Colchicine and high-intensity rosuvastatin in the treatment of non-critically ill patients hospitalised with COVID-19: a randomised clinical trial

OBJECTIVE

To evaluate the effect of colchicine and high-intensity rosuvastatin in addition to standard of care on the progression of COVID-19 disease in hospitalised patients.

DESIGN

A pragmatic, open-label, multicentre, randomised controlled trial conducted from October 2020 to September 2021. Follow-up was conducted at 30 and 60 days. The electronic medical record was used at all stages of the trial including screening, enrolment, randomisation, event ascertainment and follow-up.

SETTING

Four centres in the Yale New Haven Health System.

PARTICIPANTS

Non-critically ill hospitalised patients with COVID-19.

INTERVENTIONS

Patients were randomised 1:1 to either colchicine plus high-intensity rosuvastatin in addition to standard of care versus standard of care alone. Assigned treatment was continued for the duration of index hospitalisation or 30 days, whichever was shorter.

PRIMARY AND SECONDARY OUTCOME MEASURES

The prespecified primary endpoint was progression to severe COVID-19 disease (new high-flow or non-invasive ventilation, mechanical ventilation, need for vasopressors, renal replacement therapy or extracorporeal membrane oxygenation, or death) or arterial/venous thromboembolic events (ischaemic stroke, myocardial infarction, deep venous thrombosis or pulmonary embolism) evaluated at 30 days.

RESULTS

Among the 250 patients randomised in this trial (125 to each arm), the median age was 61 years, 44% were women, 15% were Black and 26% were Hispanic/Latino. As part of the standard of care, patients received remdesivir (87%), dexamethasone (92%), tocilizumab (18%), baricitinib (2%), prophylactic/therapeutic anticoagulation (98%) and aspirin (91%). The trial was terminated early by the data and safety monitoring board for futility. No patients were lost to follow-up due to electronic medical record follow-up. There was no significant difference in the primary endpoint at 30 days between the active arm and standard of care arm (15.2% vs 8.8%, respectively, p=0.17).

CONCLUSIONS

In this small, open-label, randomised trial of non-critically ill hospitalised patients with COVID-19, the combination of colchicine and rosuvastatin in addition to standard of care did not appear to reduce the risk of progression of COVID-19 disease or thromboembolic events, although the trial was underpowered due to a lower-than-expected event rate. The trial leveraged the power of electronic medical records for efficiency and improved follow-up and demonstrates the utility of incorporating electronic medical records into future trials.

TRIAL REGISTRATION

NCT04472611.

Design and rationale of the colchicine/statin for the prevention of COVID-19 complications (COLSTAT) trial

Background

Despite improvement in the standard of care (SOC) for hospitalized COVID-19 patients, rates of morbidity and mortality remain high. There continues to be a need for easily available and cost-effective treatments. Colchicine and rosuvastatin are both safe and well-studied medications with anti-inflammatory and other pleiotropic effects that may provide additional benefits to hospitalized COVID-19 patients.

Methods and results

The Colchicine/Statin for the Prevention of COVID-19 Complications (COLSTAT) trial is a pragmatic, open-label, multicenter, randomized trial comparing the combination of colchicine and rosuvastatin in addition to SOC to SOC alone in hospitalized COVID-19 patients. Four centers in the Yale New Haven Health network will enroll a total of 466 patients with 1:1 randomization. The trial will utilize the electronic health record (Epic® Systems, Verona, Wisconsin, USA) at all stages including screening, randomization, intervention, event ascertainment, and follow-up. The primary endpoint is the 30-day composite of progression to severe COVID-19 disease as defined by the World Health Organization ordinal scale of clinical improvement and arterial/venous thromboembolic events. The secondary powered endpoint is the 30-day composite of death, respiratory failure requiring intubation, and myocardial injury.

Conclusions

The COLSTAT trial will provide evidence on the efficacy of repurposing colchicine and rosuvastatin for the treatment of hospitalized COVID-19 patients. Moreover, it is designed to be a pragmatic trial that will demonstrate the power of using electronic health records to improve efficiency and enrollment in clinical trials in an adapting landscape.

Clinical Trial Registration: NCT04472611 (https://clinicaltrials.gov/ct2/show/NCT04472611).

Fast-relaxing cardiomyocytes exert a dominant role in the relaxation behavior of heterogeneous myocardium

Substantial variation in relaxation rate exists among cardiomyocytes within small volumes of myocardium; however, it is unknown how this variability affects the overall relaxation mechanics of heart muscle. In this study, we sought to modulate levels of cellular heterogeneity in a computational model, then validate those predictions using an engineered heart tissue platform. We formulated an in silico tissue model composed of half-sarcomeres with varied relaxation rates, incorporating single-cell cardiomyocyte experimental data. These model tissues randomly sampled relaxation parameters from two offset distributions of fast- and slow-relaxing populations of half-sarcomeres. Isometric muscle twitch simulations predicted a complex relationship between relaxation time and the proportion of fast-versus slow-relaxing cells in heterogeneous tissues. Specifically, a 50/50 mixture of fast and slow cells did not lead to relaxation time that was the mean of the relaxation times associated with the two pure cases. Rather, the mean relaxation time was achieved at a ratio of 70:30 slow:fast relaxing cells, suggesting a disproportionate impact of fast-relaxing cells on overall tissue relaxation. To examine whether this behavior persists in vitro, we constructed engineered heart tissues from two lines of fast- and slow-relaxing human iPSC-derived cardiomyocytes. Cell tracking via fluorescent nanocrystals confirmed the presence of both cell populations in the 50/50 mixed tissues at the time of mechanical characterization. Isometric muscle twitch relaxation times of these mixed-population engineered heart tissues showed agreement with the predictions from the model, namely that the measured relaxation rate of 50/50 mixed tissues more closely resembled that of tissues made with 100% fast-relaxing cells. Our observations suggest that cardiomyocyte diversity can play an important role in determining tissue-level relaxation.

Extracellular Matrix From Hypertrophic Myocardium Provokes Impaired Twitch Dynamics in Healthy Cardiomyocytes

•

The goal of this study was to examine the effects of diseased extracellular matrix on the behavior of healthy heart cells.

•

Myocardium was harvested from a genetically engineered miniature pig carrying the hypertrophic cardiomyopathy mutation MYH7 R403Q and from a wild-type littermate.

•

Engineered heart tissues were created by seeding healthy human induced pluripotent stem cell–derived cardiomyocytes onto thin strips of decellularized porcine myocardium.

•

Engineered heart tissues made from the extracellular matrix of hypertrophic cardiomyopathy hearts exhibit increased stiffness, impaired relaxation, and increased force development.

•

This suggests that diseased extracellular matrix can provoke abnormal contractile behavior in otherwise healthy cardiomyocytes.

Hypertrophic cardiomyopathy (HCM) is often caused by single sarcomeric gene mutations that affect muscle contraction. Pharmacological correction of mutation effects prevents but does not reverse disease in mouse models. Suspecting that diseased extracellular matrix is to blame, we obtained myocardium from a miniature swine model of HCM, decellularized thin slices of the tissue, and re-seeded them with healthy human induced pluripotent stem cell–derived cardiomyocytes. Compared with cardiomyocytes grown on healthy extracellular matrix, those grown on the diseased matrix exhibited prolonged contractions and poor relaxation. This outcome suggests that extracellular matrix abnormalities must be addressed in therapies targeting established HCM.

Fibrostenotic eosinophilic esophagitis might reflect epithelial lysyl oxidase induction by fibroblast-derived TNF-α

BACKGROUND

Fibrosis and stricture are major comorbidities in patients with eosinophilic esophagitis (EoE). Lysyl oxidase (LOX), a collagen cross-linking enzyme, has not been investigated in the context of EoE.

OBJECTIVE

We investigated regulation of epithelial LOX expression as a novel biomarker and functional effector of fibrostenotic disease conditions associated with EoE.

METHODS

LOX expression was analyzed by using RNA-sequencing, PCR assays, and immunostaining in patients with EoE; cytokine-stimulated esophageal 3-dimensional organoids; and fibroblast-epithelial cell coculture, the latter coupled with fluorescence-activated cell sorting.

RESULTS

Gene ontology and pathway analyses linked TNF-α and LOX expression in patients with EoE, which was validated in independent sets of patients with fibrostenotic conditions. TNF-α-mediated epithelial LOX upregulation was recapitulated in 3-dimensional organoids and coculture experiments. We find that fibroblast-derived TNF-α stimulates epithelial LOX expression through activation of nuclear factor κB and TGF-β-mediated signaling. In patients receiver operating characteristic analyses suggested that LOX upregulation indicates disease complications and fibrostenotic conditions in patients with EoE.

CONCLUSIONS

There is a novel positive feedback mechanism in epithelial LOX induction through fibroblast-derived TNF-α secretion. Esophageal epithelial LOX might have a role in the development of fibrosis with substantial translational implications.

Factors associated with 'caregiver burden' for atrial fibrillation patients

BACKGROUND

The burden on caregivers providing support to atrial fibrillation (AF) patients has not been evaluated.

OBJECTIVE

To examine the interrelationship between unpaid caregiver, patient and thromboprophylaxis characteristics and caregiver burden in AF.

METHODS

We conducted a cross-sectional survey study of AF patient-caregiver dyads recruited from cardiology clinics at an urban teaching hospital. Eligible patients had a diagnosis of AF, received thromboprophylaxis to prevent stroke, lived in the community and had an adult, unpaid, English-speaking caregiver. Hierarchical multivariate regression was used to evaluate the association between caregiver, patient and thromboprophylaxis characteristics and caregiver burden as measured by the 'Caregiver Reaction Assessment' (CRA).

RESULTS

Eighty patient-caregiver dyads were surveyed. The mean ± standard deviation scores for each CRA domain were 'Disrupted schedule' (2.4 ± 1.0), 'Financial problems' (2.1 ± 0.8), 'Lack of family support' (1.9 ± 0.7), 'Health problems' (1.9 ± 0.7) and 'Self-esteem' (0.9 ± 0.5). Significantly greater caregiver burden due to 'Disrupted schedule' was seen in those spending > 4 h/week providing care and when caring for frail, sick or disabled patients, with higher CHADS2 scores and requiring help with their medications. 'Financial problems' burden scores were significantly associated with caring for frail patients and those requiring more frequent office follow-up. 'Lack of family support' scores were inversely associated with having somebody else to help provide care and increased as patients CHADS2 score increased. Lower 'Health problem' burden scores were associated with female gender and higher scores with the need to spend > 4 h/week providing care.

CONCLUSION

The greatest burden to caregivers of AF patients occurs due to schedule disruption.

Effect of pharmacological therapies for stroke prevention on major gastrointestinal bleeding in patients with atrial fibrillation

Various antiplatelet and anticoagulation options are available for stroke prevention in patients with atrial fibrillation (AF). Currently, it is unclear whether these agents differ in their propensity to cause major gastrointestinal bleeding (MGIB). To our knowledge, no systematic evaluation of MGIB rates from randomised controlled trials (RCTs) of pharmacological stroke prevention in patients with AF has been conducted. Two independent investigators conducted systematic literature searches in MEDLINE and CENTRAL from the earliest possible date through November 2010. To be included, RCTs had to evaluate an adult population with AF or flutter and report data on the incidence of MGIB. Peto's odds ratios (ORs) with associated 95% confidence intervals (CIs) were calculated for all possible pair-wise comparisons of pharmacological stroke prevention alternatives. A total of 16 unique trials (n = 42,983) met inclusion criteria. The reported incidence of MGIB in placebo or control arms of identified trials was as high as 1.5%. Upon pair-wise meta-analysis of different pharmacological strategies, adjusted-dose vitamin K antagonists (VKAs) were found to be associated with a higher odds of MGIB compared with placebo/control (OR 3.21, 95% CI 1.32-7.82) and aspirin (or triflusal or indobufen) (OR 1.92, 95% CI 1.08-3.41). The addition of aspirin (or triflusal) to an adjusted-dose VKA resulted in greater odds of MGIB compared with aspirin alone (OR 4.72, 95% CI 1.35-16.49) and adjusted-dose VKA alone (OR 2.66, 95% CI 1.05-6.74). While aspirin increased the odds of MBIG by 3.23-fold compared with placebo/control, this finding did not reach statistical significance. The combination of aspirin and clopidogrel increased patients' odds of MGIB compared with aspirin alone (OR 1.93, 95% CI 1.46-2.56). Dabigatran was associated with a 30% increased odds of MGIB compared with adjusted-dose VKA (OR 1.30, 95% CI 1.06-1.59); however, ximelagatran was not. Low-intensity VKA therapy, alone or in combination with aspirin, was not associated with increased odds of MGIB compared with any (active-) comparator. The MGIB is a concern for patients with AF receiving pharmacological stroke prevention. Current RCT data suggest that dabigatran and adjusted-dose VKA therapy are associated with the highest odds of MGIB. Aspirin was not found to increase patients' odds of MGIB; however, this finding may be the result of type 2 error. Dual therapy resulting from the addition of an antiplatelet agent was typically associated with further increased odds of MGIB compared with monotherapy.

Are the risk factors listed in warfarin prescribing information associated with anticoagulation-related bleeding? A systematic literature review

Warfarin significantly reduces thromboembolic risk, but perceptions of associated bleeding risk limit its use. The evidence supporting the association between bleeding and individual patient risks factors is unclear. This systematic review aims to determine the strength of evidence supporting an accentuated bleeding risk when patients with risk factors listed in the warfarin prescribing information are prescribed the drug. A systematic literature search of MEDLINE and Cochrane CENTRAL was conducted to identify studies reporting multivariate relationships between prespecified covariates and the risk of bleeding in patients receiving warfarin. The prespecified covariates were identified based on patient characteristics for bleeding listed in the warfarin package insert. Each covariate was evaluated for its association with specific types of bleeding. The quality of individual evaluations was rated as 'good', 'fair' or 'poor' using methods consistent with those recommended by the Agency for Healthcare Research and Quality (AHRQ). Overall strength of evidence was determined using the Grading of Recommendations Assessment, Development (GRADE) criteria and categorised as 'insufficient', 'very low', 'low', 'moderate' or 'high'. Thirty-four studies, reporting 134 multivariate evaluations of the association between a covariate and bleeding risk were identified. The majority of evaluations had a low strength of evidence for the association between covariates and bleeding and none had a high strength of evidence. Malignancy and renal insufficiency were the only two covariates that had a moderate strength of evidence for their association with major and minor bleeding respectively. The associations between covariates listed in the warfarin prescribing information and increased bleeding risk are not well supported by the medical literature.

Lack of effect of statins on maintenance of normal sinus rhythm following electrical cardioversion of persistent atrial fibrillation

Randomised controlled trials evaluating the effect of statin use on maintenance of normal sinus rhythm (NSR) after electrical cardioversion (ECV) of persistent atrial fibrillation (AF) have demonstrated conflicting results. However, many of these trials were of relatively small size and thus underpowered to adequately evaluate this end-point. The aim of this study was to conduct a meta analysis evaluating the effect of statin use on maintenance of NSR after ECV of persistent AF. Randomised controlled trials evaluating the use of statins to maintain NSR after ECV of AF were identified through a systematic search including Medline (1950 through December 2009), the Cochrane CENTRAL Register (4th quarter, 2009) and a manual review of references without any language restrictions. Pooled estimates of effect are reported as relative risks (RRs) with accompanying 95% confidence intervals (CIs) using a random-effects model. Four trials (n = 424; range: 48-212) were identified and subject to meta analysis. Evaluated statins included atorvastatin 10 and 80 mg and pravastatin 40 mg/day. Over a mean of 2.1 months (range: 1-3 months) statins did not increase the likelihood of maintaining NSR following ECV (RR, 1.12; 95%CI, 0.85-1.46) compared with control. Current evidence does not suggest that statins are associated with an increased probability of maintaining NSR following ECV of persistent AF.

Understanding heterogeneity in meta-analysis: the role of meta-regression

BACKGROUND

Meta-regression has grown in popularity in recent years, paralleling the increasing numbers of systematic reviews and meta-analysis published in the biomedical literature. However, many clinicians and decision-makers may be unfamiliar with the underlying principles and assumptions made within meta-regression leading to incorrect interpretation of their results.

AIMS

This paper reviews the appropriate use and interpretation of meta-regression in the medical literature, including cautions and caveats to its use.

MATERIALS & METHODS

A literature search of MEDLINE (OVID) from 1966-February 2009 was conducted to identify literature relevant to the topic of heterogeneity and/or meta-regression in systematic reviews and meta-analysis.

RESULTS

Meta-analysis, a statistical method of pooling data from studies included in a systematic review, is often compromised by heterogeneity of its results. This could include clinical, methodological or statistical heterogeneity. Meta-regression, said to be a merging of meta-analytic and linear regression principles, is a more sophisticated tool for exploring heterogeneity. It aims to discern whether a linear relationship exists between an outcome measure and on or more covariates. The associations found in a meta-regression should be considered hypothesis generating and not regarded as proof of causality.

CONCLUSIONS

The current review will enable clinicians and healthcare decision-makers to appropriately interpret the results of meta-regression when used within the constructs of a systematic review, and be able to extend it to their clinical practice.

The impact of gender on survival amongst patients with implantable cardioverter defibrillators for primary prevention against sudden cardiac death

BACKGROUND

Implantable cardioverter defibrillators (ICDs) are a life-saving therapy for many patients with cardiovascular disease at increased risk of fatal dysrhythmias. As men comprise the majority of the study population (67-92%) in clinical trials, the benefit to women is unknown. We performed a meta-analysis of primary prevention trials to evaluate the impact of ICDs in men and women on death from any cause.

METHODS

Included trials met the following criteria: (i) randomized controlled trials versus standard of care, (ii) ICD used as primary prevention in a well-described protocol and (iii) data provided on risk of death from any cause for both male and female patients.

RESULTS

Five clinical trials were included in this meta-analysis. The risk of death from any cause was significantly reduced by 26% in male patients who received ICD therapy compared to control, hazard ratio (HR) 0.74 (95% CI 0.60-0.91) but not amongst female patients, HR 0.81 (95% CI 0.60-1.09). As the COMPANION trial evaluated the combination of biventricular pacemaker with ICD therapy we conducted a separate analysis without the inclusion of this study. Male patients receiving ICD therapy demonstrated a similar 24% reduction in risk of death from any cause, HR 0.76 (95% CI 0.58-0.99) whilst female patients demonstrated a reduction of only 12%, HR 0.88 (95% CI 0.63-1.22).

CONCLUSIONS

Unlike their male counterparts, females did not significantly benefit from ICD therapy and without concurrent biventricular pacing, appear only to achieve a nonsignificant 12% reduction in risk of death.

Changes in P-wave dispersion and P-wave duration after open heart surgery are associated with the peak incidence of atrial fibrillation

BACKGROUND

Increased P-wave dispersion (P-disp) and maximum P-wave duration (P-max) predict the development of atrial fibrillation (AF) in the general population. The present study evaluates the time-dependent relationship of P-disp and P-max after open heart surgery.

METHODS AND RESULTS

P-disp and P-max were measured in the perioperative period of open heart surgery (one day before surgery through postoperative day 4). Compared with the baseline, P-max decreased immediately after open heart surgery (112.63 +/- 7.4 ms vs 106.9 +/- 8.2 ms, P =.005). An increase in P-disp was observed between postoperative days 1 and 2 (37.5 +/- 6.8 ms vs 43.1 +/- 4.5 ms, P <.05), and postoperative days 1 and 3 (37.5 +/- 6.8 ms vs 44.1 +/- 6.6 ms, P <.05). There was also an increase in the P-max between postoperative day 1 and 3 (103 +/- 8.3 ms vs 110 +/- 7.7 ms, P <.05).

CONCLUSIONS

Nonuniform atrial conduction (P-disp) is greatest on days 2 and 3 after open heart surgery, and the longest atrial conduction time (P-max) is greatest on day 3 after open heart surgery, findings that coincide with the time of greatest risk for AF. (Heart Lung((R)) 2001;30:466-71.)

A comparison of the QT and QTc dispersion among patients with sustained ventricular tachyarrhythmias and different etiologies of heart disease

OBJECTIVES

To determine if etiology of heart disease is associated with differences in QT and QTc dispersion among patients with ventricular tachyarrhythmias.

METHODS

This study was undertaken in 145 patients undergoing electrophysiological testing for sustained ventricular tachycardia or ventricular fibrillation. Patients were divided into groups based on etiology of heart disease determined by history, ECG, coronary angiography, and echocardiography. The groups included patients with: dilated cardiomyopathy (n = 29), myocardial infarction (n = 90), established coronary artery disease without a myocardial infarction (n = 11), or hypertension induced left ventricular hypertrophy (n = 15). The QT intervals on a 12--lead ECG were determined and Bazett's formula was used to derive the QTc intervals. The QT and QTc dispersion were determined by subtracting the shortest QT(c) interval from the longest on each 12-lead recording.

RESULTS

The patients with dilated cardiomyopathy had significantly higher QT and QTc dispersion values as compared to any of the other three groups (P < 0.05 for both). No other differences in electrocardiographic variables were found between groups.

CONCLUSIONS

In a group of patients with a history of ventricular tachycardia or ventricular fibrillation, QT and QTc dispersion are significantly greater among patients with dilated cardiomyopathy than for patients with a previous myocardial infarction, established coronary artery disease without a myocardial infarction, or hypertensive left ventricular hypertrophy.

Amiodarone in the new AHA guidelines for ventricular tachyarrhythmias

OBJECTIVE

To delineate amiodarone's role in the new American Heart Association guidelines for ventricular tachyarrhythmias, review the literature that supports the use of amiodarone in ventricular tachyarrhythmias, describe the pharmaceutical properties of amiodarone and elucidate their clinical implications, and discuss the dosing, preparation, and administration of amiodarone.

DATA SOURCES

A search of MEDLINE (1966-October 2000) database and EMBASE Drugs and Pharmacology database (1980-October 2000) was performed. References from published articles and tertiary references were used to gather additional data.

DATA EXTRACTION

All articles were screened, and pertinent studies were identified and evaluated.

DATA SYNTHESIS

Recent trials have demonstrated amiodarone's usefulness in the setting of ventricular tachyarrhythmias. Based on these investigations and contrary to past guidelines, amiodarone is included in the 2000 advanced cardiovascular life support guidelines as a possible agent for hemodynamically stable monomorphic ventricular tachycardia (VT), non-QT prolonged polymorphic VT, and ventricular fibrillation (VF)/pulseless VT. Although not specifically evaluated in the setting of hemodynamically stable monomorphic VT and non-QT prolonged polymorphic VT, investigations by the intravenous Amiodarone Multicenter Trial Group and other clinical trials make amiodarone an acceptable choice for these arrythmia categories. The results of the ARREST (Resuscitation of Refractory Sustained Ventricular Tachyarrhythmias) trial prove amiodarone to be the antiarrhythmic of choice for VF/pulseless VT.

CONCLUSIONS

Amiodarone is classified as a IIb therapeutic intervention for all three arrhythmia categories, which makes it an acceptable, safe, and useful agent with fair to good evidence to support its use. In addition, amiodarone requires careful preparation and delivery to achieve safe and effective outcomes.

Hematologic and chemical changes observed during and after cardiac arrest in a canine model--a pilot study

STUDY OBJECTIVE

To evaluate the effect of cardiac arrest and cardiopulmonary resuscitation (CPR) on blood chemistry in a canine model.

DESIGN

Evaluative canine animal study.

SETTING

Animal laboratory accredited by the Association for Assessment and Accreditation of Laboratory Animals.

SUBJECTS

Twenty-six adult mongrel dogs.

INTERVENTION

The dogs underwent an episode of induced fibrillatory cardiac arrest for 3 minutes followed by 10 minutes of standard CPR. Blood samples were taken at baseline (before cardiac arrest), after 10 minutes of ventricular fibrillation, and 10 minutes after successful resuscitation for determination of blood chemistries and hematologic parameters.

MEASUREMENTS AND MAIN RESULTS

Glucose, blood urea nitrogen, serum creatinine, sodium, potassium, chloride, calcium, phosphorus, uric acid, alkaline phosphatase, lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, protein, albumin, cholesterol, triglycerides, iron, white blood cell count, red blood cell count, and hematocrit were measured. Significant changes (p<0.05) in values obtained during CPR versus baseline values were noted for all laboratory parameters except blood urea nitrogen, chloride, and alkaline phosphatase. Eighteen dogs achieved return of spontaneous circulation (ROSC); their laboratory values were obtained after CPR. Significant changes (p<0.05) after ROSC compared with baseline were noted for all laboratory values except chloride, blood urea nitrogen, uric acid, alkaline phosphatase, glucose, potassium, calcium, triglycerides, iron, red blood cell count, and hematocrit.

CONCLUSION

Results indicate that significant changes in blood chemistries and hematologic parameters occur during and after CPR. Clinicians should note these normal laboratory parameter changes when interpreting laboratory data in patients who experience cardiac arrest.

An evaluation of the change in electrocardiographic P-wave variables after acute caffeine ingestion in normal volunteers

BACKGROUND

Caffeine's effect on supraventricular dysrhythmias is poorly understood, and establishing a marker to predict atrial fibrillation may help to explain supraventricular dysrhythmias caused by caffeine.

OBJECTIVE

To evaluate the effects of caffeine (mean 6.1 mg/kg) on maximum P-wave duration and P-wave dispersion in normal volunteers.

METHOD

A randomised, double-blind, placebo-controlled, crossover study in 10 healthy volunteers at least 17 years of age at the University of Connecticut. Participants abstained from caffeinated products for at least 2 days before study initiation and were randomly allocated on different days to receive placebo or caffeine 400 mg. For each of the study phases, a baseline 12-lead electrocardiogram (ECG) was performed and a subsequent 12-lead ECG was performed 3 h after ingesting the study drug.

RESULTS

No significant changes were found within intra- or intergroup comparisons for any P-wave variables measured.

CONCLUSION

Single dose caffeine (400 mg) does not affect average P-wave duration, maximum P-wave duration or P-wave dispersion in normal individuals.

Evaluation of electrocardiographic and hemodynamic effects of caffeine with acute dosing in healthy volunteers

STUDY OBJECTIVE

To evaluate the effects of moderate, single-dose caffeine consumption on electrocardiographic variables: PR, QRS, QT, QTc, and RR intervals, and QT and QTc interval dispersion. Effects of caffeine on blood pressure and heart rate also were evaluated.

DESIGN

Randomized, double-blind, placebo-controlled, crossover study.

SETTING

University school of pharmacy.

PATIENTS

Ten healthy volunteers aged 17 years or older.

INTERVENTION

Participants abstained from caffeinated products for at least 2 days before the study began and were randomly designated to receive placebo or caffeine 400 mg on various days. For each of the study phases, a baseline 12-lead electrocardiogram (ECG) was performed and a subsequent 12-lead ECG performed 3 hours after ingesting the study drug. Blood pressure readings were taken with each ECG.

MEASUREMENTS AND MAIN RESULTS

No significant changes in any intragroup or intergroup electrocardiographic variables occurred. Caffeine increased blood pressure (systolic blood pressure [SBP]/diastolic blood pressure [DBP]) from 118+/-5/75+/-6 mm Hg to 128+/-8/77+/-7 mm Hg versus baseline (p=0.0022 and p=0.0368 for SBP and DBP, respectively). After drug dosing, SBP in the caffeine group was significantly higher than in the placebo group (128+/-8 mm Hg versus 119+/-7 mm Hg, p=0.0174).

CONCLUSION

Moderate caffeine consumption by healthy young adults does not acutely affect PR, QRS, QT, QTc, and RR intervals, or QT and QTc interval dispersion. Caffeine-naive subjects experienced persistent elevations in SBP and DBP 3 hours after caffeine ingestion, indicating that longer caffeine abstinence than that which is recommended is necessary for blood pressure determination in the clinical setting.

Oral amiodarone for prevention of atrial fibrillation after open heart surgery, the Atrial Fibrillation Suppression Trial (AFIST): a randomised placebo-controlled trial

BACKGROUND

Beta-blockers and amiodarone reduce the frequency of atrial fibrillation after open-heart surgery but the effectiveness of oral amiodarone in older patients already receiving beta-blockers is unknown. We have assessed the efficacy of oral amiodarone in preventing atrial fibrillation in patients aged 60 years or older undergoing open-heart surgery.

METHODS

We did a randomised, double-blind placebo-controlled trial in which patients undergoing open-heart surgery (n=220, average age 73 years) received amiodarone (n=120) or placebo (n=100). Patients enrolled less than 5 days before surgery received 6 g of amiodarone or placebo over 6 days beginning on preoperative day 1. Patients enrolled at least 5 days before surgery received 7 g over 10 days beginning on preoperative day 5.

FINDINGS

Patients on amiodarone had a lower frequency of any atrial fibrillation (22.5% vs 38.0%; p=0.01; absolute difference 15.5% [95% CI 3.4-27.6%]), and there were significant differences in favour of the active drug for symptomatic atrial fibrillation (4.2% vs 18.0%, p=0.001), cerebrovascular accident (1.7% vs 7.0%, p=0.04), and postoperative ventricular tachycardia (1.7% vs 7.0%, p=0.04). Beta-blocker use (87.5% amiodarone vs 91.0% placebo), nausea (26.7% vs 16.0%), 30-day mortality (3.3% vs 4.0%), symptomatic bradycardia (7.5% vs 7.0%), and hypotension (14.2% vs 10.0%) were similar.

INTERPRETATION

Oral amiodarone prophylaxis in combination with beta-blockers prevents atrial fibrillation and symptomatic fibrillation and reduces the risk of cerebrovascular accidents and ventricular tachycardia.

A placebo controlled evaluation of the antifibrillatory effects of carvedilol

This article evaluates the antifibrillatory effects of carvedilol 5 mg/kg and vehicle (dimethyl-formamide) over time. Sprague-Dawley rats were anesthetized and intubated. They underwent baseline ventricular fibrillation threshold (VFT) determination and then received 1 of the 2 treatments (n = 10/group) over 8 minutes. VFT and determinations were performed at 2, 7, 15, 30, 45, and 60 minutes postinfusion. Carvedilol significantly increased the VFT at 2, 7, 15, 30 minutes versus baseline and the vehicle control group. Carvedilol significantly reduced the heart rate and the mean arterial pressure at every evaluable time point versus baseline and vehicle control. Carvedilol showed significant antifibrillatory effects versus baseline and vehicle for the first 30 minutes but not thereafter, even though the heart rate and mean arterial pressure remain significantly reduced.

Efficacy and cost analysis of ibutilide

OBJECTIVE

To determine the efficacy and safety of ibutilide in atrial fibrillation (AF) and atrial flutter (AFl) in a clinical setting and to compare the cost of first-line ibutilide with that of projected first-line electrical cardioversion (EC) from a hospital and third-party payer perspective.

METHODS

Medical records of all patients (n = 60) who received ibutilide from August 1996 to March 1998 were reviewed. Efficacy was defined as successful conversion to sinus rhythm within 60 minutes of the end of the infusion, and the maintenance of sinus rhythm until hospital discharge. Safety was evaluated by determining the incidence of torsade de pointes. Charges for EC and drug administration were obtained from the hospital database and converted to costs using cost/charge ratios. Hospital costs included drug, drug administration, cardiac intensive care laboratory fee, and the cost of managing torsade de pointes. The third-party payer calculation included all of the above plus the cardiologist and anesthesiologist fees.

RESULTS

Fifty percent of patients with AF or AFl were successfully converted with ibutilide; 67% of these remained in sinus rhythm at hospital discharge. Three patients experienced nonsustained torsade de pointes; all resolved with pharmacologic management. From a hospital perspective, the cost of first-line ibutilide was greater than the cost of first-line EC ($280 vs. $138 per patient). However, from a third-party payer perspective, the use of ibutilide saved approximately $324 per patient ($718 vs. $1042).

CONCLUSIONS

The efficacy and safety of ibutilide in the clinical setting are consistent with data reported in clinical trials. In contrast to a previous decision analysis, ibutilide was not associated with cost savings from a hospital perspective, but was from a payer perspective.

Assessment of the drug interaction between alteplase and nitroglycerin: an in vitro study

Alteplase is the most commonly administered thrombolytic agent in the United States. However, concurrent therapy with nitroglycerin reduces plasma alteplase concentrations and its clinical efficacy. We sought to determine if this interaction is concentration and pH dependent. Seventy plasma samples were prepared and divided into three groups: alteplase 500 IU/ml alone (group 1), alteplase 500 IU/ml plus nitroglycerin 5 ng/ml (group 2), and alteplase 500 IU/ml plus nitroglycerin 200 ng/ml (group 3). The samples were analyzed at time zero and 3 hours (incubated at 37 degrees C). Group 1 had significantly higher plasma alteplase concentrations than group 3 (p<0.001). When alteplase and nitroglycerin are combined, the degradation of alteplase in plasma is enhanced.