Atrial Fibrillation

• Issues in Management of AF

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• Should We Maintain Sinus Rhythm?
• The AFFIRM trial
• The SAFE-T trial- amiodarone vs sotalol vs placebo

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• Anticoagulation in AF
  • Risk of Thromboembolism-CHADS2
  • "Moderate Risk" Patients
  • "High-Risk" Patients
  • Secondary Prevention
  • Target INR level for AF patients
  • Maintain INR in theurapeutic range

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• Clopidogrel
  • Anticoagulation slightly better than Clopidogrel with Aspirin
  • Clopidogrel with Asprin better than Aspirin alone for those not eligible for anticoagulation

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• Cardioversion
• Role of Transoesophageal Echo in Cardioversion

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• Use of ACE-inhibitors or ARBs
• ACE-inhibitors may reduce the risk of recurrent PAF in those with lone PAF

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• Non-Pharmacological Therapy
• Options

How much benefit do high-risk patients get with anticoagulation with Warfarin?

Analysis of the SPAF II trial results identified subgroups of patients with non-rheumatic atrial fibrillation that seemed to be at higher risk of thromboembolism. Subsequently, the SPAF III trial prospectively compared standard dose warfarin (to maintain INR between 2-3) with low dose warfarin (INR 1.2 to 1.5) plus asprin 325mg/d.

The SPAF III trial defined high risk patients as those who had one of the following risk factors
• being a female aged more than 75 years
• a systolic pressure greater than 160mmHg
• poor left ventricular function
• a prior thromboembolic event.
• NOTE: left atrial enlargement is also recognised as a risk factor for increased risk. This study excluded patients with rheumatic valve disease who are known to be at particularly high risk.

Most participants had more than one risk factor and the average age was 71 years.

The group with low dose warfarin had a high thromboembolic event rate (7.8%) vs standard dose warfarin (2.6%). The annual rate of disabling stroke (5.6% vs 1.7%) and the primary event or vascular death (11.8% vs 6.4%) were also higher with the combination group. In other words, standard dose warfarin was a superior treatment and only about 25 high-risk patients need to be anticoagulated with warfarin, for one year, to prevent one disabling stroke. However, of note, is that if analysis is confined just to high risk patients excluding those that have had prior thromboembolism (see below) than the benefits are slightly less, but still significant.

Major haemorrhage in SPAF III (including intracranial haemorrhage) were similar in the two groups: 2.1 and 2.4%. There is data from other studies which show higher risk of bleeding in the elderly.

Hitesh Patel, Cardiologist
28th August, 2004

Reference

• SPAF III trial. The Lancet 1996; 348:633-38)