensive patients with marked white-coat phenomenon? A 53-year-old hypertensive woman with marked white-coat phenomenon had been treated on the basis of blood pressure at home without measurements of clinic blood pressure for 5 years. The target of her treatment was changed to clinic blood pressure because of marked electrocardiographic abnormalities, which were subsequently normalized by the treatment given for the office hypertension. Thus, the experience of this case suggests that treatment of cases of hypertension with white-coat phenomenon should not be based only on home recordings.

Metaiodobenzylguanidine and heart rate variability in heart failure.

It is assumed that the low-frequency power (LF) of heart rate variability (HRV) increases with progress of congestive heart failure (CHF), therefore positively correlating with cardiac 123I-metaiodobenzylguanidine (MIBG) washout. It is demonstrated here that HRV, including normalized LF, correlated inversely with MIBG washout and positively with the ratio of heart-to-mediastinum MIBG activity in controls and CHF patients, whereas these correlations were not observed within CHF patients. Thus MIBG washout may increase and HRV including normalized LF may decrease with CHF, although the HRV and MIBG measures may not similarly change in proportion to the severity of the cardiac autonomic dysfunction in CHF.

Physiological fluctuation of the human left ventricle sympathetic nervous system assessed by iodine-123-MIBG.

UNLABELLED: It has been proposed that sympathetic nervous system pathophysiology is involved in the development of cardiovascular disorders. Since cardiac adrenergic activity has been difficult to assess in humans, physiological changes in the sympathetic nervous system in the human left ventricle remain unclear. METHODS: To determine if age and gender influence the sympathetic nervous function of the left ventricle, 300 angiographically normal subjects (170 men, 130 women; age range 40-79 yr) had 123I-metaiodobenzylguanidine (MIBG) cardiac imaging. Regional quantitative analysis of MIBG uptake and washout rate was performed. RESULTS: Men and women had prominent age-related decreases in MIBG uptake in the inferior and lateral walls (r2 = 0.34, p <0.0001 for both). Both genders had a significant positive correlation between regional washout rate and age in each region. In contrast to men, women had strong positive correlations in all regions (r2 = 0.54, p <0.0001 in the anterior wall, r2 = 0.56, p <0.0001 in the lateral wall and r2 = 0.44, p <0.0001 in the inferior wall). According to the decade-by-decade analysis of washout rate, women had a significantly lower washout than men under 50 yr in every region and a significantly higher washout in the lateral wall than men over 70 yr. CONCLUSION: The sympathetic nervous system in the human left ventricle showed age- and gender-related regional changes. The findings suggested that men have high sympathetic nerve activity from a younger age, and women have a progressive increase in sympathetic nerve activity with aging. These changes may contribute to the age and gender differences in the incidence and development of cardiac disorders.

[Usefulness of 123I-MIBG scintigraphy for prediction of effect of beta-blocker therapy in dilated cardiomyopathy].

To determine whether 123I-MIBG (MIBG) scintigraphy is useful for predicting the effect of beta-blocker therapy in patients with dilated cardiomyopathy (DCM), we studied MIBG scintigraphy in 11 controls and 9 patients with DCM before starting beta-blocker therapy. First, initial and delayed heart-to-mediastinum ratios (H/M ratio) of MIBG activity in patients with DCM were significantly lower than those in 11 controls, respectively (initial H/M; 1.8 +/- 0.3 vs. 2.1 +/- 0.3, p < 0.02, delayed H/M; 1.6 +/- 0.3 vs. 2.4 +/- 0.2, p < 0.0001), and MIBG washout rate from the heart was significantly higher in patients than in controls (washout rate; 33 +/- 7% vs. 22 +/- 4%, p < 0.0005). Second, beta-blocker therapy improved LVEF in 7 patients (improved group), while it resulted in deterioration of heart failure, followed by death in 2 patients (deteriorated group). Although initial and delayed H/M ratios in the improved group were not significantly different from those in the deteriorated group, respectively, MIBG washout rate was significantly higher in the deteriorated group than in the improved group (45 +/- 8% vs. 30 +/- 3%, p = 0.04). Our study suggests that DCM patients with markedly rapid MIBG clearance may be deteriorated by beta-blocker therapy. In contrast, there were no differences in LVEF and plasma norepinephrine between improved and deteriorated groups. In conclusion, 123I-MIBG scintigraphy is useful for predicting the effects of beta-blocker therapy in patients with DCM.

Comparison of effects of enalapril and nitrendipine on cardiac sympathetic nervous system in essential hypertension.

OBJECTIVES: The purpose of this study was to assess the effects of enalapril and nitrendipine on the cardiac sympathetic nervous system. BACKGROUND: Angiotensin-converting enzyme inhibitors and long-acting calcium channel blockers have been widely used in the treatment of cardiovascular diseases, in some of which sympathetic overactivity plays a major role in the pathophysiology and prognosis. However, little information is available on the effects of these drugs on the cardiac sympathetic nervous system. METHODS: 123I-metaiodobenzylguanidine (MIBG) cardiac imaging was performed before and 3 months after drug administration in 46 patients with mild essential hypertension. Twenty-two patients were treated with 5 to 10 mg of enalapril once a day, and the other 24 with 5 to 10 mg of nitrendipine once a day. For comparison, 20 normotensive subjects were also studied. RESULTS: There were no significant differences between the basal characteristics in the 2 hypertensive groups. In both hypertensive groups, both systolic and diastolic blood pressures were significantly reduced to similar levels after the 3-month drug treatment. Before the drug treatment, the 2 hypertensive groups had a significantly higher washout rate and lower MIBG uptake than the normotensive subjects. The heart-to-mediastinum ratio significantly increased (p < 0.0001), with decreased (p < 0.002) washout rate after drug treatment in the enalapril group, but with no significant changes in the nitrendipine group. CONCLUSION: Enalapril could suppress cardiac sympathetic activity and nitrendipine had no effect on it. The knowledge of antihypertensive drugs on the cardiac sympathetic nervous system appears to be helpful in selecting appropriate treatment in cardiovascular diseases.

Cardiac sympathetic neuropathy and effects of aldose reductase inhibitor in streptozotocin-induced diabetic rats.

UNLABELLED: Cardiac autonomic neuropathy can be a cause of sudden death in patients with diabetes mellitus. Clinical evaluation methods for diabetic cardiac sympathetic neuropathy have not been established. Using 125I-metaiodobenzylguanidine (MIBG) and streptozotocin (STZ)-induced diabetic rats, we evaluated cardiac sympathetic neuropathy and the effects of aldose reductase inhibitor (ARI). METHODS: Myocardial MIBG uptake was measured 4 hr after injection in the following groups: control rats, rats treated with insulin or ARI (epalrestat, 100 mg/kg/day) from immediately to 4 wk after STZ injection and rats treated with insulin or ARI from 4-8 wk. Myocardial MIBG distribution and norepinephrine content were evaluated in the control and diabetic rats with or without ARI therapy started immediately after STZ injection. RESULTS: Myocardial MIBG uptake was significantly lower in diabetic rats than in control rats; the reduction was marked in the subendocardial myocardium. Myocardial norepinephrine content was increased significantly in diabetic rats compared with control rats. Decreased MIBG uptake and increased norepinephrine content in diabetic myocardium were completely prevented by insulin therapy started immediately after STZ injection and partially, but significantly, by ARI administered from immediately after STZ injection. Heterogeneous MIBG distribution also disappeared with the ARI therapy. In contrast, diabetic rats treated with insulin or ARI therapy started 4 wk after STZ injection showed no improvement in MIBG uptake. CONCLUSION: These results suggest that MIBG abnormalities observed in diabetic rats may reflect diabetic cardiac sympathetic neuropathy independently of cardiomyopathy, nephropathy or coronary heart disease secondary to diabetes and that MIBG imaging may be useful for clinical assessment of cardiac sympathetic neuropathy.

Effects of cilazapril and verapamil on myocardial iodine-125-metaiodobenzylguanidine accumulation in cardiomyopathic BIO 53.58 hamsters.

UNLABELLED: Sympathetic nervous system activation is important in the pathophysiology of congestive heart failure. However, little about how the treatment for heart failure may influence myocardial sympathetic nervous activity has been established. In this study, we evaluated effects of cilazapril (CLZ) and verapamil (VER) on myocardial sympathetic nervous activity in cardiomyopathic BIO 53.58 hamsters using [125I]metaiodobenzylguanidine ([125I]MIBG). METHODS: We used BIO 53.58 hamsters aged 3, 6 and 10 mo and age-matched normal F1b hamsters. We divided BIO 53.58 hamsters into untreated, CLZ- and VER-treated groups. We measured myocardial [125I]MIBG uptakes and norepinephrine concentrations and evaluated the extent of fibrosis and the distribution of [125I]MIBG. RESULTS: The myocardial [125I]MIBG uptake was significantly lower in BIO 53.58 hamsters aged 6 and 10 mo than in age-matched F1b hamsters. Myocardial [125I]MIBG uptake was significantly correlated to myocardial norepinephrine concentration in BIO 53.58 hamsters. Myocardial [125I]MIBG uptake was significantly higher in both of the treated groups than in the untreated group. The extent of myocardial fibrosis was significantly lower in both of the treated groups than in the untreated group. The myocardial [125I]MIBG uptake showed a significant inverse correlation with the extent of fibrosis. Myocardial [125I]MIBG distribution was highly heterogeneous in the untreated BIO 53.58 hamsters, whereas it was homogeneous in the F1b hamsters aged 6 mo and the treated BIO 53.58 hamsters. CONCLUSION: In BIO 53.58 hamsters, myocardial [125I]MIBG uptake decreased with the progression of cardiomyopathy, and the decreased uptake was improved by treatment with CLZ and VER. Thus, myocardial [125I]MIBG uptake can reflect the effects of treatment on cardiomyopathy, as well as the progression of cardiomyopathy.

Iodine-123 metaiodobenzylguanidine cardiac imaging to identify and localize vasospastic angina without significant coronary artery narrowing.

OBJECTIVES: We assessed the ability of iodine-123 metaiodobenzylguanidine (MIBG) imaging to identify and localize coronary spasm and determined the most useful method of MIBG analysis in vasospastic angina without significant coronary narrowing. BACKGROUND: Various noninvasive methods have been used to detect vasospastic angina, but they are not very sensitive in patients with sporadic attacks. MIBG imaging has recently been proposed as a useful tool for detecting vasospastic angina. METHODS: Normal limits of both visual and quantitative analysis of two-dimensional polar maps (bull's-eyes) for MIBG imaging were at first established in 59 normal subjects. For optimal criteria of visual analysis, we established regional differences in abnormal MIBG defect scores. An abnormal region of the bull's-eye was defined as an area > 2 SD below normal. An abnormal regional washout rate was defined as < 0%. Using these criteria, we prospectively evaluated 104 patients with suspected vasospastic angina. Visual, bull's-eye and regional washout rate analyses were compared for overall detection of the disease and for individual vessel involvement. RESULTS: Overall sensitivity by these methods was 30%, 42% and 76%, respectively. Washout rate analysis showed a significantly higher sensitivity than the other two methods. Specificity was 78%, 72% and 87%, respectively. The sensitivity of detecting spasm-induced coronary artery with washout rate analysis was 82% for the left anterior descending (LAD), 76% for the right (RCA) and 69% for the circumflex (Cx) coronary arteries. The sensitivity of visual analysis was 29%, 15% and 35%, respectively; that for bull's-eye analysis was 34%, 54% and 41%, respectively. Washout rate analysis showed a significantly higher sensitivity for LAD spasm than for the other two methods and a higher sensitivity for RCA and Cx spasms than for visual analysis. CONCLUSIONS: Regional washout rate analysis of MIBG imaging is a highly accurate technique for determining the presence and location of coronary artery spasm.

Influence of blood substrate levels on myocardial kinetics of iodine-123-BMIPP.

UNLABELLED: To evaluate the influence of blood substrate levels on myocardial uptake of 123I-labeled beta-methyl-iodophenyl-pentadecanoic acid (BMIPP), we examined the correlation between myocardial BMIPP uptake and blood levels of free fatty acid (FFA), glucose, insulin, triglyceride and total cholesterol. METHODS: In 180 patients, venous blood samples were obtained, and the early and late myocardial uptakes (MU15 and MU150) were determined on planar images at 15 and 150 min after injection at rest, respectively, and the clearance rate of BMIPP from the myocardium was calculated. Dynamic SPECT with BMIPP, PET with [18F]fluoro-deoxyglucose and determination of myocardial carnitine contents were performed in 15, 1 and 3 patients, respectively. RESULTS: In the 180 patients, MU15 correlated with blood insulin (r = 0.22, p = 0.005) and FFA (r = -0.19, p = 0.02) levels, whereas MU150 did not correlate with blood levels of any variables that were measured (p > 0.05). The clearance rate correlated with blood insulin (r = 0.28, p < 0.001), glucose (r = 0.17, p = 0.03) and FFA (r = -0.40; p < 0.001) levels. The correlations were, however, weak, and five patients (2.8%) with no myocardial BMIPP uptake, all of whom had anterior myocardial infaction, had no characteristics regarding the blood substrate levels. Although dynamic SPECT demonstrated rapid myocardial extraction of BMIPP in 13 patients with myocardial BMIPP uptake, it demonstrated no myocardial BMIPP extraction in two patients with no myocardial BMIPP uptake. One of the five patients with no myocardial BMIPP uptake showed increased myocardial [18F]fluorodeoxyglucose uptake and decreased myocardial carnitine content. CONCLUSION: The influence of blood substrate levels on myocardial BMIPP uptake is not very significant, although high serum FFA levels may be associated with slow clearance of BMIPP from the myocardium. The complete absence of myocardial BMIPP uptake is not rare and may not be associated with changes in blood substrate levels or early back diffusion of BMIPP.