Support Group for Mechanical & Artificial Heart Valve Surgery & Using Warfarin
Saw this today and thought I would share.. its a paper from Canada last month re medical symposium paper on the effectiveness of warfarin.. Interesting re MHV patients..
Full report here: http://www.medscape.com/viewarticle/812885
"Warfarin is dead like the parrot in the Monty Python sketch and obsolete like cumbersome early mobile phones, Dorian told the audience. "I think we all agree that warfarin is hard to use and take . . . often causes bleeding, [has an impractical antidote], and as a consequence . . . its optimal benefits are . . . not realized," he said.
"I don't have to belabor the fact that [keeping the INR therapeutic range] is hard to do and is often not achieved," Dorian observed. In fact, probably two-thirds of patients in community practice who are receiving warfarin have imperfect INR control.
Once the INR is above 3, the risks of hemorrhage and thrombosis rise, he noted. As a result, warfarin is the second-most common drug-related complication—after hypoglycemia—that leads to a visit to an emergency room.
"For our elderly patients who are . . . about to start an anticoagulant for stroke prevention, warfarin is fraught with very considerable hazard for bleeding early on—not less than about a 3.5% risk of major bleeding per month for at least a five-year window," Dorian noted, citing an Ontario study of patients over age 65. It showed that in the first 30 days after starting warfarin, the risk of hospitalization for a major bleed was as high as 16% for patients with a high CHADS2 score.
While taking an anticoagulant, patients who are unfortunate enough to have a major bleed requiring hospitalization are more likely to die if they were taking warfarin as opposed to a newer agent, he pointed out.
The newer agents represent a viable alternative, he stated. They have a 1% "small but not trivial" absolute benefit over warfarin—similar to the size of other benefits in cardiovascular medicine, such as that of tissue plasminogen activator (tPA) over streptokinase. The risk of intracranial hemorrhage is lower with the newer agents than with warfarin. Patients are also less likely to discontinue dabigatran(Pradaxa, Boehringer Ingelheim) than warfarin.
For all these reasons, he argued, warfarin should be considered obsolete.
A second opinion . . .
Not so fast, Mitchell declared. He presented a graph based on data from the Prevention of Thromboembolic Events – European Registry in Atrial F... (PREFER in AF), 18 months after the 2010 European Society of Cardiology guidelines placed the newer oral anticoagulants on a par with warfarin for stroke prevention for some patients with AF—long enough for practice habits to begin changing. This showed that "in every country, including Germany where [novel oral anticoagulants] NOACs are reimbursed, the vast majority of anticoagulants prescribed for this purpose are for warfarin," he said. The ratio of vitamin-K-antagonist prescriptions to novel-oral-anticoagulant prescriptions was 13:1.
"There are some patients whose preferred oral anticoagulant should be warfarin," he stressed and went on to enumerate which ones.
First, findings from the Dabigatran Etexilate in Patients With Mechanical Heart Valves (RE-ALIGN) trial show that "clearly we should not be using these newer agents—we should be using warfarin—in patients with mechanical prosthetic heart valves." Based on the Central Registry of the German Competence Network on Atrial Fibrillation (AFNET) database, about 5.1% of patients with AF have valvular AF.
Other patients who should receive warfarin instead of the newer drugs include those with rheumatic mitral valvular disease (3.7% of patients with AF), hyperthyroidism (6.7%), or estimated creatinine clearance <30 mL/min (3.7%). Therefore, at least 20% of AF patents do not qualify for the newer agents, he summarized.
Moreover, if good INR is attained while taking warfarin, the enhanced effectiveness with the newer oral anticoagulants vs warfarin disappears, the Randomized Evaluation of Long-Term Anticoagulant Therapy (RE-LY) study showed.
Finally, warfarin is not "dead" because the new drugs are so much more expensive. "I've tried not to talk about cost-effectiveness, because that's not how doctors think when . . . standing in front of a patient," Mitchell said. However, based on an analysis of time in the therapeutic range in subgroups of RE-LY data, the number needed to treat to prevent one stroke or thromboembolism in the patients enrolled by the quartile of RE-LY enrolling centers with the best INR control was 1429; the excess cost of dabigatran without INRs over warfarin with INRs for one year is $3000; so the cost to prevent one stroke in such patients is $4 million.