Effects on coronary artery disease of lipid-lowering diet, or diet plus cholestyramine, in the St Thomas' Atherosclerosis Regression Study (STARS)

To assess the effect of dietary reduction of plasma cholesterol concentrations on coronary atherosclerosis, we set up a randomised, controlled, end-point-blinded trial based on quantitative image analysis of coronary angiograms in patients with angina or past myocardial infarction. Another intervention group received diet and cholestyramine, to determine the effect of a greater reduction in circulating cholesterol concentrations. 90 men with coronary heart disease (CHD), who had a mean (SD) plasma cholesterol of 7.23 (0.77) mmol/l were randomised to receive usual care (U, controls), dietary intervention (D), or diet plus cholestyramine (DC), with angiography at baseline and at 39 (SD 3.5) months. Mean plasma cholesterol during the trial period was 6.93 (U), 6.17 (D), and 5.56 (DC) mmol/l. The proportion of patients who showed overall progression of coronary narrowing was significantly reduced by both interventions (U 46%, D 15%, DC 12%), whereas the proportion who showed an increase in luminal diameter rose significantly (U 4%, D 38%, DC 33%). The mean absolute width of the coronary segments (MAWS) studied decreased by 0.201 mm in controls, increased by 0.003 mm in group D, and increased by 0.103 mm in group DC (p less than 0.05), with improvement also seen in the minimum width of segments, percentage diameter stenosis, and edge-irregularity index in intervention groups. The change in MAWS was independently and significantly correlated with LDL cholesterol concentration and LDL/HDL cholesterol ratio during the trial period. Both interventions significantly reduced the frequency of total cardiovascular events. Dietary change alone retarded overall progression and increased overall regression of coronary artery disease, and diet plus cholestyramine was additionally associated with a net increase in coronary lumen diameter. These findings support the use of a lipid-lowering diet, and if necessary of appropriate drug treatment, in men with CHD who have even mildly raised serum cholesterol concentrations.

Relation of angiographically defined coronary artery disease to plasma lipoprotein subfractions and apolipoproteins

The relation of coronary artery disease to plasma lipoproteins was examined in 104 men aged 35-65 years undergoing coronary angiography for suspected myocardial ischaemia. A score reflecting the number, degree, and length of stenoses in seven major coronary arteries was assigned to each angiogram. Lipid concentrations in lipoprotein subfractions were measured after preparative ultracentrifugation; plasma apolipoprotein concentrations were measured by electroimmunoassay. Men with high coronary scores tended to have lower plasma high-density lipoprotein (HDL) cholesterol concentrations and higher low-density lipoprotein (density 1.019-1.063 g/ml) cholesterol concentrations than subjects of similar age with low coronary scores (p approximately equal to 0.1). The strongest relation, however, was with the cholesterol concentration in the HDL2 subfraction (density 1.063-1.125 g/ml) of HDL, which averaged 44% lower in the severely affected patients (p less than 0.005). No associations were found between the coronary score and HDL3 cholesterol, the cholesterol content of lipoproteins of density less than 1.019 g/ml, plasma triglyceride, or the concentrations of apolipoproteins AI, AII, and E. The high coronary scores associated with low HDL2 concentrations reflected an increase in the number of both partial and complete stenoses distributed throughout the coronary tree. In contrast the sizes of the lesions and the proportion producing complete occlusion were unrelated to HDL2.

Family accommodation in obsessive-compulsive disorder

OBJECTIVE

Family accommodation of patients with obsessive-compulsive disorder, i.e., participation in symptoms and modification of personal and family routines, was assessed in relation to family stress, functioning, and attitudes toward the patient.

METHOD

Primary caretakers for 34 patients with obsessive-compulsive disorder were interviewed to assess the nature and frequency of accommodating behaviors. The caretakers also completed several measures of family functioning.

RESULTS

Of the 34 spouses or parents, 30 (88.2%) reported accommodating the patient. Family accommodation correlated with poor family functioning, rejecting attitudes toward the patient, and several types of family stress.

CONCLUSIONS

Family accommodation of patients with obsessive-compulsive disorder was associated with global family dysfunction and stress. This study suggests that families' efforts to accommodate patients may be intended to reduce patient anxiety or anger directed at relatives.

Interaction between transcription factors Sp1 and YY1

A basal level of transcription is usually observed when all but a small region of DNA has been deleted from a eukaryotic gene promoter. These promoter elements, which are necessary and sufficient for specific transcription initiation, are referred to as minimal or core promoter elements. One element that is commonly present in a core promoter is the initiator. It has been demonstrated that the presence of Sp1 binding sites can greatly enhance the level of transcription initiation at initiator elements. A binding site for the YY1 transcription factor, located at the initiation site of the adeno-associated virus P5 promoter, functions as an initiator element; a synergistic enhancement of its activity is observed in vitro when upstream Sp1 binding sites are present. Here we report that this synergistic activation probably occurs through protein-protein interactions.

Conversion of very low density lipoprotein to low density lipoprotein. A metabolic study of apolipoprotein B kinetics in human subjects

The interrelationship between apolipoprotein B in very low density lipoprotein (VLDL-B) and in low density lipoprotein (LDL-B) was studied in seven normal and hyperlipidemic men and women, with purified radioiodinated VLDL. The time-course of the appearance of radioactivity in LDL was followed. As the specific activity curves intersected at the masimal height of the LDL-B curve, it was inferred that all or most LDL-B peptide is derived from VLDL-B peptide. This transfer was further quantitated in seven normotriglyceridemic subjects by simultaneous i.v. injection of purified 131I-VLDL and 125I-LDL. By a deconvolution method, a quantitative description of the rate of entry of 131Ivldl-b into 131I-LDL-B was derived by analysis of 131I-LDL-B and 125I-ldl-b radioactivity in plasma. The results indicate that approximately 90% of VLDL-B mass is converted into LDL-B in subjects with normal serum triglyceride concentrations. The synthetic rates of VLDL-B and LDL-B peptide were simultaneously measured in six normal subjects, and two patients with heterozygous familial hypercholesterolemia (type IIa). The turnover rates for VLDL-B and LDL-B peptide were similar in these subjects. The findings in the three parts of this study were consistent with the view that most if not all VLDL-B is converted into LDL-B peptide, and most if not all LDL-B is derived from VLDL-B peptide in normotriglyceridemic subjects.

Selective retention of VLDL, IDL, and LDL in the arterial intima of genetically hyperlipidemic rabbits in vivo. Molecular size as a determinant of fractional loss from the intima-inner media

To explore possible mechanisms whereby the triglyceride-rich lipoproteins IDL and VLDL may promote atherosclerosis, fractional loss of these lipoproteins from the intima-inner media was measured in vivo in genetically hyperlipidemic rabbits of the St Thomas's Hospital strain and compared with the fractional loss of LDL, HDL, and albumin. These rabbits exhibit elevated plasma levels of VLDL, IDL, and LDL. In each rabbit, two aliquots of the same macromolecule, one iodinated with 125I and the other with 131I, respectively, were injected intravenously on average 24 and 3 hours, respectively, before removal of the aortic intima-inner media. The fractional loss from the intima-inner media of newly entered macromolecules was then calculated. The average fractional losses for VLDL, IDL, LDL, HDL, and albumin in lesioned aortic arches were 0.1%/h (n = 4), -0.2%/h (n = 3), 1.8%/h (n = 4), 11.4%/h (n = 3), and 26.3%/h (n = 1), respectively; in nonlesioned aortic arches fractional losses for IDL, LDL, HDL, and albumin were 1.7%/h (n = 1), 0.6%/h (n = 2), 14.6%/h (n = 3), and 25.9%/h (n = 3). In both lesioned and nonlesioned aortic arches, the logarithms of these fractional loss values were inversely and linearly dependent on the diameter of the macromolecules (R2 = .57, P = .001 and R2 = .84, P < .001), as determined from electron photomicrographs of negatively stained lipoproteins. These results suggest that after uptake into the arterial intima, VLDL and IDL as well as LDL are selectively retained in comparison with HDL and albumin.

Kinetic bases of the primary hyperlipidaemias: studies of apolipoprotein B turnover in genetically defined subjects

Autologous 131I-labelled very low density lipoprotein (VLDL) and 125I-labelled low density lipoprotein (LDL) were injected into seven normal subjects and into forty-three hyperlipidaemic patients, classified into groups on the basis of family studies and clinical findings, to quantitate VLDL and LDL apolipoprotein B kinetics. In normal subjects, mean VLDL-B peptide synthetic rate was 15 . 1 mg kg-1 day-1, mean LDL-B peptide synthetic rate 7 . 7 mg kg-1 day-1 and mean LDL-B fractional catabolic rate (FCR) 0 . 31 day-1. In heterozygous familial hypercholesterolaemia (n = 14) VLDL-B peptide production was normal in patients with normal triglyceride levels; in those with high triglyceride levels there was either VLDL overproduction or a catabolic defect. LDL-B peptide synthetic rates ranged from high normal to increased (8 . 5--18 . 0 mg kg-1 day-1) and LDL-B peptide FCR values were markedly reduced (0 . 14--0 . 28 day-1) confirming the presence of a defect in LDL catabolism but indicating over-production as well. In familial combined hyperlipidaemia (n = 11) VLDL-B peptide production ranged from normal to elevated (13 . 9--44 . 4 mg kg-1 day-1, mean 23 . 8 mg kg-1 day-1) correlating with the VLDl triglyceride level (i.e. with the phenotypic expression of the disorder). LDL-B peptide production ranged from high normal to markedly increased (8 . 9--19 . 5 mg kg-1 day-1, mean 12 . 2 mg kg-1 day-1) and correlated with LDL cholesterol levels (i.e. the phenotype), (r = +0 . 66, P < 0 . 05). Three patients with unclassified hypercholesterolaemia had increased LDL-B peptide synthetic rates. One patient with remnant hyperlipoproteinaemia (type III) had a high normal VLDL-B peptide synthetic rate, 17 . 3 mg kg-1 day-1, and a strikingly low FCR of VLDL-B. In familial hypertriglyceridaemia (three patients) there was a low VLDL-B peptide FCR. In unclassified hypertriglyceridaemia VLDL over-production was the finding in seven patients but four patients appeared to have catabolic defects only. Overall there were significant hyperbolic relationships between VLCL-B peptide FCR and VLDL-B peptide concentration (r = -0 . 78, P < 0 . 001, for the log/log relationship) and between LDL-B peptide FCR and LDL cholesterol (r = -0 . 88, P < 0 . 001 for the log/log relationship.)

Treatment of hyperlipidaemia retards progression of symptomatic femoral atherosclerosis. A randomised controlled trial

The effect of plasma lipid reduction on the progression of femoral atherosclerosis was studied in hyperlipidaemic patients with stable intermittent claudication. 24 patients were randomly assigned to treatment and usual-care groups, the former receiving dietary advice and cholestyramine, nicotinic acid, or clofibrate depending on their lipoprotein phenotype. Biplanar arteriography was performed when the study began and after a mean period of 19 months. Angiograms were assessed visually, with blinding, and by computerised image analysis. Therapy reduced mean plasma total cholesterol by 25%, mean low density lipoprotein (LDL) cholesterol by 28%, and mean plasma triglycerides by 45%. Significantly fewer arterial segments showed detectable progression of atherosclerosis in the treatment group. The mean increase in plaque area (mm2/segment/year) in the treatment group was only one third of that in the usual-care group. The mean increase in edge irregularity index (a measure of the severity of disease) in the treatment group was only 40% of that in the usual care group. Twice as many arterial segments showed improvement in the treatment group. In both groups changes in edge irregularity index were directly related to plasma LDL cholesterol concentration. This study, the first randomised controlled trial of its type, provides evidence that effective treatment of hyperlipidaemia favourably influences the natural history of symptomatic peripheral atherosclerosis.

Individual variation in the effects of dietary cholesterol on plasma lipoproteins and cellular cholesterol homeostasis in man. Studies of low density lipoprotein receptor activity and 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in blood mononuclear cells

The effects of dietary cholesterol on plasma lipoproteins and cholesterol homeostasis in blood mononuclear cells have been examined in healthy adults. Addition of 1,500 mg of cholesterol to the daily diet of 37 subjects for 14 d was associated with a wide range of response of plasma total cholesterol concentration (from -6 to +75 mg/dl; mean change, +29 mg/dl; P < 0.001). Increases in plasma cholesterol reflected increased cholesterol concentrations in intermediate density lipoprotein (IDL; 1.006-1.019 g/ml), low density lipoprotein (LDL; 1.019-1.063 g/ml), and the HDL(2) subclass (1.063-1.125 g/ml) of high density lipoprotein, which on average accounted for 20, 58, and 22%, respectively, of the total increment. Similar responses occurred in 14 other subjects given 750 mg cholesterol per day for 28 d. Plasma apolipoprotein B concentrations in IDL and LDL also increased. THESE EFFECTS ON PLASMA LIPOPROTEINS WERE ACCOMPANIED BY THREE CHANGES IN FRESHLY ISOLATED BLOOD MONONUCLEAR CELLS: (a) an increase in cell cholesterol content (mean change, +17%; P < 0.01); (b) suppression of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase activity (-32%; P < 0.001); and (c) reduction of LDL receptor activity (-74%; P < 0.01), quantified as the rate of degradation of (125)I-LDL to noniodide trichloroacetic acid-soluble material. These results provide the first direct evidence for the modulation of LDL receptor activity and HMG CoA reductase activity in a peripheral cell type in response to a dietary perturbation of human lipoprotein metabolism.The percentage increase in LDL cholesterol was negatively correlated with the percentage decrease in HMG CoA reductase activity (r = -0.49, P < 0.01). An additional negative correlation existed between the increment in plasma cholesterol concentration and the capacity of cells to degrade (125)I-LDL after derepression by preincubation for 72 h in lipoprotein-deficient medium (r = -0.74, P < 0.001). Thus, differences between individuals in the responses of the plasma lipoproteins to dietary cholesterol appear to be related in part to differences in the capacity of peripheral cells to catabolize LDL and to down-regulate cholesterol synthesis.

Reactive oxygen species generation by human spermatozoa is induced by exogenous NADPH and inhibited by the flavoprotein inhibitors diphenylene iodonium and quinacrine

Human spermatozoa possess a specialized capacity to generate reactive oxygen species (ROS) that is thought to be of significance in the redox regulation of sperm capacitation (De Lamirande and Gagnon, 1993; Aitken et al., 1995). However, the mechanisms by which ROS are generated by these cells are not understood. In this study we have examined the possible significance of NADPH as a substrate for ROS production by human spermatozoa. Addition of NADPH to viable populations of motile spermatozoa induced a sudden dose-dependent increase in the rate of superoxide generation via mechanisms that could not be disrupted by inhibitors of the mitochondrial electron transport chain (antimycin A, rotenone, carbonyl cyanide m-chlorophenylhydrazone [CCCP], and sodium azide), diaphorase (dicoumarol) xanthine oxidase (allopurinol), or lactic acid dehydrogenase (sodium oxamate). However, NADPH-induced ROS generation could be stimulated by permeabilization and was negatively correlated with sperm function. Both NADH and NADPH were active electron donors in this system, while NAD+ and NADP+ exhibited little activity. Stereo-specificity was evident in the response in that only the beta-isomer of NADPH supported superoxide production. The involvement of a flavoprotein in the electron transfer process was indicated by the high sensitivity of the oxidase to inhibition by diphenylene iodonium and quinacrine. These results indicate that NAD(P)H can serve as an electron donor for superoxide generation by human spermatozoa and present a simple strategy for the production of motile populations of free radical generating cells with which to study the significance of these molecules in the control of normal and pathological sperm function.

Muscle strength as a predictor of bone mineral density in young women

It is widely accepted that physical activity is beneficial to bone. However, the specific relationships of muscle strength to bone mineral density (BMD) are poorly understood. We examined strength and BMD in 59 women aged 18-31 years who ranged in exercise patterns from sedentary to active. Mineral density of the right proximal femur (hip) and spine (L2-4) was evaluated by dual-energy x-ray absorptiometry. BMD at the midradius was measured by single-photon absorptiometry. Dynamic strength (one repetition maximum) was measured for the following muscle groups: back, elbow flexors (biceps), leg extensors (quadriceps), and the hip flexors, extensors, adductors, and abductors. Isometric grip strength was assessed by dynamometry. Mineral density at the hip correlated independently with muscle strength and body weight, but not with age. Specifically, femoral neck BMD was significantly correlated with back strength and weight, whereas trochanter and overall hip mineral density were significantly related to biceps, back, and hip adductor strength. Hip mineral density was not related to strength of the quadriceps groups or to that of the hip flexors, extensors, or abductors. In addition, muscle strength was an independent predictor of lumbar spine and midradius mineral density. In stepwise multiple regression analysis, biceps strength proved the most robust predictor of hip BMD and grip strength best predicted bone density at the lumbar spine and radius. We conclude that muscle strength is an independent predictor of bone mineral density, accounting for 15-20% of the total variance in bone density of young women.(ABSTRACT TRUNCATED AT 250 WORDS)

Commentary on Ferguson, et al., "Impact of Non-pharmaceutical Interventions (NPIs) to Reduce COVID-19 Mortality and Healthcare Demand"

A recent manuscript (Ferguson et al. in Impact of non-pharmaceutical interventions (NPIs) to reduce COVID-19 mortality and healthcare demand, Imperial College COVID-19 Response Team, London, 2020. https://www.imperial.ac.uk/media/imperial-college/medicine/sph/ide/gida-fellowships/Imperial-College-COVID19-NPI-modelling-16-03-2020.pdf) from Imperial College modelers examining ways to mitigate and control the spread of COVID-19 has attracted much attention. In this paper, we will discuss a coarse taxonomy of models and explore the context and significance of the Imperial College and other models in contributing to the analysis of COVID-19.

Absorption of vitamin D3-3H in control subjects and patients with intestinal malabsorption

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Plasma triglyceride and high density lipoprotein cholesterol as predictors of ischaemic heart disease in British men. The Caerphilly and Speedwell Collaborative Heart Disease Studies

OBJECTIVE

To assess the roles of plasma triglyceride and high density lipoprotein (HDL) cholesterol concentrations in predicting ischaemic heart disease.

DESIGN

Two prospective cohort studies with common core protocols.

SETTING AND PARTICIPANTS

Both cohorts are 100% samples of middle aged men. In Caerphilly the 2512 men were living within a defined area. In Speedwell the 2348 men were registered with local general practitioners.

MAIN OUTCOME MEASURES

Fasting blood samples were taken at initial examination and plasma lipid concentrations were measured. Major ischaemic heart disease events were assessed from hospital notes, death certificates, and electrocardiograms.

RESULTS

At first follow up, after an average of 5.1 years in Caerphilly and 3.2 years in Speedwell, 251 major ischaemic heart disease events had occurred. Men with triglyceride concentrations in the top 20% of the distribution had a relative odds value for ischaemic heart disease of 2.3 (95% confidence interval (95% CI) 1.3 to 4.1) compared with men in the bottom 20%, after adjusting for both plasma total and HDL cholesterol, and non-lipid risk factors. Men in the lowest 20% of the distribution of HDL cholesterol concentration had a relative odds value of 1.7 (95% CI 1.0 to 2.8) compared with the top 20%, after adjustment was made for total cholesterol and triglyceride concentrations, and non-lipid risk factors. These relations were not caused by beta blockers, which were being taken by 5% of the men.

CONCLUSIONS

Plasma triglyceride concentration predicts major ischaemic events after allowance is made for total and HDL cholesterol concentrations and other risk factors. In these populations, triglyceride is a more important predictor than total cholesterol concentration.

Serum bile acids in liver disease

Serum bile acids have been measured in patients with a wide variety of liver diseases using a technique which separates the major individual conjugated and free bile acids. Total serum bile acids may be elevated up to 100 times the normal concentration in patients with liver disease and this increase consists largely of conjugated bile acids. The ratio of glycine-conjugated to taurine-conjugated bile salts is low in all types of liver disease and this is found particularly in the serum of patients with obstructive jaundice. There is a decrease in the ratio of trihydroxy:dihydroxy cholanic acid in patients with cirrhosis.

Small bowel mucosal injury is reduced in healthy subjects treated with celecoxib compared with ibuprofen plus omeprazole, as assessed by video capsule endoscopy

BACKGROUND

Small bowel mucosal injury associated with non-selective non-steroidal anti-inflammatory drugs is being increasingly recognized.

AIM

To evaluate the incidence of small bowel injury in healthy subjects receiving celecoxib or ibuprofen plus omeprazole using video capsule endoscopy (VCE).

METHODS

Subjects with normal baseline VCE were randomly assigned to receive celecoxib 200 mg b.d., ibuprofen 800 mg t.d.s. plus omeprazole 20 mg o.d. or placebo for 2 weeks. The primary end point was mean number of small bowel mucosal breaks per subject. Secondary end points included correlation of faecal calprotectin levels with the primary outcome.

RESULTS

After treatment, the mean number of small bowel mucosal breaks per subject and the percentage of subjects with mucosal breaks were 0.7/25.9% for ibuprofen/omeprazole compared with 0.2/6.4% for celecoxib and 0.1/7.1% placebo (both comparisons P < 0.001). There were no significant differences between celecoxib and placebo in any measure. Mean increases in faecal calprotectin levels were higher in subjects receiving ibuprofen/omeprazole compared with celecoxib (P < 0.001), but no correlation was determined between these levels and small bowel mucosal breaks.

CONCLUSIONS

Among healthy subjects with no baseline endoscopic lesions, celecoxib was associated with significantly fewer small bowel mucosal breaks than ibuprofen/omeprazole as assessed by VCE.

Blood lipid concentrations and other cardiovascular risk factors: distribution, prevalence, and detection in Britain

To establish the distribution of blood lipid concentrations and the prevalences of other risk factors for cardiovascular disease in Britain 12,092 men and women aged 25-59 in Glasgow, Leicester, London, and Oxford were studied. Subjects were selected by opportunistic case finding, in which patients consulting their general practitioner for any reason were offered a health check by appointment, or random selection from age-sex registers, in which an invitation for a health check was posted. The overall rate of response was 73%, being 91-94% by opportunistic case finding and 36-63% by random selection. At the health check subjects answered a brief questionnaire about risk factors for cardiovascular disease, and their height, weight, and blood pressure were recorded; a blood sample was taken for measuring plasma concentrations of cholesterol, triglyceride, high density lipoprotein cholesterol, and glucose. The mean cholesterol concentrations were 5.9 (SD 1.2) and 5.8 (1.2) mmol/l in men and women, respectively. In London the mean value was 5.5 (1.2) mmol/l for both men and women and was significantly lower than mean values in the three other centres, among which there were no significant differences. In men and women aged 25-29 concentrations were similar but they increased in men until the age of 45-49, after which they showed no further increase; in women concentrations did not increase until the age of 40-44 and by the age of 50-59 values were higher than in men. Mean triglyceride concentrations were significantly higher in men than in women (1.8 (1.4) v 1.3 (0.9) mmol/l, respectively), and trends with age were similar to those for cholesterol concentrations, except that at no age were values higher in women than in men. Mean triglyceride values overall were higher in Glasgow and London than in Oxford and Leicester. Body mass index was higher in Glasgow and London than in the other two centres and correlated with systolic and diastolic blood pressures and triglyceride concentration. In addition, subjects in Glasgow smoked significantly more than those in the other centres. These observations could contribute to the higher rate of coronary heart disease in Glasgow. Plasma lipid concentrations and the prevalences of other risk factors for cardiovascular disease were similar in subjects selected by opportunistic case finding and by random selection. In Britain cholesterol values have changed little during the past 12 years despite dietary recommendations and health education.(ABSTRACT TRUNCATED AT 400 WORDS)

Structural relationships among Rhizobium meliloti symbiotic promoters

Symbiotic nitrogen fixation by Rhizobium meliloti requires the developmentally specific expression of certain bacterial genes. One set of these genes encodes the subunits of nitrogenase, the enzyme responsible for the reduction of atmospheric dinitrogen to ammonia, and another set consists of closely linked genes also essential for nitrogen fixation. Examination of promoter and probable regulatory regions for these gene sets has revealed extensive DNA sequence conservation for more than 160 bp upstream of the respective transcription start points. Three such promoter regions have been identified in the nitrogen fixation (nif) gene cluster of R. meliloti strain 102F34. Using one of these promoter regions as a hybridization probe, three additional sequences were found in the genome of this strain. The DNA of other R. meliloti strains and Rhizobium species were also examined for homology to the symbiotically regulated promoters of R. meliloti 102F34. DNA sequences homologous to these R. meliloti promoters were found among diverse rhizobia, and in at least some cases were associated with nif genes.

Coronary artery reperfusion in acute myocardial infarction: beneficial effects of intracoronary streptokinase on left ventricular salvage and performance

Coronary angiography was performed on hospital admission in 37 patients with acute myocardial infarction (AMI). Thirty patients had total occlusion of the infarct-related coronary artery and seven patients had severe proximal stenoses with poor distal flow. In 20 of 30 patients with total occlusion, intracoronary (IC) infusion of streptokinase (SK) resulted in reperfusion of the distal coronary artery. Left ventricular (LV) performance was assessed before coronary angiography and at discharge from the hospital by use of gated cardiac blood pool imaging techniques. In patients evidencing reperfusion of the infarct-related coronary artery, mean (+/- SD) left ventricular ejection fraction (LVEF) increased from admission through discharge (46% +/- 15% to 55% +/- 10%, p = 0.002). In contrast, LVEF did not change from admission through discharge in patients with severe proximal stenoses alone or in patients with total occlusion who did not demonstrate reperfusion following SK administration (47% +/- 17% vs 49% +/- 18%, p = ns). In an additional 14 control patients with AMI who were not evaluated with coronary angiography, LVEF did not change from admission through discharge (46% +/- 12% vs 48% +/- 14%, p = ns). Quantitative thallium-201 perfusion imaging demonstrated an increase (p less than 0.05) in thallium uptake in the infarct segment following coronary artery reperfusion. In contrast, thallium uptake did not change (p = ns) in the infarct segment in patients not evidencing angiographic coronary artery reperfusion. These data support the following : (1) Coronary artery thrombus occurs frequently in AMI and can be lysed by IC SK, and (2) reperfusion with IC SK in patients with evolving myocardial infarction results in myocardial salvage and improved LV performance through hospital discharge.