Jeremy S. Paikin

Creatine Monohydrate and Conjugated Linoleic Acid Improve Strength and Body Composition Following Resistance Exercise in Older Adults

Aging is associated with lower muscle mass and an increase in body fat. We examined whether creatine monohydrate (CrM) and conjugated linoleic acid (CLA) could enhance strength gains and improve body composition (i.e., increase fat-free mass (FFM); decrease body fat) following resistance exercise training in older adults (>65 y). Men (N = 19) and women (N = 20) completed six months of resistance exercise training with CrM (5g/d)+CLA (6g/d) or placebo with randomized, double blind, allocation. Outcomes included: strength and muscular endurance, functional tasks, body composition (DEXA scan), blood tests (lipids, liver function, CK, glucose, systemic inflammation markers (IL-6, C-reactive protein)), urinary markers of compliance (creatine/creatinine), oxidative stress (8-OH-2dG, 8-isoP) and bone resorption (Ν-telopeptides). Exercise training improved all measurements of functional capacity (P<0.05) and strength (P<0.001), with greater improvement for the CrM+CLA group in most measurements of muscular endurance, isokinetic knee extension strength, FFM, and lower fat mass (P<0.05). Plasma creatinine (P<0.05), but not creatinine clearance, increased for CrM+CLA, with no changes in serum CK activity or liver function tests. Together, this data confirms that supervised resistance exercise training is safe and effective for increasing strength in older adults and that a combination of CrM and CLA can enhance some of the beneficial effects of training over a six-month period. Trial Registration. ClinicalTrials.gov NCT00473902

Triple Antithrombotic Therapy in Patients With Atrial Fibrillation and Coronary Artery Stents

Case presentation: A 76-year-old man with rate-controlled atrial fibrillation (AF), diabetes mellitus, and prior stroke who is receiving warfarin to prevent recurrent stroke presents to the emergency department with chest pain, elevated serum troponin, and an ECG that demonstrates ST depression in the precordial leads. Cardiac catheterization reveals an ulcerated plaque and partially obstructive thrombus in the left circumflex coronary artery. Percutaneous coronary intervention is performed with placement of 2 bare-metal stents. What is the optimal antithrombotic therapy? What is the optimal antithrombotic therapy if the patient receives drug-eluting stents instead of bare-metal stents? Meta-analyses of randomized controlled trials in patients with nonvalvular AF indicate that oral vitamin K antagonist (VKA) therapy reduces the risk of stroke or systemic embolism by 64% compared with placebo and by 39% compared with aspirin.1,2 In the ACTIVE trials (Atrial fibrillation Clopidogrel Trial with Irbesartan for prevention of Vascular Events), warfarin reduced the risk of stroke or systemic embolism by 42% compared with dual-antiplatelet therapy with the combination of aspirin and clopidogrel,3 whereas dual-antiplatelet therapy reduced the risk by 28% compared with aspirin alone.4 Recently, the RE-LY trial (Randomized Evaluation of Long-term anticoagulant therapY) showed that compared with warfarin the oral direct thrombin inhibitor, dabigatran etexilate given at a dose of 150 mg twice daily reduces stroke with less intracranial bleeding, and dabigatran 110 mg twice daily has similar efficacy with less bleeding.5 Dabigatran etexilate is not yet approved for stroke prevention in AF. The 2006 American College of Cardiology/American Heart Association/European Society of Cardiology and the 2008 American College of Chest Physicians guidelines both recommend stratification of patients with AF according to their risk of stroke to guide the choice of antithrombotic therapy. The guidelines recommend VKA therapy for patients with a CHADS2 score >1, either aspirin or …

New antithrombotic agents--insights from clinical trials.

Antithrombotic agents are the cornerstones of therapy for thrombosis. The compositions of arterial and venous clots differ, rendering antiplatelet agents more effective for arterial thrombosis and anticoagulants more effective for venous disease. Despite taking acetylsalicylic acid, some patients with arterial disease experience thrombotic events. The addition of the ADP-receptor antagonist clopidogrel to therapeutic regimens containing acetylsalicylic acid improves outcomes in patients with acute coronary syndromes and in those undergoing percutaneous coronary intervention. However, clopidogrel has several limitations, including variable absorption, drug–drug interactions and genetic factors that lead to reduced generation of the active metabolite, and a delayed onset and offset of action. A search for new ADP-receptor inhibitors has yielded drugs such as prasugrel, ticagrelor, and cangrelor. For patients with venous thrombosis, the coumarins have been the only available oral anticoagulants for more than 60 years. Despite their effectiveness in preventing and treating thromboembolism, coumarins have well-documented limitations, including drug–drug and drug–dietary interactions, a narrow therapeutic range, and inconvenience and cost of monitoring therapy. A search for new oral anticoagulants has yielded drugs such as dabigatran etexilate, rivaroxaban, and apixaban. In this article, we review these new antithrombotic agents and provide plausible explanations for the results of phase III randomized controlled trials of these drugs.

New oral anticoagulants for stroke prevention in atrial fibrillation: impact of study design, double counting and unexpected findings on interpretation of study results and conclusions

Four recently introduced new oral anticoagulants (dabigatran, rivaroxaban, apixaban and edoxaban) have been shown to be at least as efficacious and safe as warfarin for stroke prevention in patients with atrial fibrillation in their respective trials. The first three have been approved, while edoxaban is awaiting regulatory approval. Several guidelines have endorsed the approved new oral anticoagulants over warfarin because of their favourable risk-benefit ratio, low propensity for food and drug interactions, and lack of requirement for routine coagulation monitoring. In this invited review, we summarise the results of the four studies and discuss widely held conclusions. We take a step further and discuss how differences in study design, analysis plan, and unexpected events affect the interpretation of the study results. Finally, we take our re-interpretation of study results and discuss how they might impact clinical practice and anticoagulant choice for patients.

Effectiveness and safety of combined antiplatelet and anticoagulant therapy: A critical review of the evidence from randomized controlled trials

Antiplatelet and anticoagulant drugs are effective for the prevention of arterial and venous thrombosis but patients continue to experience major cardiovascular events despite their use. Strategies to improve the effectiveness of antithrombotic therapies include selecting the optimal drug and dosing regimen, the use of combinations of antiplatelet and anticoagulant drugs and the development of new more effective drugs to replace existing therapies. Evidence from randomized controlled trials indicates that the combination of aspirin and an anticoagulant is more effective than aspirin alone for the prevention of recurrent cardiovascular events in patients with acute coronary syndrome and is more effective than anticoagulation alone for the prevention of thromboembolic events in patients with mechanical heart valves, but at a cost of increased bleeding. Randomized controlled trials provide no evidence for improved effectiveness of combination therapy compared with antiplatelet therapy alone for the prevention of recurrent cardiovascular events in patients with non-cardioembolic stroke or peripheral artery disease, or compared with anticoagulant therapy alone for the prevention of stroke in patients with atrial fibrillation. Despite lack of evaluation in randomized controlled trials, combination therapy is commonly used in patients with separate indications for antiplatelet therapy (e.g., acute coronary syndrome, recent coronary artery stent) and anticoagulant therapy (e.g., atrial fibrillation with at least one additional risk factor for stroke). Randomized trials are urgently required to evaluate the effectiveness and safety of combining antiplatelet and anticoagulant therapy in these settings.

Multiple daily doses of acetyl‐salicylic acid (ASA) overcome reduced platelet response to once‐daily ASA after coronary artery bypass graft surgery: a pilot randomized controlled trial

The efficacy of ASA for prevention of graft failure following CABG surgery may be limited by incomplete platelet inhibition due to increased post‐operative platelet turnover.

Timing the First Postoperative Dose of Anticoagulants: Lessons Learned From Clinical Trials

The non-vitamin K antagonist oral anticoagulants (NOACs), rivaroxaban, apixaban, and dabigatran, have been shown in phase 3 trials to be effective for thromboprophylaxis in patients undergoing elective hip or knee arthroplasty. Results from prior studies suggested that the safety of anticoagulants in such patients was improved if the first postoperative dose was delayed for at least 6 h after surgery. The timing of the first postoperative dose of the NOACs tested in phase 2 studies differed among the three NOACs: dabigatran was started 1 to 4 h postoperatively, whereas rivaroxaban and apixaban were started at least 6 and 12 h, postoperatively, respectively. Our review of the timing of initiation of thromboprophylaxis in randomized trials provides three related lessons. First, clinical trials performed before the NOACs were evaluated demonstrated that delaying the first dose of prophylactic anticoagulation until after major surgery is effective and safe. Second, the optimal timing of the first dose of prophylactic anticoagulation after surgery depends on the dose that is selected. Third, the results of the phase 3 trials with NOACs for thromboprophylaxis support the concept that acceptable efficacy and safety can be achieved when the appropriate first postoperative dose of anticoagulant is delayed for at least 6 h after surgery.

Aspirin response variability after major orthopedic surgery

INTRODUCTION Variability in platelet response to aspirin has been reported in patients undergoing cardiac surgery but has rarely been described in other operative settings and its mechanism remains uncertain. We performed a prospective cohort study to investigate the variability in platelet response to aspirin and to explore its mechanism in patients undergoing major orthopedic surgery. MATERIALS AND METHODS Twelve aspirin-treated patients undergoing elective hip or knee replacement were recruited. Once-daily aspirin was continued throughout the perioperative period. We measured platelet function using light transmission aggregation (LTA) in response to arachidonic acid (PL(AA)) and serum thromboxane B(2) (TXB(2)) at baseline (before surgery) as well as on days 1, 2, 3, 4, 5, 6, and 8 after surgery. We defined aspirin low response as a PL(AA)>20%. RESULTS Six patients exhibited aspirin low response, which typically started on post-operative days 3 or 4; the remaining 6 patients had normal response to aspirin. Compared to aspirin responders, patients with aspirin low response showed significantly higher serum TXB(2) levels, a more pronounced early decrease in platelet count, and a significantly more rapid recovery of the platelet count after surgery. CONCLUSION Aspirin response variability occurred in patients after major orthopedic surgery, with one-half of the patients in our study exhibiting post-operative aspirin low response. Increased platelet turnover might be a contributor to aspirin response variability after orthopedic surgery.

Once versus twice daily aspirin after coronary bypass surgery: a randomized trial

Essentials Coronary artery bypass graft (CABG) failure is associated with myocardial infarction and death. We tested whether more frequent dosing improves aspirin (ASA) response following CABG surgery. Twice‐daily compared with once‐daily dosing reduces ASA hyporesponsiveness after CABG surgery. The efficacy of twice‐daily ASA needs to be tested in a trial powered for clinical outcomes.

Rofecoxib does not appear to increase the risk of venous thromboembolism: A systematic review of the literature

BACKGROUND AND OBJECTIVE Rofecoxib, a selective cyclo-oxygenase-2 (COX-2) inhibitor, has been associated with increased arterial thrombosis. It is unknown whether (COX-2) inhibition is associated with venous thromboembolism (VTE).We investigated, using a systematic review of the literature, the association between rofecoxib and venous thrombosis. METHODS A search strategy was developed and implemented to identify all English language studies in which rofecoxib was compared with placebo, irrespective of the primary outcome of the study. Study methodology and results were reviewed in a standardized manner using RefMan software. Confidence intervals and risk difference were calculated using a Poisson distribution. RESULTS The search strategy identified 1339 papers; 15 studies met our pre-specified inclusion criteria. The majority of trials were short in duration (~12 weeks). All studies met at least two of the three quality criteria. In 15,160 (9217 person years follow up) patients allocated to rofecoxib there were 8 VTEs reported, compared with 9 VTEs in 13147 (9092 person years) patients allocated to placebo (relative risk 0.87, 95% CI 0.29-2.56, p=NS). The estimated incidence of VTE was 86.8 per 100,000 (95% CI 37.5 -171.2) person years with rofecoxib, and 99.1 per 100,000 person years with placebo (95%CI 45.3 - 188). This difference is not statistically significant (p=0.78). CONCLUSIONS Our findings are limited by the relatively small number of events, although, the contributing sample size of 28307 subjects (18309 person years) is reasonable. From our best available data outlined in this manuscript, there is no increase in the risk of VTE with rofecoxib use.