Pharmacotherapy for erectile dysfunction

OBJECTIVE

To review current pharmacologic treatment options for erectile dysfunction.

METHODS

Relevant literatures from the past two decades regarding the following treatments were reviewed: intracavemous injection, topical therapy, transurethral therapy and oral drugs.

STUDY SELECTION

More than 125 originally identified articles were reviewed, and 45 were selected that especially addressed the stated purpose.

RESULTS

Among the pharmacologic treatment options available, intracavemous injection therapy remains the most effective although the drop-out rate is high. Topical creams and gels have not been very successful. Transurethral alprostadil can be more effective if a constriction device is applied at the base of the penis. Oral sildenafil has the highest patient acceptance rate although systemic side effects can be a major drawback.

CONCLUSIONS

Effective pharmacotherapies for ED of various etiologies are now available. However, proper evaluation of every patient should be performed before giving treatment so that a number of potentially life-threatening causes of erectile dysfunction would not be missed.

Prenyltransferase inhibitors block superoxide production by pulmonary vascular smooth muscle

We recently showed that the farnesyltransferase inhibitor FTI-277 blocks interleukin 1beta (IL-1beta)-induced nitric oxide production in pulmonary vascular smooth muscle cells (SMC), whereas the geranylgeranyltransferase inhibitor GGTI-298 enhances this effect. Here we show that IL-1beta and platelet-derived growth factor (PDGF) stimulate superoxide production by pulmonary vascular SMC and that this effect is blocked by both FTI-277 and GGTI-298, suggesting that farnesylated and geranylgeranylated proteins are required for superoxide production. We also show that FTI-277 and GGTI-298 block superoxide production stimulated by constitutively active mutant H-Ras. Furthermore, superoxide production by IL-1beta, PDGF factor, and constitutively activated Ras is blocked by diphenyleneiodonium, implicating NAD(P)H oxidase as the generating enzyme. Given the role of oxidant radicals in vascular reactivity and injury, the action of both FTI-277 and GGTI-298 in suppressing superoxide generation by an inflammatory cytokine as well as by a potent smooth muscle mitogen may be therapeutically useful.

Prognostic models based on literature and individual patient data in logistic regression analysis

Prognostic models can be developed with multiple regression analysis of a data set containing individual patient data. Often this data set is relatively small, while previously published studies present results for larger numbers of patients. We describe a method to combine univariable regression results from the medical literature with univariable and multivariable results from the data set containing individual patient data. This 'adaptation method' exploits the generally strong correlation between univariable and multivariable regression coefficients. The method is illustrated with several logistic regression models to predict 30-day mortality in patients with acute myocardial infarction. The regression coefficients showed considerably less variability when estimated with the adaptation method, compared to standard maximum likelihood estimates. Also, model performance, as distinguished in calibration and discrimination, improved clearly when compared to models including shrunk or penalized estimates. We conclude that prognostic models may benefit substantially from explicit incorporation of literature data.

Immunoglobulin M and G immunoblots in the diagnosis of parvovirus B19 infection

BACKGROUND AND PURPOSE

To identify parvovirus B19 infection by means of immunoglobulin (Ig) G and IgM immunoblots among immunocompetent patients who tested negative or had low-titer B19 IgM antibodies in enzyme-linked immunosorbent assays (ELISA).

METHODS

Serum samples were obtained from 20 patients with parvovirus B19 infection. Another 130 study subjects presumed to be without B19 infection (40 medical personnel and 90 prisoners) were also included. All sera from the patient and study groups tested positive for IgG or IgM with ELISA and were further evaluated using the immunoblot method. Detection of B19 DNA by nested polymerase chain reaction (PCR) was also performed on IgG and IgM positive sera.

RESULTS

IgM immunoblots disclosed one false positive IgM ELISA result in the patient group and three false positive results in the study group. In the patient group, four patients were in the latter stage of antibody response to B19 infection as suggested by the low titer of anti-B19 IgM, incomplete IgM immunoblots, with only a weak viral capsid protein VP-N reaction band, and fading but still strong reaction bands on IgG immunoblots. Strong reaction bands on IgG immunoblots comparable to these four patients were found in three of the 130 study group sera. Furthermore, B19 DNA was detected in three of the four patients and one of the three study subjects by means of nested-PCR. A serum sample from one study subject showed strong IgG but no IgM reactivity to viral capsid protein VP2; nested PCR identified B19 DNA in this serum sample.

CONCLUSIONS

Immunoblots and nested PCR should be applied in the diagnosis of B19 infection for patients with low-titer anti-B19 IgM tested by means of ELISA. For diagnosis of B19 infections in certain clinical entities such as chronic arthritis of recent onset and hydrops fetalis, B19 IgM antibodies may have disappeared but B19 infection can still be recognized by the intensity of the reaction bands on IgG immunoblots. The correlation between chronic B19 infection and persistence of antilinear VP2 epitopes requires further study.

A randomized study of the prevention of sudden death in patients with coronary artery disease. Multicenter Unsustained Tachycardia Trial Investigators

BACKGROUND

Empirical antiarrhythmic therapy has not reduced mortality among patients with coronary artery disease and asymptomatic ventricular arrhythmias. Previous studies have suggested that antiarrhythmic therapy guided by electrophysiologic testing might reduce the risk of sudden death.

METHODS

We conducted a randomized, controlled trial to test the hypothesis that electrophysiologically guided antiarrhythmic therapy would reduce the risk of sudden death among patients with coronary artery disease, a left ventricular ejection fraction of 40 percent or less, and asymptomatic, unsustained ventricular tachycardia. Patients in whom sustained ventricular tachyarrhythmias were induced by programmed stimulation were randomly assigned to receive either antiarrhythmic therapy, including drugs and implantable defibrillators, as indicated by the results of electrophysiologic testing, or no antiarrhythmic therapy. Angiotensin-converting-enzyme inhibitors and beta-adrenergic-blocking agents were administered if the patients could tolerate them.

RESULTS

A total of 704 patients with inducible, sustained ventricular tachyarrhythmias were randomly assigned to treatment groups. Five-year Kaplan-Meier estimates of the incidence of the primary end point of cardiac arrest or death from arrhythmia were 25 percent among those receiving electrophysiologically guided therapy and 32 percent among the patients assigned to no antiarrhythmic therapy (relative risk, 0.73; 95 percent confidence interval, 0.53 to 0.99), representing a reduction in risk of 27 percent). The five-year estimates of overall mortality were 42 percent and 48 percent, respectively (relative risk, 0.80; 95 percent confidence interval, 0.64 to 1.01). The risk of cardiac arrest or death from arrhythmia among the patients who received treatment with defibrillators was significantly lower than that among the patients discharged without receiving defibrillator treatment (relative risk, 0.24; 95 percent confidence interval, 0.13 to 0.45; P<0.001). Neither the rate of cardiac arrest or death from arrhythmia nor the overall mortality rate was lower among the patients assigned to electrophysiologically guided therapy and treated with antiarrhythmic drugs than among the patients assigned to no antiarrhythmic therapy.

CONCLUSIONS

Electrophysiologically guided antiarrhythmic therapy with implantable defibrillators, but not with antiarrhythmic drugs, reduces the risk of sudden death in high-risk patients with coronary disease.

Effect of the implantable atrial defibrillator on the natural history of atrial fibrillation

INTRODUCTION

The purpose of our study was to evaluate the effect of repeated cardioversion with an implantable atrial defibrillator on the clinical outcome of patients with atrial fibrillation.

METHODS AND RESULTS

The effects of the implantable atrial defibrillator on the total duration of atrial fibrillation, number of atrial fibrillation recurrences, and left atrial size were evaluated prospectively in 16 patients with atrial fibrillation (13 men and 3 women; mean age 58 +/- 11 years). Seven patients had no cardiovascular disease, 5 patients had hypertension, 3 patients had coronary heart disease, and 1 patient had congenital heart disease. Eight patients had paroxysmal atrial fibrillation for a mean duration of 80 +/- 61 months, and eight patients had persistent atrial fibrillation for a mean duration of 68 +/- 119 months. Except for one patient who received digoxin throughout the study, all patients received the same Class I or III antiarrhythmic agent throughout the study. The implantable atrial defibrillator successfully converted 50 (93%) of 54 spontaneous episodes of atrial fibrillation in 12 patients. During the initial 3 months of clinical follow-up, the atrial defibrillator documented 261 +/- 270 hours of atrial fibrillation compared with 126 +/- 172 hours (P = 0.01) during the subsequent 3 months. The left atrial size decreased from 4.4 +/- 0.7 cm at the time of atrial defibrillator implantation to 4.1 +/- 0.6 cm (P = 0.02) 6 months later. The number of atrial fibrillation recurrences did not change. These findings were observed in the absence of changes in drug therapy. No complications were observed.

CONCLUSION

Restoration and maintenance of sinus rhythm in patients with atrial fibrillation by repeated cardioversion with an implantable atrial defibrillator was associated with a reduction in the total arrhythmia duration and a reduction in left atrial size. These results suggest that maintenance of sinus rhythm with the atrial defibrillator may reverse the remodeling process associated with atrial fibrillation.

Autologous blood use in percutaneous nephrolithotomy

OBJECTIVES

Preoperative autologous blood (AUB) donation has decreased patient exposure to allogenic blood (ALB) products and associated infectious risk. The risk of contracting hepatitis C and human immunodeficiency virus is 1 in 103,000 and 1 in 678,000, respectively, after receiving 1 U ALB. Elective surgical procedures require surgeons to offer preoperative AUB donation in California. Unused AUB is discarded. We report our use of AUB obtained for percutaneous nephrolithotomy.

METHODS

A retrospective study of 144 consecutive patients who underwent 193 percutaneous nephrolithotomies between January 1994 and April 1998 at one of four teaching hospitals at the University of California, San Francisco was performed. Preoperative AUB donation, transfusion rates, hemoglobin levels, blood use, and costs were analyzed.

RESULTS

Ninety-six units of blood were collected from 63 patients (44%) and were available for 70 procedures (36%). The overall transfusion rate per procedure was 7%, with 13 patients receiving a total of 24 U, 7 AUB and 17 ALB. Eighty-nine units (92.7%) of AUB were discarded, and the transfusion rate in donors and nondonors was similar. There was no significant difference in preoperative hemoglobin or operative blood loss between donors and nondonors. The 13 transfused patients had a lower preoperative hemoglobin ( 11.5 versus 12.8 g/dL; P = 0.029) and higher operative blood loss as measured by hemoglobin level (3.2 versus 1.6 g/dL; P <0.001). Blood bank charges for ALB and AUB were $ 119/U and $244 to $498/U, respectively, depending on transportation and thawing charges.

CONCLUSIONS

Routine preoperative blood donation adds substantial cost for minimal benefit, given the low infectious risk of ALB and the two- to fourfold higher cost of AUB. In our series, women had an increased incidence of blood transfusion compared with men. AUB donation may provide peace of mind but is rarely used and is discarded 93% of the time.

Effect of adenosine and verapamil in catecholamine-induced accelerated atrioventricular junctional rhythm: insights into the underlying mechanism

Accelerated AV junctional rhythm is postulated to be due to enhanced automaticity of a high AV junctional focus. The adenosine response of this rhythm was tested in 17 patients (7 males, 12-83 years). The indications of electrophysiology study were nonspecific palpitation (n = 5), unexplained syncope (n = 6), postablation of accessory pathways (n = 4), and postmodification of AV nodal reentry tachycardia (n = 2). The sinus node and AV nodal functions were normal. Pacing and programmed electrical stimulation failed to induce any arrhythmia at baseline. The accelerated junctional rhythm (cycle length = 553 +/- 134 ms) was initiated spontaneously in all patients after isoproterenol infusion (1-2 micrograms/min). It was not suppressible by overdrive pacing. Cessation of isoproterenol infusion terminated the rhythm in all patients. Adenosine (6 mg) reproducibly terminated the accelerated junctional rhythm in all patients. In six patients, adenosine suppressed the junctional rhythm without producing AV nodal block. In the other 11 patients, the junctional rhythm was terminated prior to the occurrence of AV nodal block. Verapamil was tested in ten patients and 5 mg of intravenous verapamil terminated the junctional rhythm in all patients. In conclusion, the mechanism of catecholamine-induced accelerated AV junctional rhythm is most likely enhanced automaticity, and catecholamine-induced accelerated AV junctional automaticity is sensitive to adenosine and verapamil. Adenosine appears to have differential effects on catecholamine-enhanced AV junctional automaticity and AV nodal conduction. This suggests that, under catecholamine stimulation, adenosine may have different mechanisms of action on AV nodal conduction and automaticity.

Prediction of sustained ventricular tachycardia inducible by programmed stimulation in patients with coronary artery disease. Utility of clinical variables

BACKGROUND

Cardiologists often use clinical variables to determine the need for electrophysiological studies to stratify patients for risk of sudden death. It is not clear whether this is rational in patients with coronary artery disease, left ventricular dysfunction, and nonsustained ventricular tachycardia.

METHODS AND RESULTS

We analyzed the first 1721 patients enrolled in the Multicenter UnSustained Tachycardia Trial to determine whether clinical variables could predict which patients would have inducible sustained monomorphic ventricular tachycardia. The rate of inducibility of sustained ventricular tachycardia was significantly higher in patients with a history of myocardial infarction and in men compared with women. There was a progressively increased rate of inducibility with increasing numbers of diseased coronary arteries. There was a significantly lower rate of inducibility in patients with prior coronary artery bypass surgery and in patients who also had noncoronary cardiac disease. The rate of inducibility was higher in patients of white race, patients with recent (</=6 weeks) angina, left ventricular dyskinesis, and in patients with greater numbers of fixed thallium defects. Inducibility was more likely in patients who had a prior myocardial infarction complicated by congestive heart failure, ventricular tachycardia, or fibrillation </=48 hours after the onset of infarction. Although these associations are statistically significant, the accuracy of the clinical variables in discriminating between patients with and those without inducible ventricular tachycardia is only modest (receiver operator characteristic area <0.70).

CONCLUSIONS

Multiple clinical variables are independently associated with inducible sustained ventricular tachycardia. However, they have limited utility to guide clinical decisions regarding the use of electrophysiological testing for risk stratification in this patient population.

Acute coronary syndromes in the GUSTO-IIb trial: prognostic insights and impact of recurrent ischemia. The GUSTO-IIb Investigators

BACKGROUND

Recurrent ischemia after an acute coronary syndrome portends an unfavorable outcome and has major resource-use implications. This issue has not been studied systematically among the spectrum of patients with acute coronary presentations, encompassing those with and without ST-segment elevation.

METHODS AND RESULTS

We assessed the 1-year prognosis of the 12 142 patients enrolled in the GUSTO-IIb trial by the presence (n=4125) or absence (n=8001) of ST-segment elevation. This latter group was further categorized into those with baseline myocardial infarction (n=3513) or unstable angina (n=4488). We also assessed the incidence of recurrent ischemia and its impact on outcomes. Recurrent ischemia was significantly rarer in those with ST-segment elevation (23%) than in those without (35%; P<0.001). Mortality at 30 days was greater among patients with ST-segment elevation (6.1% versus 3.8%; P<0.001) but less so at 6 months; by 1 year, mortality did not differ significantly (9.6% versus 8.8%). Patients with non-ST-segment-elevation infarction had higher rates of reinfarction at 6 months (9.8% versus 6.2%) and higher 6-month (8.8% versus 5.0%) and 1-year mortality rates (11.1% versus 7.0%) than such patients who had unstable angina.

CONCLUSIONS

Refractory ischemia was associated with an approximate doubling of mortality among patients with ST-segment elevation and a near tripling of risk among those without ST elevation. This study highlights not only the substantial increase in late mortality and reinfarction with non-ST-segment-elevation infarction but also the opportunities for better triage and application of therapeutic strategies for patients with recurrent ischemia.

Value of serial troponin T measures for early and late risk stratification in patients with acute coronary syndromes. The GUSTO-IIa Investigators

BACKGROUND

The baseline cardiac troponin T (cTnT) level strongly predicts short-term mortality in acute coronary syndromes, but the added value of later measures to predict short- and long-term outcome and in the context of baseline clinical characteristics is unclear.

METHODS AND RESULTS

Relations between baseline, peak, and 8- and 16-hour (late) cTnT results and outcomes were assessed in 734 patients in a GUSTO-IIa substudy. Proportional-hazards models assessed the prognostic information gained from late cTnT when added to a mortality model containing the baseline cTnT result and clinical factors. At baseline, 260 patients were cTnT-positive (>0.1 ng/mL), 323 became positive later, and 151 remained negative (</=0.1 ng/mL). Mortality at 30 days was 10% in the baseline-positive group, 5% in late-positive patients, and 0% in negative patients. After adjustment for baseline characteristics, any positive cTnT result predicted 30-day mortality (baseline, chi2=8.96, P=0.0113; 8-hour, chi2=6.51, P=0.0107; 16-hour, chi2=8.40, P=0.0038). Both the 8- and the 16-hour results added to the strength of the baseline result (baseline+8-hour, chi2=12.04, P=0.0072; baseline+16-hour, chi2=13.52, P=0.0036). Only age and ST-segment elevation were stronger predictors of 30-day mortality than baseline cTnT; results were similar for prediction of 1-year mortality. Most of the mortality difference between cTnT-positive and -negative patients occurred within the first 30 days.

CONCLUSIONS

The cTnT level is a strong, independent predictor of short-term outcome in acute coronary syndromes. The addition of later samples to a baseline level is useful to evaluate the risk of serious cardiac events.

In vitro bovine ciliary body/epithelium in a small continuously perfused Ussing type chamber

Our goal is to assess the viability of an in vitro preparation of bovine ciliary body/epithelium (CBE) in a small volume Ussing-type chamber. A new small volume Ussing-type chamber with continuous perfusion was developed for bovine CBE. The trans-CBE electrical parameters were monitored and the electrical responses of the CBE to ouabain (1 and 0.01 mM) were recorded. The trans-CBE fluxes of [14C]-L-ascorbate and [3H]-L-glucose were also studied. The bovine CBE preparation was stable inside the chamber in terms of its potential difference (PD), short circuit current (SCC) and trans-CBE resistance. They were -0.51+/-0.05 mV (aqueous side negative), -5.43+/-0.04 microAcm-2 and 94+/-2 Q.cm2 (mean s.e.m., n=35), respectively. The preparation hyperpolarised when 0.01 mM ouabain was administered to the aqueous side, depolarised when ouabain was applied to the stromal side. [3H]-L-glucose diffusion was about 74 nEq h(-1)cm(-2) in either direction (n=12). Taking the area magnification factor of the CBE into consideration, the diffusional L-glucose flux across the bovine CBE was comparable to other tight epithelia. A significant net ascorbate flux (0.26+/-0.05 nEq h(-1)cm(-2), n=4, p<0.01) was found in the stroma to aqueous direction. We have developed a viable in vitro bovine CBE preparation which was (1) electrically stable, (2) responsive to ouabain, (3) tight to L-glucose diffusion, and (4) capable of actively secreting ascorbate. A net trans-CBE chloride transport (0.81+/-0.30 microEq h(-1)cm(-2), n=12, p=0.01) from stromal to aqueous side was found in the present in vitro model under short-circuited conditions.

Chloride and sodium transport across bovine ciliary body/epithelium (CBE)

PURPOSE

To study the chloride and sodium ion transports across the bovine ciliary body/epithelium (CBE) by a modified Ussing-Zerahn type chamber.

METHODS

Isolated bovine CBE preparations were mounted in a modified Ussing-type chamber and the transepithelial electrical parameters were monitored. The inward (stroma to aqueous) and outward (aqueous to stroma) fluxes of 36[Cl] chloride and 22[Na] sodium ions across the CBE were measured under short-circuited conditions. The effect of 0.1 mM of furosemide and bumetanide on the chloride transport were studied.

RESULTS

The potential difference (PD), the resistance and the short-circuit current (SCC) across the isolated bovine ciliary body were found to be -0.20+/-0.01 mV (aqueous negative), 75+/-1 omegacm2 and -2.70+/-0.17 microAcm(-2) (mean+/-SEM, n=50) respectively. A statistically significant net inward chloride ion flux of 1.12+/-0.41 microEq h(-1)cm(-2) (p < 0.01) was found (n=15). The net chloride transport was abolished when 0.1 mM furosemide (82% inhibition) and 0.1 mM bumetanide (100% inhibition) were applied bilateral. No significant net sodium ion flux was detected.

CONCLUSIONS

Electrolyte and fluid transport across the bovine CBE may be via a bumetanide and furosemide-sensitive chloride transport mechanism. The Na-K-2Cl cotransporter plays a significant role in the trans-CBE chloride transport. The net chloride flux/current was about 12 times higher than the measured SCC, suggesting that the chloride ion transport may be coupled to other ion species.

Atenolol use and clinical outcomes after thrombolysis for acute myocardial infarction: the GUSTO-I experience. Global Utilization of Streptokinase and TPA (alteplase) for Occluded Coronary Arteries

OBJECTIVES

We assessed the use and effects of acute intravenous and later oral atenolol treatment in a prospectively planned post hoc analysis of the GUSTO-I dataset.

BACKGROUND

Early intravenous beta blockade is generally recommended after myocardial infarction, especially for patients with tachycardia and/or hypertension and those without heart failure.

METHODS

Besides one of four thrombolytic strategies, patients without hypotension, bradycardia or signs of heart failure were to receive atenolol 5 mg intravenously as soon as possible, another 5 mg intravenously 10 min later and 50 to 100 mg orally daily during hospitalization. We compared the 30-day mortality of patients given no atenolol (n=10,073), any atenolol (n=30,771), any intravenous atenolol (n=18,200), only oral atenolol (n=12,545) and both intravenous and oral drug (n=16,406), after controlling for baseline differences and for early deaths (before oral atenolol could be given).

RESULTS

Patients given any atenolol had a lower baseline risk than those not given atenolol. Adjusted 30-day mortality was significantly lower in atenolol-treated patients, but patients treated with intravenous and oral atenolol treatment vs. oral treatment alone were more likely to die (odds ratio, 1.3; 95% confidence interval, 1.0 to 1.5; p=0.02). Subgroups had similar rates of stroke, intracranial hemorrhage and reinfarction, but intravenous atenolol use was associated with more heart failure, shock, recurrent ischemia and pacemaker use than oral atenolol use.

CONCLUSIONS

Although atenolol appears to improve outcomes after thrombolysis for myocardial infarction, early intravenous atenolol seems of limited value. The best approach for most patients may be to begin oral atenolol once stable.

Estrogen treatment induces elevated expression of HMG1 in MCF-7 cells

The high mobility group (HMG) 1 protein is a highly conserved and ubiquitous chromosomal protein found enriched in active chromatin. In this study, we have investigated the effect of estrogen on the expression of the human high mobility group protein HMG1 gene and found that the HMG1 mRNA level in MCF-7 cells was sharply increased 2.5-fold after 30 min of estrogen treatment. Under continuous estrogen treatment, the HMG1 mRNA level decreased to a 1.5 times that of the basal level at 90 min and remained at this elevated level under estrogen treatment for up to 24 h. These results support the recent finding by Verrier et al. (C.S. Verrier, 1997, Mol. Endocrinol. 11, 1009-1019) that HMG1 promotes the binding of the estrogen receptor to the estrogen response element and further reinforce our believe that HMG1 plays a significant role in estrogen-induced gene expression.

Higher T-wave amplitude associated with better prognosis in patients receiving thrombolytic therapy for acute myocardial infarction (a GUSTO-I substudy). Global Utilization of Streptokinase and Tissue plasminogen Activator for Occluded Coronary Arteries

Increased T-wave amplitude is one of the earliest electrocardiographic (ECG) changes following coronary artery occlusion. Therefore, higher T waves in the presenting electrocardiogram should represent earlier time to treatment and thus be associated with lower mortality following thrombolytic therapy. However, T-wave amplitude has never been evaluated as a prognostic marker in this setting. We examined clinical outcomes in 3,317 patients with acute myocardial infarction (AMI) who underwent thrombolysis in the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO-I) Study. Patients were classified as either those with high T waves or those with low T waves. Higher T waves were defined as those >98th percentile of the upper limit of normal. T-wave amplitude was also evaluated as a continuous variable according to infarct location (maximum T-wave amplitude) and as the amount of excess T-wave amplitude above normal (excess T-wave amplitude). Patients with higher T waves had lower 30-day mortality than those without (5.2% vs 8.6%, p = 0.001) and were less likely to develop congestive heart failure (15% vs 24%, p <0.001) or cardiogenic shock (6.1% vs 8.6%, p = 0.023). Higher maximum T-wave amplitude and excess T-wave amplitude were predictive of lower 30-day mortality (chi-square = 67, p <0.001 and chi-square = 33, p <0.001, respectively). These differences remain significant after controlling for other prognostic baseline ECG variables. In addition, T-wave amplitude added prognostic significance after controlling for time to treatment. T-wave amplitude, an often-overlooked component of the electrocardiogram, can add significant prognostic information in initial evaluation of patients with AMI.

Multiple atrioventricular nodal pathways in humans: electrophysiologic demonstration and characterization

INTRODUCTION

Multiple AV nodal pathway physiology can be demonstrated in certain patients with clinical AV reentrant tachycardia.

METHODS AND RESULTS

Evidence suggesting multiple AV nodal pathway conduction was present in seven (two males; age range 15 to 75 years) of 78 patients (9%) who underwent electrophysiologic studies for AV nodal tachycardia. The presence of two discrete discontinuities in the AV nodal conduction curves suggested triple AV nodal pathway conduction. Detailed mapping of their retrograde atrial activation sequence was performed along the tricuspid annulus from the coronary sinus ostium to the His-bundle electrogram recording site. Three zones (anterior, middle, and posterior) correspond to the upper, middle, and lower third of the triangle of Koch, respectively. The fast pathway exits were determined as anterior (4/7) or middle (3/7), the intermediate pathway exits as middle (4/7) or posterior (3/7), and the slow pathway exits as middle (1/7) or posterior (6/7). Other evidence suggesting multiple AV nodal pathway conduction includes: (1) triple ventricular depolarizations from a single atrial impulse; (2) sequential dual ventricular echoes; (3) spontaneous transformation between the slow-fast and fast-slow forms of AV nodal reentrant tachycardia; and (4) persistent cycle length alternans during AV nodal reentrant tachycardia. In four patients, all three pathways were shown to be involved in AV nodal echoes or reentrant tachycardia.

CONCLUSION

Multiple AV nodal pathways are not uncommon and can be identified by careful electrophysiologic elucidation and mapping technique.

Clinical determinants of mortality in patients with angiographically diagnosed ischemic or nonischemic cardiomyopathy

OBJECTIVES

We sought to characterize the clinical determinants of mortality in patients with angiographically diagnosed ischemic or nonischemic cardiomyopathy.

BACKGROUND

Patients with ischemic cardiomyopathy may have a worse prognosis than patients with nonischemic cardiomyopathy. Few studies have assessed the effect of ischemic versus nonischemic etiology on outcomes.

METHODS

We analyzed prospectively collected data on 3,787 patients with a left ventricular ejection fraction < or = 40% who underwent coronary angiography. Patients were considered to have ischemic cardiomyopathy (n = 3,112) if they had a history of myocardial infarction, percutaneous transluminal coronary angioplasty, coronary artery bypass graft surgery or at least one major epicardial coronary artery with > or = 75% stenosis; all others were considered to have nonischemic cardiomyopathy (n = 675).

RESULTS

The median age, ejection fraction and proportion of patients with New York Heart Association functional class III or IV symptoms for the nonischemic and ischemic groups were 55 years versus 63 years, 27% versus 32% and 57% versus 25%, respectively. After adjustment for baseline clinical risk factors and presenting characteristics, ischemic etiology remained an important independent predictor of 5-year mortality (p < 0.0001). The extent of coronary artery disease was a better predictor of survival than ischemic or nonischemic etiology (log likelihood chi-square 700 vs. 675, respectively).

CONCLUSIONS

Ischemic etiology is a significant independent predictor of mortality in patients with cardiomyopathy. However, the extent of coronary artery disease contributes more prognostic information than the clinical diagnosis of ischemic or nonischemic cardiomyopathy. Further research is needed to refine the clinical definition of ischemic cardiomyopathy so that physicians can appropriately prescribe treatment and accurately predict outcome.

Complete amino acid sequence of ananain and a comparison with stem bromelain and other plant cysteine proteases

The amino acid sequences of ananain (EC3.4.22.31) and stem bromelain (3.4.22.32), two cysteine proteases from pineapple stem, are similar yet ananain and stem bromelain possess distinct specificities towards synthetic peptide substrates and different reactivities towards the cysteine protease inhibitors E-64 and chicken egg white cystatin. We present here the complete amino acid sequence of ananain and compare it with the reported sequences of pineapple stem bromelain, papain and chymopapain from papaya and actinidin from kiwifruit. Ananain is comprised of 216 residues with a theoretical mass of 23464 Da. This primary structure includes a sequence insert between residues 170 and 174 not present in stem bromelain or papain and a hydrophobic series of amino acids adjacent to His-157. It is possible that these sequence differences contribute to the different substrate and inhibitor specificities exhibited by ananain and stem bromelain.

Patient-specific predictions of outcomes in myocardial infarction for real-time emergency use: a thrombolytic predictive instrument

BACKGROUND

Thrombolytic therapy can be life-saving in patients with acute myocardial infarction. However, if given too late or insufficiently selectively, it may provide little benefit but still cause serious complications and incur substantial costs.

OBJECTIVE

To develop a thrombolytic predictive instrument for real-time use in emergency medical service settings that could 1) identify patients likely to benefit from thrombolysis and 2) facilitate the earliest possible use of this therapy.

DESIGN

Creation and validation of logistic regression-based predictive instruments based on secondary analysis of clinical data.

PATIENTS

4911 patients who had acute myocardial infarction and ST-segment elevation on electrocardiogram; 3483 received thrombolytic therapy.

MEASUREMENTS

Data were obtained from 13 major clinical trials and registries and directly from medical records, including electrocardiograms obtained at presentation. Input variables include presenting clinical and electrocardiography features; predictive models generate probabilities for acute (30-day) mortality if and if not treated with thrombolysis, 1-year mortality rates if and if not treated with thrombolysis, cardiac arrest if and if not treated with thrombolysis, thrombolysis-related intracranial hemorrhage, and thrombolysis-related major bleeding episode requiring transfusion. Together, these models constitute the thrombolytic predictive instrument.

RESULTS

The predictive models generated the following mean predictions for patients in the Thrombolytic Predictive instrument Database: 30-day mortality rate, 7.1%; 1-year mortality rate, 10.9%; rate of cardiac arrest, 3.7%; rate of thrombolysis-related intracranial hemorrhage. 0.6%; and rate of other thrombolysis-related major bleeding episodes, 5.0%. They discriminated with between persons having and those not having the predicted outcome; areas under the receiver-operating characteristic (ROC) curve were between 0.77 and 0.84 for the five outcomes. Calibration between each instrument's predicted and observed served rates was excellent. Validation of the predictive instruments of 30-day and 1-year mortality, done on a separate test dataset, yielded areas under the ROC curve of 0.76 for each

CONCLUSIONS

After the basic features of a clinical presentation are entered into a computerized electrocardiograph, the predictions of the thrombolytic predictive instrument can be printed on the electrocardiogram report. This decision aid may facilitate earlier and more appropriate use of thrombolytic therapy in patients with acute myocardial infarction.

Strategies for diagnosing HIV-1 infection in atypical Western blots

The Western blot (WB) has long been used to confirm positive ELISAs for diagnosing HIV-1 infections. However, some WB patterns may result in "indeterminate" or controversial reports thus impeding early diagnoses or accurate diagnoses. The interpretation of HIV-1 WB has no "gold standard" criterion. Incomplete antibody profiles on WB strips can be interpreted as positive or indeterminate according to different criteria. The possibility of HIV-2 infection was further checked in these serum samples. However, no reactivity to synthetic peptide of HIV-2 gp36 had been found. Serial WB analyses are important for attaining early diagnoses of HIV-1 infections as well as for evaluating clinical stages. Temporal changes on WB patterns of serial serum samples provide the evidence of seroconversion in individuals with risk behaviours and indeterminate WB. In late stage of HIV-1 infection, the reactivity to gag, pol and env antigen groups may decrease and result in indeterminate WB. We propose to diagnose HIV-1 infection and to differentiate the infection of HIV-1 from HIV-2 in these cases by using nested polymerase chain reaction (PCR) to demonstrate the presence of HIV-1 specific vpu gene.

Incidence and predictors of bleeding after contemporary thrombolytic therapy for myocardial infarction. The Global Utilization of Streptokinase and Tissue Plasminogen activator for Occluded coronary arteries (GUSTO) I Investigators

BACKGROUND

Although the benefit of thrombolytic therapy in reducing mortality in acute myocardial infarction is well established, the types of bleeding and risk factors for bleeding are less well described in large trials.

METHODS AND RESULTS

We analyzed the baseline characteristics, outcomes, and incidence of bleeding by location, severity, and treatment assignment among 41,021 patients in the GUSTO-I trial of thrombolysis for acute myocardial infarction. Of the 40,903 patients for whom there were complete data, 1.2% suffered severe bleeding and 11.4% experienced moderate hemorrhage at a variety of sites. The most common sources of bleeding were procedure related. The thrombolytic regimen was strongly related to the incidence of bleeding; comparatively more bleeding was seen with the therapies of streptokinase plus intravenous heparin and the streptokinase and tissue plasminogen activator plus intravenous heparin combination. In multivariate analysis, the four most powerful independent predictors of hemorrhage were older age, lighter body weight, female sex, and African ancestry; they remained the most important predictors of bleeding when multivariate analysis was performed on patients who did not undergo invasive procedures. The presence of serious hemorrhage was associated with other undesirable outcomes (recurrent events, left ventricular dysfunction, arrhythmia, or stroke).

CONCLUSIONS

Important predictors of bleeding in this population are increased age, lighter weight, female sex, African ancestry, and experiencing invasive procedures. Other nonhemorrhagic adverse clinical outcomes were associated with moderate and severe bleeding, which was in turn associated with increased length of hospital stay and mortality at 30 days.