Month: August 2012

Scarring seen on MRI may predict ICD benefit better than assessment of LVEF

 

Myocardial scarring assessed by MRI is an independent predictor of poor outcomes in implantable cardioverter defibrillator (ICD) candidates with low left ventricular ejection fraction (LVEF), new trial results show.

Currently, measuring LVEF is the most common method for identifying which patients are most likely to need an implantable defibrillator to prevent sudden cardiac death, but sudden cardiac death is usually caused by ventricular tachyarrhythmia, so LVEF is only an indirect measure sudden cardiac death risk. About 70% of patients suffering sudden cardiac death have a preserved LVEF, and studies show that only one death is prevented for every 14 to 18 patients with ventricular dysfunction receiving an ICD, according to the principle investigator of this new trial,  Dr Igor Klem (Duke University) and colleagues.

Klem and colleagues used MRI to evaluate myocardial scarring in 137 patients being evaluated for possible ICD placement for prevention of sudden cardiac death. Results of their study are published in the July 31, 2012 issue of the Journal of the American College of Cardiology.

Over a median follow-up of two years, 39 of the patients died and/or had an appropriate ICD discharge for a sustained ventricular tachyarrhythmia.  As previous trials have shown, the rate of adverse events increased steadily with decreasing LVEF, but there was a big difference in risk between those with a scar greater than 5% of left ventricular mass and those with less scarring (hazard ratio 5.2). A multivariable Cox proportional analysis showed that scar size was an independent predictor of adverse outcomes.

Among patients with LVEFs >30%, those with scarring over 5% of the left ventricle were 6.3 times as likely to die or suffer a sustained ventricular tachyarrhythmia as those with scarring under 5%. Among patients with an LVEF <30%, those with scarring greater than 5% were 3.9 times as likely to die or suffer a sustained ventricular tachyarrhythmia as those with minimal or no scarring.

Patients with an LVEF >30% but significant scarring had the same risk as all patients with an LVEF <30%. Patients with an LVEF <30% and minimal or no scarring had a similar risk to all patients with an LVEF >30%.

Klem I, Weinsaft J, Bahnson T, et al. Assessment of myocardial scarring improves risk stratification in patients evaluated for cardiac defibrillator implantation. J Am Coll Cardiol 2012; 60:408-20.

 

New Recommendations on Stroke Prevention in Atrial Fibrillation

The American Heart Association (AHA)/American Stroke Association (ASA) advisory on stroke prevention in atrial fibrillation has released a new scientific advisory on use of the new oral antithrombotic agents to prevent stroke in patients with nonvalvular atrial fibrillation.

The update recommends that, along with warfarin and dabigatran (Pradaxa, Boehringer Ingelheim), already recommended for this indication, rivaroxaban (Xarelto, Bayer/Johnson & Johnson), and apixaban (Eliquis, Pfizer/Bristol-Myers Squibb) are also indicated to prevent a first or recurrent stroke in patients with nonvalvular AF.

Some of the new recommendations include:

  • Warfarin, dabigatran, apixaban, and  rivaroxaban are all indicated for the prevention of first and recurrent  stroke in patients with nonvalvular AF. “The selection of an agent  should be individualized on the basis of risk factors, cost, tolerability,  patient preference, potential for drug interactions, and other clinical  characteristics, including time in INR therapeutic range if the patient   has been taking warfarin.”
  • Dabigatran 150 mg twice daily is an  “efficacious alternative” to warfarin for the prevention of  first and recurrent stroke in patients with nonvalvular AF and at least  one additional risk factor who have creatinine clearance (CrCl) >30      mL/min.
  • Use of dabigatran 75 mg twice daily may be  considered in patients with AF and at least one additional risk factor who  have a low CrCl, in the range of 15 to 30 mL/min. Dabigatran is not  recommended in patients with more severe renal failure (CrCl <15  mL/min).
  • Apixaban 5 mg twice daily is an  “efficacious alternative” to aspirin in patients with nonvalvular AF deemed unsuitable for vitamin-K-antagonist therapy who have  at least one additional risk factor and no more than one of the following      characteristics: age >80 years, weight <60 kg, or serum creatinine   >1.5 mg/dL.
  • Apixaban 2.5 mg twice daily may be considered      as an alternative to aspirin in patients with nonvalvular AF deemed  unsuitable for vitamin-K-antagonist therapy who have at least one  additional risk factor and more than two of the following criteria: age  >80 years, weight <60 kg, or serum creatinine >1.5 mg/dL.
  • Apixaban 5 mg twice daily is a  “relatively safe and efficacious alternative” to warfarin in  patients with nonvalvular AF deemed appropriate for vitamin-K-antagonist  therapy who have at least one additional risk factor and no more than one  of the following characteristics: age >80 years, weight <60 kg, or serum creatinine >1.5 mg/dL.
  • Although its safety and efficacy have not been  established, apixaban 2.5 mg twice daily may be considered as an alternative to warfarin in patients with nonvalvular AF deemed appropriate for vitamin-K-antagonist therapy who have at least one additional risk factor and more than two of the following criteria: age >80 years,  weight <60 kg, or serum creatinine >1.5 mg/dL. Apixaban should not      be used if the CrCl is <25 mL/min.
  • In patients with nonvalvular AF who are at moderate to high risk of stroke (prior history of transient ischemic attack [TIA], stroke, or systemic embolization or more than two additional risk factors), rivaroxaban 20 mg/day “is reasonable” as an alternative  to warfarin.
  • In patients with renal impairment and  nonvalvular AF who are at moderate to high risk of stroke (prior history  of TIA, stroke, or systemic embolization or more than two additional risk  factors), with a CrCl of 15 to 50 mL/min, 15 mg of rivaroxaban daily may  be considered, but its safety and efficacy have not been established.   Rivaroxaban should not be used if the CrCl is <15 mL/min.
  • The safety and efficacy of combining  dabigatran, rivaroxaban, or apixaban with an antiplatelet agent have not  been established.

 Source: The Heart.Org

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