Kenneth Gin

Self-monitoring of oral anticoagulation: systematic review and meta-analysis of individual patient data

BACKGROUND Uptake of self-testing and self-management of oral anticoagulation [corrected] has remained inconsistent, despite good evidence of their effectiveness. To clarify the value of self-monitoring of oral anticoagulation, we did a meta-analysis of individual patient data addressing several important gaps in the evidence, including an estimate of the effect on time to death, first major haemorrhage, and thromboembolism. METHODS We searched Ovid versions of Embase (1980-2009) and Medline (1966-2009), limiting searches to randomised trials with a maximally sensitive strategy. We approached all authors of included trials and requested individual patient data: primary outcomes were time to death, first major haemorrhage, and first thromboembolic event. We did prespecified subgroup analyses according to age, type of control-group care (anticoagulation-clinic care vs primary care), self-testing alone versus self-management, and sex. We analysed patients with mechanical heart valves or atrial fibrillation separately. We used a random-effect model method to calculate pooled hazard ratios and did tests for interaction and heterogeneity, and calculated a time-specific number needed to treat. FINDINGS Of 1357 abstracts, we included 11 trials with data for 6417 participants and 12,800 person-years of follow-up. We reported a significant reduction in thromboembolic events in the self-monitoring group (hazard ratio 0·51; 95% CI 0·31-0·85) but not for major haemorrhagic events (0·88, 0·74-1·06) or death (0·82, 0·62-1·09). Participants younger than 55 years showed a striking reduction in thrombotic events (hazard ratio 0·33, 95% CI 0·17-0·66), as did participants with mechanical heart valve (0·52, 0·35-0·77). Analysis of major outcomes in the very elderly (age ≥85 years, n=99) showed no significant adverse effects of the intervention for all outcomes. INTERPRETATION Our analysis showed that self-monitoring and self-management of oral coagulation is a safe option for suitable patients of all ages. Patients should also be offered the option to self-manage their disease with suitable health-care support as back-up. FUNDING UK National Institute for Health Research (NIHR) Technology Assessment Programme, UK NIHR National School for Primary Care Research.

Diagnostic accuracy of echocardiography for pulmonary hypertension: a systematic review and meta-analysis

Context Right heart catheterisation is the gold standard for the diagnosis of pulmonary hypertension. However, echocardiography is frequently used to screen for this disease and monitor progression over time because it is non-invasive, widely available and relatively inexpensive. Objective To perform a systematic review and quantitative meta-analysis to determine the correlation of pulmonary pressures obtained by echocardiography versus right heart catheterisation and to determine the diagnostic accuracy of echocardiography for pulmonary hypertension. Data sources MEDLINE, EMBASE, PapersFirst, the Cochrane collaboration and the Cochrane Register of controlled trials were searched and were inclusive as of February 2010. Study selection Studies were only included if a correlation coefficient or the absolute number of true-positive, false-negative, true-negative and false-positive observations was available, and the ‘reference standards’ were described clearly. Data extraction Two reviewers independently extracted the data from each study. Quality was assessed with the quality assessment for diagnostic accuracy studies. A random effects model was used to obtain a summary correlation coefficient and the bivariate model for diagnostic metaanalysis was used to obtain summary sensitivity and specificity values. Results 29 studies were included in the meta-analysis. The summary correlation coefficient between systolic pulmonary arterial pressure estimated from echocardiography versus measured by right heart catheterisation was 0.70 (95% CI 0.67 to 0.73; n=27). The summary sensitivity and specificity for echocardiography for diagnosing pulmonary hypertension was 83% (95% CI 73 to 90) and 72% (95% CI 53 to 85; n=12), respectively. The summary diagnostic OR was 13 (95% CI 5 to 31). Conclusions Echocardiography is a useful and noninvasive modality for initial measurement of pulmonary pressures but due to limitations, right heart catheterisation should be used for diagnosing and monitoring pulmonary hypertension.

Femoral vein delivery of contrast medium enhances transthoracic echocardiographic detection of patent foramen ovale

OBJECTIVES We postulated that femoral vein delivery of contrast medium because of streaming, might enhance precordial echocardiographic detection of patent foramen ovale. BACKGROUND Although precordial contrast echocardiography is widely used to diagnose patent foramen ovale, this method is limited by poor sensitivity. Previous investigators have demonstrated enhanced detection of atrial defects by the dye-dilution technique after delivery of contrast medium into the inferior rather than the superior vena cava. METHODS Transthoracic contrast examinations were performed in a randomly selected group of 70 patients (without previous history of cerebral or systemic embolus) undergoing cardiac catheterization. Paired contrast agent injections (10 ml dextrose in water/0.25 ml air) were administered from an upper extremity vein and femoral vein in each patient during spontaneous respiration, cough and Valsalva maneuvers. Studies were interpreted by an experienced echocardiographer unaware of the sequence and site of injections. Positive studies were semiquantitatively graded from +1 (minimal left ventricular opacification) to +4 (intense left ventricular opacification). Catheterization and echocardiographic assessment of patent foramen ovale were compared in 21 subjects. RESULTS Patent foramen ovale was detected significantly more often during femoral vein versus upper extremity contrast delivery (23 of 70 patients [prevalence 33%] vs. 9 of 70 patients [prevalence 13%], p < 0.001). The intensity of left ventricular opacification was also greater during femoral vein contrast injection. Precordial echocardiography combined with femoral contrast delivery was significantly more sensitive than cardiac catheterization for assessment of patent foramen ovale (8 of 21 patients vs. 2 of 21 patients, p < 0.05). CONCLUSIONS Femoral vein contrast delivery significantly enhances the ability of precordial contrast echocardiography to diagnose patent foramen ovale. Physiologic patency of the foramen ovale is more common (prevalence 33%) than previously documented.

Cost-effectiveness of self-managed versus physician-managed oral anticoagulation therapy

Background: Patient self-management of long-term oral anticoagulation therapy is an effective strategy in a number of clinical situations, but it is currently not a funded option in the Canadian health care system. We sought to compare the incremental cost and health benefits of self-management with those of physician management from the perspective of the Canadian health care payer over a 5-year period. Methods: We developed a Bayesian Markov model comparing the costs and quality-adjusted life years (QALYs) accrued to patients receiving oral anticoagulation therapy through self-management or physician management for atrial fibrillation or for a mechanical heart valve. Five health states were defined: no events, minor hemorrhagic events, major hemorrhagic events, thrombotic events and death. Data from published literature were used for transition probabilities. Canadian 2003 costs were used, and utility estimates were obtained from various published sources. Results: Self-management resulted in 3.50 fewer thrombotic events, 0.78 fewer major hemorrhagic events and 0.12 fewer deaths per 100 patients than physician management. The average discounted incremental cost of self-management over physician management was found to be

Prophylactic Intravenous Magnesium Sulphate in Addition to Oral β-Blockade Does Not Prevent Atrial Arrhythmias After Coronary Artery or Valvular Heart Surgery

989 (95% confidence interval [CI]

Aminophylline in bradyasystolic cardiac arrest: a randomised placebo-controlled trial

310–

Clinical Impact of Point-of-Care vs Laboratory Measurement of Anticoagulation

1655) per patient and the incremental QALYs gained was 0.07 (95% CI 0.06–0.08). The cost-effectiveness of self-management was

Changes in Left Atrial Appendage Dimensions Following Volume Loading During Percutaneous Left Atrial Appendage Closure

14 129 per QALY gained. There was a 95% chance that self-management would be cost-effective at a willingness to pay of

Outpatient Self-Management of Warfarin Therapy: A Pilot Study

23 800 per QALY. Results were robust in probabilistic and deterministic sensitivity analyses. Interpretation: This model suggests that self-management is a cost-effective strategy for those receiving long-term oral anticoagulation therapy for atrial fibrillation or for a mechanical heart valve.

Development and validation of a prediction rule for early discharge of low-risk emergency department patients with potential ischemic chest pain.

Background— Atrial arrhythmias (AA) are an important cause of morbidity after cardiac surgery. Efforts at prevention of postoperative AA have been suboptimal. Perioperative beta-blocker administration is the standard of care at many centers. Although prophylactic administration of magnesium sulfate (MgSO4) has been recommended, review of all previously published trials of MgSO4 reveals conflicting results. This study was designed to address methodological shortcomings from previous studies and is the largest randomized, placebo-controlled trial of intravenous (IV) MgSO4 for the prevention of AA after coronary artery bypass grafting or cardiac valvular surgery. Methods and Results— A total of 927 nonemergent cardiac surgery patients were stratified into 2 groups: isolated coronary artery bypass grafting (n=694), or valve surgery with or without coronary artery bypass grafting (n=233), and randomized to receive either 5g IV MgSO4 or placebo on removal of the cross-clamp, followed by daily 4-hour infusions, from postoperative day 1 until postoperative day 4. All patients were treated according to an established oral &bgr;-blocker protocol. Postoperative serum Mg levels were checked and standard of care was to administer IV MgSO4 for low serum levels. The primary end point was AA lasting ≥30 minutes or requiring treatment for hemodynamic compromise. There were no differences in the incidence of AA between patients who received IV MgSO4 or placebo (26.4% versus 24.3%, respectively). The results were similar when broken down according to stratified groups. Conclusions— In patients treated with a protocol for postoperative oral &bgr;-blocker after nonemergent cardiac surgery, the addition of prophylactic IV MgSO4 did not reduce the incidence of AA.