Metoprolol CR/XL in patients with heart failure: A pilot study examining the tolerability, safety, and effect on left ventricular ejection fraction

BACKGROUND

This study was designed to investigate the tolerability, safety, and effect on left ventricular function of a new long-acting preparation of metoprolol, metoprolol succinate (CR/XL).

METHODS AND RESULTS

Sixty patients were randomly assigned with a 2:1 ratio, drug versus placebo, administered with a gradually increasing dose of 12.5 to 150 mg of blinded medication during an 8-week period and continued for 6 months. The average peak dose achieved was 99 mg and 132 mg in the metoprolol succinate and placebo groups, respectively. The drug was well tolerated and there was no significant difference in drug withdrawals, New York Heart Association class, or quality of life assessment. The increase in left ventricular ejection fraction measure at baseline and 6 months measured by radioisotopic ventriculography was greater in the metoprolol succinate group (27. 5% to 36.3%) than in the placebo group (26% to 27.9%) (P <.015). Examination of serial Holter electrocardiographic recordings indicate that metoprolol succinate therapy was associated with a significant (P <.05) decrease in total ventricular ectopy at 8 weeks of therapy and a decrease in ventricular couplets and nonsustained ventricular tachycardia at 8 through 26 weeks of therapy. No changes were observed in plasma norepinephrine during therapy except a transitory significant (P <.05) increase in N terminal proatrial natriuretic factor at 8 weeks in the metoprolol succinate group.

CONCLUSIONS

This study indicates that treatment with metoprolol succinate for a 6-month period is safe and well tolerated and is associated with an increase in left ventricular ejection fraction and a decrease in ventricular ectopic beats.

Lack of association of a common polymorphism of the plasminogen activator inhibitor-1 gene with coronary artery disease and myocardial infarction

OBJECTIVES

The study was done to assess whether the common polymorphic allele (4G) of the plasminogen activator inhibitor-1 (PAI-1) gene is associated with coronary artery disease (CAD) or myocardial infarction (MI).

BACKGROUND

Impaired fibrinolytic function has been associated with CAD and MI. Plasminogen activator inhibitor-1 plays a central role in intravascular thrombosis and thrombolysis; the common insertion/deletion polymorphism (4G/5G) of PAI-1 has been correlated with altered PAI-1 levels and proposed as a coronary risk factor.

METHODS

Blood was drawn and DNA extracted from 1,353 consenting patients undergoing coronary angiography. The 4G and 5G alleles of PAI-1 were amplified using specific primers. Amplified products were visualized by staining with ethidium bromide after electrophoresis in 1.5% agarose.

RESULTS

Patient age averaged 63.5 (SD 11.7) years; 70% were men, 28% had a history of MI, 66% had severe CAD (>60% stenosis), and 23% had no CAD or MI. Overall, the frequency of the 4G allele was 54.2%, and 78% of patients were 4G carriers. Genotypic distributions were: 4G/4G = 30.1%, 4G/5G = 47.9%, and 5G/5G = 21.8%. Neither carriage of 4G (CAD odds ratio [OR] = 1.08 [0.80 to 1.46], MI OR = 1.11 [0.83 to 1.49]) nor 4G/4G homozygosity (CAD OR = 1.07, MI OR = 0.98) was associated with CAD or MI. In multivariate analyses, risk factors associated with CAD were (in order): gender, age, smoking, diabetes, cholesterol, and hypertension; for MI, they were gender, smoking, and cholesterol.

CONCLUSIONS

A common PAI-1 polymorphism (4G) was not importantly associated with angiographic CAD or history of MI in a Caucasian population. Modest risk (i.e., OR <1.5), especially for MI, or risk in association with other factors, cannot be excluded.

Beta-blocker use and survival in patients with ventricular fibrillation or symptomatic ventricular tachycardia: the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial

OBJECTIVES

To evaluate whether use of beta-adrenergic blocking agents, alone or in combination with specific antiarrhythmic therapy, is associated with improved survival in persons with ventricular fibrillation (VF) or symptomatic ventricular tachycardia (VT).

BACKGROUND

The ability of beta-blockers to alter the mortality of patients with VF or VT receiving contemporary medical management is not well defined.

METHODS

Survival of 1,016 randomized and 2,101 eligible, nonrandomized patients with VF or symptomatic VT followed in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial through December 31, 1996 was assessed using Cox proportional hazards analysis.

RESULTS

The 817 (28%) patients discharged from hospital receiving beta-blockers had less ventricular dysfunction, fewer symptoms of heart failure and a different pattern of medication use compared with patients not receiving beta-blockers. Before adjustment for important prognostic variables, beta-blockade was not significantly associated with survival in randomized or in eligible, nonrandomized patients treated with specific antiarrhythmic therapy. After adjustment, beta-blockade remained unrelated to survival in randomized or in eligible, nonrandomized patients treated with amiodarone alone (n = 1142; adjusted relative risk [RR] = 0.96; 95% confidence interval [CI] 0.64-1.45; p = 0.85) or a defibrillator alone (n = 1347; adjusted RR = 0.88; 95% CI 0.55 to 1.40; p = 0.58). In contrast, beta-blockade was independently associated with improved survival in eligible, nonrandomized patients who were not treated with specific antiarrhythmic therapy (n = 412; adjusted RR = 0.47; 95% CI 0.25 to 0.88; p = 0.018).

CONCLUSIONS

Beta-blocker use was independently associated with improved survival in patients with VF or symptomatic VT who were not treated with specific antiarrhythmic therapy, but a protective effect was not prominent in patients already receiving amiodarone or a defibrillator.

Cytomegalovirus induction of interleukin-6 in lung fibroblasts occurs independently of active infection and involves a G protein and the transcription factor, NF-kappaB

Cytomegalovirus (CMV) infection induces the proinflammatory cytokine, interleukin (IL)-6, which may contribute to the pathology of the infection. In vitro CMV induction of IL-6 by human lung fibroblasts was studied. The quantity of cytokine in culture supernatants was maximal 20 h after infection and decreased thereafter. Transcription of the IL-6 gene and IL-6 protein expression were equally stimulated by infectious and UV-inactivated virus (CMV-UV). CMV-UV-stimulated IL-6 was inhibited by pyrrolidinedithiocarbamate (an inhibitor of the transcription factor, NF-kappaB) and by pertussis toxin (suggesting the involvement of a G protein) and occurred in the absence of CMV immediate-early antigen transcription. Neutralizing antibodies to IL-1beta or tumor necrosis factor-alpha did not affect CMV-UV-induced IL-6, but expression was inhibited by antibody to the CMV attachment glycoprotein. IL-6 production by fibroblasts occurs independently from productive infection but has characteristics that suggest a ligand receptor-mediated pathway. This function may be important in pathology or disease resolution.

Determination of corpora lutea numbers in Booroola--Texel ewes using transrectal ultrasound

Ovulation rates in Booroola--Texel ewes are currently determined by laparoscopic examination of the ovaries during the luteal phase allowing for carrier status of the ewe to be diagnosed. However, this is an invasive procedure and the aim of this work was to determine whether or not transrectal ultrasound would be an acceptable and accurate alternative to laparoscopy for this purpose in ewes. Transrectal ultrasound was performed using a 5.0 MHz transducer in 18 ewes restrained in the standing position. They were then euthanized and laparoscopy was performed, following which the reproductive tracts were recovered. An additional 22 ewes were subjected to scanning in dorsal recumbency, using a 7.5 MHz transducer, at various stages of the luteal phase before being euthanized and the reproductive tracts recovered. The ovarian structures identified using each method were then compared. The results demonstrated that laparoscopy is an accurate method of determining ovulation rates in ewes. Transrectal ultrasound examination appeared to be an acceptable and non-invasive procedure. The use of a 7.5 MHz transducer with the ewes in dorsal recumbency produced the best results and clearest images of the ovaries, which allowed for the determination of the number of corpora lutea (CL) and the presence of other structures. Accuracy improved with experience in the technique, the stage of the luteal phase at which the examination was performed, the number of CL present in the ovary and the age of the ewe. Further work is needed to confirm this finding due to the small numbers of animals in the present study. This ultrasound technique, however, has the potential to provide an alternative to laparoscopy for the determination of numbers of CL in ewes.

Design and results of the antiarrhythmics vs implantable defibrillators (AVID) registry. The AVID Investigators

BACKGROUND

The Antiarrhythmics Versus Implantable Defibrillators (AVID) Study compared treatment with implantable cardioverter-defibrillators versus antiarrhythmic drugs in patients with life-threatening ventricular arrhythmias (VAs). AVID maintained a Registry on all patients, randomized or not, with any VA or unexplained syncope who could be considered for either of the treatment strategies. Trial-eligible arrhythmias were the categories of VF cardiac arrest, Syncopal VT, and Symptomatic VT, below.

METHODS AND RESULTS

Of 5989 patients screened, 4595 were registered and 1016 were randomized. Mortality follow-up through 1996 was obtained on the 4219 Registry patients enrolled before 1997 through the National Death Index. Crude mortality rates (mean+/-SD, follow-up, 16.9+/-11.5 months) were: VF cardiac arrest, 17.0% (n=1399, 238 deaths); Syncopal VT, 21.2% (n=598, 127 deaths); Symptomatic VT, 15.8% (n=1065, 168 deaths); Stable (asymptomatic) VT, 19.7% (n=497, 98 deaths); VT/VF with transient/correctable cause, 17.8% (n=270, 48 deaths); and Unexplained syncope, 12.3% (n=390, 48 deaths).

CONCLUSIONS

Patients with seemingly lower-risk or unknown-risk VAs (asymptomatic VT, and VT/VF associated with a transient factor) have a (high) mortality similar to that of higher-risk, AVID-eligible VAs. The similar (and poor) prognosis of most patients with VT/VF suggests the need for reevaluation of a priori risk grouping and raises the question of the appropriate arrhythmia therapy for a broad range of patients.

Randomized secondary prevention trial of azithromycin in patients with coronary artery disease and serological evidence for Chlamydia pneumoniae infection: The Azithromycin in Coronary Artery Disease: Elimination of Myocardial Infection with Chlamydia (ACADEMIC) study

BACKGROUND

Chlamydia pneumoniae commonly causes respiratory infection, is vasotropic, causes atherosclerosis in animal models, and has been found in human atheromas. Whether it plays a causal role in clinical coronary artery disease (CAD) and is amenable to antibiotic therapy is uncertain.

METHODS AND RESULTS

CAD patients (n=302) who had a seropositive reaction to C pneumoniae (IgG titers >/=1:16) were randomized to receive placebo or azithromycin, 500 mg/d for 3 days, then 500 mg/wk for 3 months. Circulating markers of inflammation (C-reactive protein [CRP], interleukin [IL]-1, IL-6, and tumor necrosis factor [TNF]-alpha), C pneumoniae antibody titers, and cardiovascular events were assessed at 3 and 6 months. Treatment groups were balanced, with age averaging 64 (SD=10) years; 89% of the patients were male. Azithromycin reduced a global rank sum score of the 4 inflammatory markers at 6 (but not 3) months (P=0. 011) as well as the mean global rank sum change score: 531 (SD=201) for active drug and 587 (SD=190) for placebo (P=0.027). Specifically, change-score ranks were significantly lower for CRP (P=0.011) and IL-6 (P=0.043). Antibody titers were unchanged, and number of clinical cardiovascular events at 6 months did not differ by therapy (9 for active drug, 7 for placebo). Azithromycin decreased infections requiring antibiotics (1 versus 12 at 3 months, P=0.002) but caused more mild, primarily gastrointestinal, adverse effects (36 versus 17, P=0.003).

CONCLUSIONS

In CAD patients positive for C pneumoniae antibodies, global tests of 4 markers of inflammation improved at 6 months with azithromycin. However, unlike another smaller study, no differences in antibody titers and clinical events were observed. Longer-term and larger studies of antichlamydial therapy are indicated.

Association of lipoprotein lipase gene polymorphisms with coronary artery disease

OBJECTIVES

The purpose of this study was to test whether the HindIII (+) and PvuII (-) or (+) restriction enzyme-defined alleles are associated with angiographic coronary artery disease (CAD).

BACKGROUND

Lipoprotein lipase (LPL) plays a central role in lipid metabolism, hydrolyzing triglyceride in chylomicrons and very low density lipoproteins. Polymorphic variants of the LPL gene are common and might affect risk of CAD.

METHODS

Blood was drawn from 725 patients undergoing coronary angiography. Leukocyte deoxyribonucleic acid segments containing the genomic sites were amplified by the polymerase chain reaction and digested, and polymorphisms were identified after electrophoresis in 1.5% agarose gel.

RESULTS

In no-CAD control subjects (n = 168), HindIII (-) and (+) allelic frequencies were 28.6% and 71.4%, and (-) and (+) alleles were carried by 44.0% and 86.9% of subjects, respectively. Control PvuII (-) and (+) allelic frequencies were 41.7% and 58.3%, and (-) and (+) alleles were carried by 64.3% and 81.0%, respectively. In CAD patients (>60% stenosis; n = 483), HindIII (+) allelic carriage was increased (93.8% of patients, odds ratio [OR] = 2.28, confidence interval [CI] 1.27 to 4.00). Also, PvuII (-) allelic carriage tended to be more frequent in CAD patients (OR = 1.33, CI 0.92 to 1.93). Adjusted for six CAD risk factors and the other polymorphism, HindIII (+) carriage was associated with an OR = 2.86, CI 1.50 to 5.42, p = 0.0014, and PvulI (-) carriage, OR = 1.42, CI 0.95 to 2.12, p = 0.09. The two polymorphisms were in strong linkage disequilibrium, and a haplotype association was suggested.

CONCLUSIONS

The common LPL polymorphic allele, HindIII (+), is moderately associated with CAD, and the PvuII (-) allele is modestly associated (trend). Genetic variants of LPL deserve further evaluation as risk factors for CAD.

Sotalol: An important new antiarrhythmic

Sotalol, the most recently approved oral antiarrhythmic drug, has a unique pharmacologic profile. Its electrophysiology is explained by nonselective beta-blocking action as well as class III antiarrhythmic activity (including fast-activating cardiac membrane-delayed rectifier current blockade), which leads to increases in action potential duration and refractory period throughout the heart and in QT interval on the surface electrocardiogram. Its better hemodynamic tolerance than other beta-blockers may be a result of enhanced inotropy associated with class III activity. Sotalol's ability to suppress ventricular ectopy is similar to that of class I agents and better than that of standard beta-blockers. Unlike class I agents, its use in a postinfarction trial was not associated with increased mortality rate. Therapeutically, it has shown superior efficacy for prevention of recurrent ventricular tachycardia and ventricular fibrillation, which was the basis for its approval. In a randomized study, the Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) trial, sotalol was associated with an increased in-hospital efficacy prediction rate (by Holter monitor or electrophysiologic study), reduced long-term arrhythmic recurrence rate with superior tolerance, and lower mortality rate than class I ("standard") antiarrhythmic drugs. Sotalol was 1 of 2 drugs selected for comparison with implantable defibrillators in the recent National Institutes of Health Antiarrhythmics versus Implantable Defibrillator (AVID) study. Sotalol appears to be a preferred drug for use with implantable defibrillators; unlike some other agents (eg, amiodarone) it does not elevate and, indeed, may lower defibrillation threshold. Although unapproved for this use, sotalol is active against atrial arrhythmias. It has shown efficacy equivalent to propafenone and quinidine in preventing atrial fibrillation recurrence, but it is better tolerated than quinidine and provides excellent rate control during recurrence. Sotalol's major side effects are related to beta-blockade and the risk of torsades de pointes (acceptably small if appropriate precautions are taken). Unlike several other antiarrhythmics (eg, amiodarone), it has no pharmacokinetic drug-drug interactions, is not metabolized, and is entirely renally excreted. Initial dose is 80 mg twice daily, with gradual titration to 240 to 360 mg/day as needed. The daily dose must be reduced in renal failure. On the basis of favorable clinical trials and practice experience, sotalol has shown a steadily growing impact on the treatment of arrhythmias during its 5 years of market availability, a trend that is likely to continue.

Associations between a polymorphism in the gene encoding glycoprotein IIIa and myocardial infarction or coronary artery disease

OBJECTIVES

The purpose of this study was to determine whether a common variant (PIA2) of the membrane glycoprotein (GP) IIIa gene is associated with myocardial infarction (MI) or coronary artery disease (CAD).

BACKGROUND

Platelet GP IIb/IIIa is believed to play a central role in MI, binding fibrinogen, cross-linking platelets and initiating thrombus formation. Genetically determined differences in binding properties of GP IIb/IIIa might result in changes in platelet activation or aggregation and affect the risk of MI or CAD.

METHODS

To determine associations (odds ratios [OR] > or =1.5 to 2.0) of genotype with MI or CAD, blood was drawn from 791 patients (pt) undergoing angiography. A 266 base pair fragment of the GP IIIa gene was amplified by the polymerase chain reaction and digested with the MspI restriction enzyme. Genotypes were identified after electrophoresis of digestion products in 1.5% agarose gel.

RESULTS

Of the 791 pt, 225 had acute (n = 143) or previous MI, and 276 did not have MI or unstable angina. The PI(A2) allele was carried by 33.8% of MI pt versus 26.9% of no-MI control subjects, OR = 1.39 (95% CI, 0.95 to 2.04, p = 0.09). Angiographically, 549 pt had severe (>60% coronary stenosis) CAD, and 170 had normal coronary arteries (<10% stenosis). The PI(A2) allele was found in 31.0% of CAD pt versus 28.2% of no-CAD control subjects, OR = 1.14 (CI, 0.78 to 1.67, p = 0.50). When adjusted for six standard risk factors, ORs were 1.47 (CI, 0.98 to 2.20, p = 0.062) for MI and 1.20 (CI, 0.80 to 1.81, p = 0.38) for CAD.

CONCLUSIONS

The PI(A2) variant of the gene encoding GP IIIa is modestly associated (OR approximately 1.5) with nonfatal MI but shows little if any association with CAD per se.

Yearly rates of rod and cone functional loss in retinitis pigmentosa and cone-rod dystrophy

OBJECTIVE

To provide the first measures of the relative rates of rod and cone functional loss in patients with retinitis pigmentosa (RP) or cone-rod dystrophy (CRD).

DESIGN

Five-year, prospective natural history study.

PARTICIPANTS

Ninety-six patients (67 with RP and 29 with CRD) retaining measurable rod-mediated visual function and 5 normal subjects were tested at baseline and annually for 4 consecutive years.

MAIN OUTCOME MEASURES

Tests of visual function included visual acuity, dark-adaptation thresholds, dark-adapted static perimetry, and rod and cone computer-averaged electroretinograms (ERGs), which were obtained over a range of retinal illuminances. Intervisit variability for each measure was obtained in a subset of patients who were tested twice within a 2-month interval and was used to determine whether an individual patient had shown progression, regression, or no change over a particular study interval.

RESULTS

Over a 4-year interval, a significant number of patients with RP (60%) and CRD (62%) showed a decline in cone ERG amplitude. For rod ERG amplitude, the percentage of patients with RP or CRD showing progression was 64% and 45%, respectively. Although visual acuity, dark-adapted threshold, and rod visual field area also declined significantly over the 4-year period, the mean rate of change and the numbers of patients showing progression on these measures were lower than those for ERG measures. On specialized ERG testing, the yearly change in rod ERG threshold in RP was greater than the yearly change in cone ERG threshold, and the rate of progression varied significantly among inheritance types. For patients with CRD, the yearly change in rod threshold was comparable to the yearly change in cone ERG threshold.

CONCLUSIONS

This study helps to define the natural progression of rod-mediated and cone-mediated functional loss in patients with RP and CRD.

Confirmation of linkage of hereditary partial lipodystrophy to chromosome 1q21-22

Familial lipodystrophy is a genetically heterogeneous set of disorders characterized by a total or partial absence of subcutaneous fat, diabetes mellitus or impaired glucose tolerance, hyperlipidemia, and hypermetabolism [Senior and Gellis, 1964]. One subtype, familial partial lipodystrophy Dunnigan (FPLD), is a rare autosomal dominant trait that results in an gradual loss of subcutaneous fat in the lower trunk and limbs, Type V hyperlipoproteinemia, hypertriglyceridemia, and insulin-resistant diabetes. Previous reports of this condition have been limited to case reports or very small families. Recently, Peters et al. reported on linkage of five families of Western European descent to a 5.3 cM region on chromosome 1q21-22 between the flanking markers D1S305 and D1S1600 [Peters et al., 1998: Nat Genet 18:292-295]. We performed linkage and haplotype analysis using highly polymorphic, microsatellite markers on a large, multigeneration Caucasian kindred of German ancestry. The maximum two-point lod score achieved was 4.96 at theta(max) = 0 for marker D1S2721. Multipoint analysis gave an overall maximum lod score of 6.27 near marker D1S2721. The results of the haplotype analysis support the minimal candidate region as reported by Peters et al.

Genetic mapping of a novel familial form of infantile hemangioma

Infantile hemangiomas are the most common tumor of infancy, occurring with an incidence of up to 10% of all births. They are benign but highly proliferative lesions involving aberrant localized growth of capillary endothelium. Although most hemangiomas occur sporadically and as single lesions, or in conjunction with pleiotropic genetic syndromes, we have previously identified six kindreds where hemangiomas appear to segregate as an autosomal dominant trait with high penetrance. Four such families contain affected individuals in three or more generations. In the current study, blood samples from five of these families were collected and used in a whole genome linkage search at 10-cM resolution. We established evidence for linkage to 5q in three families, and evidence for locus heterogeneity. The three 5q-linked families were further genotyped to generate haplotype information and narrow the candidate interval. Based on recombination breakpoint analysis, the interval exists between markers D5S2490 and D5S408, spanning 55 cM, and corresponding to 5q31-33. Using information from affected and unaffected individuals, the interval spans 38 cM between markers D5S1469 and D5S211. Three candidate genes involved with blood vessel growth map to this region: fibroblast growth factor receptor-4 (FGFR4), platelet-derived growth factor receptor-beta (PDG-FRB), and fms-related tyrosine kinase-4 (FLT4). The genes and gene products associated with familial hemangiomas may be involved somatically in the more common sporadic cases.

Diminished production of human immunodeficiency virus type 1 in astrocytes results from inefficient translation of gag, env, and nef mRNAs despite efficient expression of Tat and Rev

Astrocytes infected with human immunodeficiency virus type 1 (HIV-1) produce only minimal quantities of virus. The molecular events that limit acute-phase HIV-1 infection of astrocytes were examined after inducing acute-phase replication by transfection with the pNL4-3 proviral plasmid. The levels of HIV-1 mRNA were similarly high in both astrocytes and HeLa cells, but astrocytes produced approximately 50-fold less supernatant p24 than HeLa cells. We found that diminished HIV-1 production in astrocytes resulted from inefficient translation of gag, env, and nef mRNAs that were efficiently transported to the cytoplasm. Tat- or Rev-dependent reporter constructs showed no defect in Tat or Rev function in astrocytes compared with HeLa cells. HIV-1 mRNAs were correctly spliced, but only Rev and Tat proteins were efficiently translated from their native mRNAs. Pulse-chase labelling and immunoblot experiments revealed no defect in protein processing, but levels of Gag, Env, or Nef protein expressed were dramatically reduced in astrocytes compared to HeLa cells. These results demonstrate that inefficient translation of HIV-1 structural proteins underlies the restricted infection of astrocytes. The efficient expression of functional Tat and Rev by astrocytes may contribute to HIV-1 neuropathogenesis.

Implementation of a computerized cardiovascular information system in a private hospital setting

BACKGROUND

The use of clinical databases improves quality of care, reduces operating costs, helps secure managed care contracts, and assists in clinical research. Because of the large physician input required to maintain these systems, private institutions have often found them difficult to implement. At LDS Hospital in Salt Lake City, Utah, we developed a cardiovascular information system (LDS-CIS) patterned after the Duke University Cardiovascular Database and designed for ease of use in a private hospital setting.

METHODS

Features of the LDS-CIS include concise single-page report forms, a relational database engine that is easily queried, automatic generation of final procedure reports, and merging of all data with the hospital's existing information system. So far, data from more than 14,000 patients have been entered.

RESULTS

LDS-CIS provides access to data for research to improve patient care. For example, by using data generated by LDS-CIS, the policy requiring surgical backup during percutaneous transluminal coronary angioplasty was eliminated, resulting in no increased patient risk while saving nearly $1 million in 1 year. LDS-CIS generates physician feedback reports documenting performance compared with peers. This physician self-evaluation has standardized and improved care. Information from LDS-CIS has been instrumental in securing and maintaining managed care contracts. LDS-CIS risk analysis provides physicians with outcomes data specific to their current patient's demographics and level of disease to assist in point of care decisions.

CONCLUSION

The use of LDS-CIS in the routine operations of LDS Hospital heart services has been found to be feasible, beneficial, and cost-effective.

Ketamine inhibits the proinflammatory cytokine-induced reduction of cardiac intracellular cAMP accumulation

The proinflammatory cytokines, including tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma), are increased in heart failure and sepsis, clinical conditions for which the IV anesthetic ketamine is useful. The proinflammatory cytokines cause beta-adrenergic receptor (betaAR) hypofunction secondary to reduced function of the enzyme adenylylcyclase (AC). In this study, we evaluated the effect of ketamine alone, TNF-alpha and IFN-gamma, and ketamine plus TNF-alpha and IFN-gamma, on isoproterenol (ISO, a betaAR agonist) and forskolin (FSK, an activator of AC)-induced intracellular accumulation of cAMP. An in vitro culture of a rat heart cell line (H9c2) was labeled with [3H]adenine to produce [3H]ATP, and we measured the intracellular accumulation of [3H]cAMP after stimulation with ISO or FSK to convert the [3H]ATP to [3H]cAMP. Pretreatment with either cytokine alone did not significantly affect ISO or FSK-induced intracellular cAMP accumulation, whereas the combination of TNF-alpha and IFN-gamma caused a significant (P < 0.05 compared with untreated cells) reduction. Pretreatment with ketamine caused a significant (P < 0.05 compared with untreated cells) increase in ISO or FSK-induced cAMP accumulation. Pretreatment of the H9c2 cells with ketamine, plus the combination of TNF-alpha and IFN-gamma, inhibited the reduction of ISO or FSK-induced intracellular cAMP accumulation caused by the proinflammatory cytokines alone. These results demonstrate that the combination of the proinflammatory cytokines TNF-alpha and IFN-gamma reduce poststimulation (ISO or FSK) intracellular cAMP accumulation. This action of the proinflammatory cytokines is consistent with the observation of betaAR hyporesponsiveness to betaAR agonist therapy in sepsis and heart failure. Ketamine augments the poststimulation cAMP accumulation in H9c2 cells while inhibiting the cytokine-induced reduction of cAMP accumulation. This may partly explain the improvement in cardiac function after ketamine use in clinical conditions known to have increased systemic levels of proinflammatory cytokines, such as sepsis and heart failure.

IMPLICATIONS

Tumor necrosis factor-alpha and interferon-gamma reduced poststimulation intracellular cAMP levels, whereas ketamine inhibits this action of the proinflammatory cytokines. Because cAMP is the second messenger for the beta-adrenergic receptor, this may be a mechanism for improved blood pressure and cardiac output in sepsis and heart failure after ketamine use.

Epicardial cardioverter-defibrillators do not cause postoperative arrhythmias. The CABG Patch Trial Investigators. Coronary Artery Bypass Graft

The CABG Patch Trial is a controlled, multicenter clinical trial that randomized high-risk patients undergoing coronary artery bypass grafting (CABG) to prophylactic implantation of an epicardial implantable cardioverter-defibrillator (ICD) or to no additional treatment, permitting a controlled evaluation of the effect of epicardial ICDs on the incidence of postoperative arrhythmias. We found no significant difference in the development of postoperative arrhythmias between patients who received epicardial ICDs and the control group treated with CABG alone.

Heart rate changes preceding ventricular ectopy in patients with ventricular tachycardia caused by reentry, triggered activity, and automaticity

OBJECTIVES

Although enhanced sympathetic tone is thought to be proarrhythmic and beta-blockade reduces the risk of sudden cardiac death in survivors of myocardial infarction, the role of the autonomic nervous system in triggering spontaneous ventricular ectopy and ventricular tachycardia (VT) has not been fully elucidated. The purpose of this study was to compare and contrast autonomic tone preceding spontaneous ventricular arrhythmias in patients with reentrant, triggered, and automatic forms of VT.

BACKGROUND

The prevailing model of reentrant VT is based on a triggering beat interacting with a fixed substrate. Within this model, cyclic fluctuations in autonomic tone comprise a "third factor" that may initiate the triggering extrasystoles as well as alter the substrate, facilitating perpetuation of tachycardia. Consistent with this model, adrenergic stimulation can facilitate the induction of reentrant arrhythmias as well as arrhythmias resulting from enhanced automaticity and those caused by triggered activity resulting from cyclic adenosine monophosphate-dependent delayed afterdepolarizations.

METHODS AND RESULTS

On the basis of the results at electrophysiologic study, 26 patients with coronary artery disease were identified as having reentrant VT, 11 were identified as having idiopathic VT caused by triggered activity, and 4 were identified as having idiopathic VT caused by enhanced automaticity. Each patient underwent 24-hour electrocardiographic monitoring, and the mean sinus R-R intervals immediately preceding each sinus beat as well as the 15 beats preceding sinus beats, premature ventricular contractions (VPCs), and complex ventricular ectopy (couplet/non-sustained VT) were computed. In addition, high-frequency heart rate variability was determined. Heart rate accelerated before spontaneous ventricular ectopy for all three arrhythmia mechanisms. R-R intervals preceding episodes of complex ventricular ectopy were significantly shorter than the corresponding intervals preceding single VPCs in patients with 'riggered VT [p=0.006 and 0.01, R-R(-1) and R-R(-15), respectively] and in those with reentrant VT (p=0.007 and p=0.05). There were no corresponding differences in high-frequency heart rate variability. R-R intervals preceding single VPCs were significantly shorter than the corresponding intervals preceding sinus beats in patients with automatic VT (p=0.0004 and 0.0001, respectively), which was accompanied by a small reduction in high-frequency heart rate variability (p=0.04).

CONCLUSIONS

Heart rate accelerates before spontaneous ventricular ectopy in patients with VT. The acceleration is disproportionate to parasympathetic withdrawal, implicating increased endogenous sympathetic tone in the genesis of spontaneous ventricular arrhythmias caused by all three electrophysiologic mechanisms: reentry, triggered activity, and automaticity.

Genetic regulation of Dermatophagoides pteronyssinus-specific IgE responsiveness: a genome-wide multipoint linkage analysis in families recruited through 2 asthmatic sibs. Collaborative Study on the Genetics of Asthma (CSGA)

BACKGROUND

Dermatophagoides pteronyssinus (Der p) is one of the most frequently implicated allergens in atopic diseases. Although HLA could play an important role in the development of the IgE response to the Der p allergens, genetic regulation by non-HLA genes influences certain HLA-associated IgE responses to complex allergens.

OBJECTIVE

To clarify genetic control for the expression of Der p-specific IgE responsiveness, we conducted a genome-wide search for genes influencing Der p-specific IgE antibody levels by using 45 Caucasian and 53 African American families ascertained as part of the Collaborative Study on the Genetics of Asthma (CSGA).

METHODS

Specific IgE antibody levels to the Der p crude allergen and to the purified allergens Der p 1 and Der p 2 were measured. Multipoint, nonparametric linkage analysis of 370 polymorphic markers was performed with the GENEHUNTER program.

RESULTS

The best evidence of genes controlling specific IgE response to Der p was obtained in 2 novel regions: chromosomes 2q21-q23 (P = .0033 for Caucasian subjects) and 8p23-p21 (P = .0011 for African American subjects). Three regions previously proposed as candidate regions for atopy, total IgE, or asthma also showed evidence for linkage to Der p-specific IgE responsiveness: 6p21 (P = .0064) and 13q32-q34 (P = 0.0064) in Caucasian subjects and 5q23-q33 (P = 0.0071) in African American subjects.

CONCLUSIONS

No single locus generated overwhelming evidence for linkage in terms of established criteria and guidelines for a genome-wide screening, which supports previous assertions of a heterogeneous etiology for Der p-specific IgE responsiveness. Two novel regions, 2q21-q23 and 8p23-p21, that were identified in this study merit additional study.

Kinetics and yield of singlet oxygen photosensitized by hypericin in organic and biological media

The spectroscopy and photophysics of the photosensitizer hypericin when in homogeneous solutions and when bound to liposomes were studied. Hypericin was found to partition efficiently into DMPC liposomes, with a binding constant of 58 (mg lipid/mL)-1. In these liposomes the singlet oxygen production quantum yield was 0.43 +/- 0.09. To determine the deactivation constant of singlet oxygen in lipid bilayers for the first time, we calculated extrapolated values from its quenching by DMPC and lecithin in homogeneous solutions and obtained decay times of 36.4 and 12.2 microseconds, respectively. We also measured the quenching of singlet oxygen, sensitized by hypericin in DMPC liposomes, by NaN3, diphenyl isobenzofuran and H2O:D2O mixtures and explained the results on the basis of singlet oxygen diffusing rapidly out of the lipid bilayer into the aqueous medium. The observed temperature effect on the lifetime of singlet oxygen of about 50% over a 15 degrees C range in liposome suspension contrasts with a 3% change in a homogeneous solution in 1-nonanol and is explained by the temperature effect on the diffusion out of the liposome. A strong pH effect was observed, indicating that the deprotonated species formed above about pH 10 is a much weaker photosensitizer of singlet oxygen than the native, protonated species.

Evaluation of C-reactive protein, an inflammatory marker, and infectious serology as risk factors for coronary artery disease and myocardial infarction

OBJECTIVES

We sought to test whether C-reactive protein (CRP) and seropositivity to any of three infectious agents are associated with angiographic coronary artery disease (CAD) and clinical myocardial infarction (MI).

BACKGROUND

CRP, an inflammatory marker, is reported to predict risk of MI. The stimulus for CRP is unknown but might include infection. Chlamydia pneumoniae, cytomegalovirus and Helicobacter pylori have been linked to risk of MI or CAD.

METHODS

Blood samples were collected from 363 patients undergoing coronary arteriography and tested for CRP and IgG titers to the infectious agents.

RESULTS

CRP was higher in patients with CAD (1.32 mg/dl [SE 0.22, n = 80] vs. 0.58 mg/dl [SE 0.11 mg/dl, n = 109], p = 0.004) and in those with MI (2.05 mg/dl [SE 0.36, n = 47] vs. 0.54 mg/dl [SE 0.08, n = 133], p = 0.0002) than in respective control subjects. Seropositivity for each agent was present in a high proportion of patients with CAD (58% to 77%) or MI (54% to 75%) as well as in control subjects (no CAD: 46% to 74%; no MI: 50% to 77%). However, subjects seropositive to both C. pneumoniae and H. pylori had an increased prevalence of CAD (odds ratio [OR] 2.6, p = 0.02) and MI (OR 2.0, p = 0.15) and tended to have higher CRP levels (1.07 mg/dl [SE 0.16]) than those seronegative to both infectious agents (0.53 mg/dl [SE 0.10], p = 0.06).

CONCLUSIONS

CRP is elevated in patients with CAD (more than twofold) and in those with MI (fourfold). Infectious serology is highly prevalent in both patients and control subjects. Seropositivity to both C. pneumoniae and H. pylori (but not one agent alone) may predict increased risk and may be associated with higher CRP levels. Infectious serology may be less predictive than previously suggested, but the cause of inflammation in CAD and MI deserves further study.

Multivariate associates of QT dispersion in patients with acute myocardial infarction: primacy of patency status of the infarct-related artery. TEAM-3 Investigators. Third trial of Thrombolysis with Eminase in Acute Myocardial Infarction

BACKGROUND

QT dispersion (QTd; QT interval maximum minus minimum) has been shown to reflect regional variations in ventricular repolarization and is increased in patients with life-threatening ventricular arrhythmias.

METHODS

To determine correlates of QTd in patients who had had myocardial infarction (MI), 207 patients (158 men, aged 57 +/- 11 years) with acute MI who were treated with alteplase or anistreplase within 2.7 +/- 0.9 hours of symptom onset were studied. Angiograms at a median of 27 hours after thrombolysis showed reperfusion (Thrombolysis in Myocardial Infarction grade > or =2) in 184 (88%) patients. QT was measured in 10 +/- 2 leads on discharge electrocardiograms with a computerized analysis program interfaced with a digitizer. Associations of QTd with 24 variables related to patient characteristics, acute MI, angiography, interventions, and radionuclide ventriculography were evaluated by univariate and multivariate regression.

RESULTS

Univariate associations with QTd (p < or = 0.10) were Thrombolysis in Myocardial Infarction flow grade 0/1 versus 2/3 (QTd = 75 +/- 33 msec vs 53 +/- 22 msec, p < 0.0001), minimal luminal diameter (p = 0.007), left ventricular ejection fraction at discharge (p = 0.007), reinfarction (p = 0.01), number of leads with ST elevation (p = 0.05), end-systolic volume at discharge (p = 0.04), time to peak creatine kinase (p = 0.06), and YST elevation (p = 0.10). Independent associates of QTd were Thrombolysis in Myocardial Infarction grade 0/1 versus 2/3 (p < 0.0001), reinfarction (p = 0.005), and ejection fraction (p = 0.02).

CONCLUSIONS

Successful thrombolysis is associated with less QTd in patients after acute MI. Our results support the hypothesis that QTd after MI depends on reperfusion status, reinfarction, and left ventricular function. Reduction in QTd may be an additional mechanism by which the benefit of thrombolytic therapy is realized.

Angiotensin-converting enzyme genotypes and risk for myocardial infarction in women

OBJECTIVES

We tested for an association between the angiotensin-converting enzyme (ACE) DD polymorphic genotype and myocardial infarction (MI) in a sample group composed exclusively of women.

BACKGROUND

The human ACE gene occurs with either an insertion (I allele) or a deletion (D allele) of a 287-base pair (bp) Alu element. Part of the variance in serum ACE levels may be accounted for by this polymorphism. Also, the DD genotype has been associated with an increased risk of MI in predominantly male populations. However, the risk in women is poorly defined.

METHODS

Genomic DNA was extracted from buffy coat blood using a phenol/chloroform method. Angiotensin-converting enzyme alleles were identified using primers to bracket the insertion region in intron 16. Amplification using polymerase chain reaction allowed identification of a 490-bp (I allele) or a 190-bp (D allele) product, or both.

RESULTS

Allelic and genotypic frequencies in control subjects were similar to those reported in mostly male populations, and frequencies of genotypes were in the Hardy-Weinberg equilibrium. In contrast, the distribution of genotypes in patients with MI diverged from the equilibrium. Specifically, DD genotypic frequency was increased in women with (n = 141) versus without (n = 338) a previous MI (39% vs. 29%, odds ratio [OR] 1.54, 95% confidence interval 1.02 to 2.32, p < 0.04). Risk was particularly increased in women <60 years old (OR 2.04, p < 0.05). In contrast, the DD genotype did not predict angiographic coronary artery disease.

CONCLUSIONS

Consistent with findings in male-dominated populations, a modest association of the ACE DD genotype with MI was found in women. The basis for this association requires further study.

Infection with Chlamydia pneumoniae accelerates the development of atherosclerosis and treatment with azithromycin prevents it in a rabbit model

BACKGROUND

Chlamydia pneumoniae infection has been associated with atherosclerosis by serological studies and detection of bacterial antigen within plaque. We sought to evaluate a possible causal role in an animal model.

METHODS AND RESULTS

Thirty New Zealand White rabbits were given three separate intranasal inoculations of either C pneumoniae (n = 20) or saline (n = 10) at 3-week intervals and fed chow enriched with a small amount (0.25%) of cholesterol. Immediately after the final inoculation, infected and control rabbits were randomized and begun on a 7-week course of azithromycin or no therapy. Three months after the final inoculation, rabbits were euthanatized and sections of thoracic aortas were blindly evaluated microscopically for maximal intimal thickness (MIT), percentage of luminal circumference involved (PLCI), and plaque area index (PAI) of atherosclerosis. Vascular chlamydial antigen was assessed by direct immunofluorescence. MIT differed among treatment groups (P=.009), showing an increase in infected rabbits (0.55 mm; SE = 0.15 mm) compared with uninfected controls (0.16 mm; SE = 0.06 mm) and with infected rabbits receiving antibiotics (0.20 mm; SE = 0.03 mm) (both P<.025), whereas MIT in infected/treated versus control rabbits did not differ. PLCI also tended to differ (P<.1) and PAI differed significantly (P<.01) among groups with a similar pattern. Chlamydial antigen was detected in 2 untreated, 3 treated, and 0 control animals.

CONCLUSIONS

Intranasal C pneumoniae infection accelerates intimal thickening in rabbits given a modestly cholesterol-enhanced diet. In addition, weekly treatment with azithromycin after infectious exposure prevents accelerated intimal thickening. These findings strengthen the etiologic link between C pneumoniae and atherosclerosis and should stimulate additional animal and human studies, including clinical antibiotic trials.

Footwall refrigeration along a detachment fault: implications for the thermal evolution of core complexes

Oxygen isotope compositions of epidote and quartz from chloritic breccias that underlie the detachment fault in the metamorphic core complex of the Whipple Mountains yielded quartz-epidote fractionations that range from 4.1 to 6.4 per mil and increase systematically toward the fault. These fractionations give mean temperatures that decrease from approximately 432 degrees C at 50 meters below the fault to approximately 350 degrees C at 12 meters below the fault. This extreme thermal gradient of 82 degrees C over 38 meters (2160 degrees C per kilometer) is best explained by advective heat extraction by means of circulating surface-derived fluids. Models of lithospheric extension consider only conductive cooling resulting from tectonic denudation and thus require revision to include fluid-induced fault-zone refrigeration.