Comparison of uptake, oxidation and lipid distribution of 17-iodoheptadecanoic acid, 15-(p-iodophenyl)pentadecanoic acid and 15-(p-iodophenyl)-3,3-dimethylpentadecanoic acid in normal canine myocardium.

The kinetics of 17-[123I]iodoheptadecanoic acid (IHDA), 15-(p-[125I]iodophenyl)pentadecanoic acid (pIPPA) and 15-(p-[131I]iodophenyl)-3,3-dimethylpentadecanoic acid (DMIPPA) were investigated in normal canine myocardium. After simultaneous intravenous injection, myocardial biopsy specimens and samples of arterial blood were taken over 80 min. IHDA showed the highest myocardial uptake (995 +/- 248 dpm/mg.mCi versus pIPPA: 785 +/- 197 dpm/mg.mCi, ns) and the largest size of oxidation (74% +/- 4% versus pIPPA: 65% +/- 5%, p < 0.05). Myocardial activity of IHDA decreased with a half-time value of 11.2 min (pIPPA: 13.2 min). Phospholipids were the main lipid fraction into which IHDA was incorporated, whereas pIPPA was predominantly incorporated into triacylglycerols. DMIPPA myocardial activity remained constant during the assay period and instead of being oxidized, DMIPPA was mainly incorporated into triacylglycerols (55% +/- 12%). The myocardium-to-blood ratios of DMIPPA were greater than 10:1. The ratios at peak for IHDA and pIPPA were 4.1:1 and 3.9:1, respectively (both p < 0.0001 versus DMIPPA). In conclusion, differences have been found in the myocardial uptake, oxidation and lipid distribution of IHDA, pIPPA and DMIPPA. DMIPPA is a promising tracer for fatty acid uptake studies with single-photon emission computerized tomography because of its prolonged retention and high myocardium-to-blood ratios.

Prognostic implications of regional hyperkinesia and remote asynergy of noninfarcted myocardium.

To determine the clinical significance of regional hyperkinesia and remote asynergy of noninfarcted areas in patients with a first acute myocardial infarction (AMI), 2-dimensional echocardiography was performed in 113 consecutive patients within 12 hours after admission to the coronary care unit. In 98 patients (87%) all segments of the left ventricular wall were recorded. Infarct-associated asynergy was anterior in 63 and inferior in 35 patients. Regional hyperkinesia was present in 66 patients (67%)--44 of 63 with anterior (69%) and 22 of 35 with inferior (63%) infarcts--and was more frequently seen in patients with 1- and 2-vessel coronary artery disease (CAD) than in patients with 3-vessel CAD (87 and 72% vs 25%, p less than 0.001). In contrast to enzymatic infarct size, absence of regional hyperkinesia was significantly associated with a higher left ventricular wall motion score (p less than 0.01). Twenty patients died within 30 days after onset of AMI; in 15 (75%) regional hyperkinesia was absent. Absence of regional hyperkinesia, especially in anterior infarcts, was associated with a high mortality rate (13 of 19 patients [68%]). Remote asynergy, i.e., not adjacent to the infarct area and supposed to be related to another vascular region, was present in 17 of 98 patients (17%)--11 of 63 with anterior (17%) and 6 of 35 with inferior (17%) infarcts. Remote asynergy was present only in patients with multivessel CAD and was significantly related to a higher wall motion score (p less than 0.001), but not to enzymatic infarct size.(ABSTRACT TRUNCATED AT 250 WORDS)

Predictive value of two-dimensional echocardiographic and hemodynamic measurements on admission with acute myocardial infarction.

To identify high-risk patients with acute myocardial infarction, we compared admission values of two-dimensional echocardiography and hemodynamic monitoring. Left ventricular wall motion score (WMS), left ventricular stroke work index (LVSWI), and pulmonary capillary pressure (PCP) were obtained in 77 patients without clinical signs of heart failure. Progression into Killip grade 3 or 4 was found in 16 of 77 patients (21%) within 32 +/- 6 hours (mean +/- 1 standard deviation) after admission. Mean WMS, LVSWI, and PCP in those patients who developed severe pump failure were significantly different from those who did not: 13.4 +/- 4.9 versus 7.3 +/- 4, 30 +/- 4 versus 46 +/- 11 gm/m2, and 21 +/- 8 versus 12 +/- 6 mm Hg, respectively. Sensitivity of WMS of greater than 7 and LVSWI of less than 35 gm/m2 in predicting Killip grade 3 or 4 was 88% and 94%, specificity was 57% and 87%, positive predictive value was 35% and 65%, and negative predictive value was 95% and 98%. Sensitivity of PCP was low (50%). Early identification of patients developing myocardial rupture or reinfarction was limited by both methods. We conclude that echocardiographic examination on admission in patients with acute myocardial infarction provides an alternative approach for early identification of low-risk patients.

Myocardial uptake of iodinated free fatty acids and 201Tl in experimental ischemia.

In an experimental study, we evaluated the uptake of (131I)-17-iodo heptadecanoic acid (131I-HDA), (125I)-15-4 (4-iodophenyl) pentadecanoic acid (125I-PPA) and thallium-201 (201Tl) in the dog heart. Twenty dogs were studied and divided into 3 groups: in group A, 10 dogs (4 normal, 6 with coronary artery occlusion) were studied with 131I-HDA and 201Tl; in group B, 5 dogs (with occlusion) received 125I-PPA and 201Tl; and in group C, 5 dogs (with occlusion) were studied with 125I-PPA and 131I-HDA. Two min after administration of the compounds the hearts were excised and stored in formaldehyde. After sectioning of the left ventricle, total uptake was counted and expressed in percentage of injected dose. Uptake in the normal myocardium (group A) was 4.2 +/- 0.6% for 131I-HDA and 4.6 +/- 0.7% for 201Tl; in the occluded dog hearts (group A) we measured values of 2.6 +/- 0.4% for 131I-HDA (p less than 0.001) and 3.4 +/- 0.6% for 201Tl (p less than 0.01). Uptake of 131I-HDA, 125I-PPA and 201Tl in groups B and C was not significantly different: group B, 125I-PPA 2.8 +/- 0.8% and 201Tl 2.5 +/- 0.5%; group C, 125I-PPA 1.9 +/- 0.7% and 131I-HDA 1.6 +/- 0.6%. Moreover, regional distribution of both iodinated fatty acids was quite comparable with the distribution of 201Tl. We conclude that 131I-HDA and 125I-PPA show similar uptake as 201Tl and are distributed according to coronary artery perfusion, which underscores their value as myocardial imaging agents.

Determination of myocardial FFA elimination rates by functional images of uncorrected half-time values.

This paper presents an alternative method of demarcating regions of interest over the myocardium after administration of 123I-heptadecanoic acid to patients with coronary artery disease. In a matrix of 32 X 32 pixels the elimination rates of the radioactivity, which are not corrected for background activity, are visualized per pixel in a functional image. The functional image showed areas in the myocardium with high values of uncorrected elimination rates. These areas corresponded with the tracer defects on the scintigram. Corrected elimination rates obtained from regions of interest of functional images were comparable with those of scintigrams. Thus based on functional images of uncorrected elimination rates a reliable, objective determination of regions of interest over normal and abnormal myocardium can be made.

The prognostic value, clinical, and angiographic characteristics of patients with early postinfarction angina after a first myocardial infarction.

To evaluate the prognostic value of early postinfarction angina and its relationship to clinical and angiographic variables, 231 consecutive patients who had a first myocardial infarction were studied. All underwent cardiac catheterization within 10 weeks after admission to the hospital. There were no differences in basic characteristics or in ejection fraction, extent or severity of coronary artery disease, or collateral circulation between the patients with early postinfarction angina (n = 27) and those without early postinfarction angina (n = 204) except for the incidence of angina before myocardial infarction. Patients with early postinfarction angina had exercise-induced angina (42% vs 21%; p < 0.025) more frequently and shorter exercise duration (6.9 +/- 2.5 minutes vs 8.3 +/- 2.5 minutes; p = 0.007). Early postinfarction angina was associated with a significantly higher event rate (15% vs 4%; p < 0.025) and a significantly higher mortality rate (15% vs 3%; p < 0.005) in the first year after infarction but not during the subsequent 4-year follow-up. In patients with early postinfarction angina, stress test results had no predictive value for future cardiac events in contrast to patients without early postinfarction angina in whom ST-segment depression as observed on the stress test ECG and exercise duration had predictive value for future cardiac events. In patients with early postinfarction angina there was no relationship between the incidence of events and the number of diseased vessels in contrast to patients without early postinfarction angina who had a high incidence of events when three-vessel disease was present (16% vs 62%; p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Thallium-201 exercise testing in patients 6-8 weeks after myocardial infarction: limited value for the detection of multivessel disease.

In a clinical study, the value of exercise electrocardiography and thallium-201 scintigraphy was determined for the detection of multivessel disease in 176 patients 6-8 weeks after a first myocardial infarction. In all patients coronary arteriography was performed within 3 days after the non-invasive procedure. Of the 176 patients, 77 patients had multivessel disease (prevalence 44%). The exercise electrocardiogram was positive in 49 of these 77 patients (sensitivity 64%), while the thallium scintigram was positive in only 24 patients (sensitivity 31%). When the results of both procedures were added, a moderate sensitivity of 66% and a similar specificity of 62% was found; the positive and negative predictive values were 57% and 70%, respectively, and were considered too low for the adequate clinical diagnosis of multivessel disease after myocardial infarction. Based on our results, it is concluded that qualitative assessment of thallium exercise scintigraphy, alone or combined with electrocardiography, should not be used to predict the absence or presence of multivessel disease in patients after previous myocardial infarction.

Incorporation of radioiodinated fatty acids into cardiac phospholipids of normoxic canine myocardium.

The aim of this study was to assess the phospholipid distribution of radioiodinated 17-iodoheptadecanoic acid (IHDA), 15-(p-iodophenyl)pentadecanoic acid (p-IPPA) and 15-(p-iodophenyl)-3,3-dimethylpentadecanoic acid (DMIPPA) under normoxic conditions and to compare these data with the fatty acid composition of the phospholipid classes. After simultaneous i.v. injection of the radioiodinated fatty acids (I-123-IHDA; I-131-p-IPPA; I-125-DMIPPA) in open-chest dogs seven myocardial biopsies were taken over 40 min (n = 26). After lipid extraction of the biopsies the organic phase was analyzed for both neutral and polar lipids by two different TLC systems. The following polar lipid fractions were analyzed: lysophosphatidylcholine (LPC), sphingomyelin (SPH), phosphatidylcholine (PC; lecithin), phosphatidylinositol (PI), phosphatidylserine (PS), phosphatidylethanolamine (PE), diphosphatidylglycerol (DPG; cardiolipin) and neutral lipids. Fractions were counted in a gamma well counter and corrected for cross-over and recovery. Results of the polar phospholipids analysis showed that IHDA has the highest incorporation into the phospholipids. The IHDA was mainly incorporated into PI (45.6%) followed by PC (30.9%), PE (14.0%) and PS (5.6%). The p-IPPA was predominantly incorporated incorporated into PC (37.2%), followed by PS (20.1%) and PE (13.7%). In contrast to IHDA, incorporation of p-IPPA into PI was small (6.4%). The DMIPPA analogue was incorporated into phospholipids to only a very small degree, compared to IHDA and p-IPPA.(ABSTRACT TRUNCATED AT 250 WORDS)