DR RICHARD BOGLE PHD FRCP FESC FACC DHMSA CONSULTANT CARDIOLOGIST
  • Home
  • Blog
  • NHS Practice
    • NHS Practice
    • St Helier Hospital
    • Epsom Cardiac Day Unit
    • St George's Hospital Radial Lounge
    • Echocardiography
  • Biography
    • Qualifications
    • About me >
      • Curriculum vitae
    • Appraisal and Revalidation
    • BCIS Angioplasty Audit
    • Publications
    • Recent abstracts
    • Research
    • Charitable activity
  • The Heart
    • Cardiac Investigations >
      • AliveCor ECG monitor
      • Guide to investigations for suspected angina
      • CT calcium scoring
      • Electrocardiogram (ECG)
      • Exercise treadmill test
      • Echocardiogram
      • Valve disease
      • Coronary Angiography
      • Pressure Wire Studies
      • Intra-vascular Ultrasound
    • Arrhythmias >
      • Atrial fibrillation >
        • Stroke Risk in AF
        • New Oral Anticoagulants
        • Presentations on AF
      • Atrial flutter
      • Pre-excitation syndromes
      • Ventricular ectopic beats
      • Ventricular arrhythmias
      • Pacemaker
      • DC Cardioversion
    • Cardiomyopathy
    • Coronary heart disease >
      • Cardiac syndrome X
      • Coronary Angioplasty
      • Coronary bypass surgery
    • Dizziness and blackouts
    • Fitness to fly
    • Fitness to drive
    • Heart Failure
    • Hypertension >
      • Patients guide to blood pressure medication
      • Home blood pressure monitors
      • Hypertension diet
      • Laragh's method
      • Renal sympathetic ablation for hypertension
      • Conn's Syndrome
    • Heart Screening >
      • Sports Cardiology
      • Cardiovascular Disease Risk
    • Medications >
      • Glyceryl trinitrate
    • Patient information leaflets
  • News and Links
  • Miscellany
    • History of Medicine
    • History of Coronary Angiography and Angioplasty
    • Stamps in Cardiology
    • A History of Medicine in 100 Objects
    • BSE Acceditation Course Introduction
    • BSE Acceditation Course Physics
    • BSE Acceditation Course Anatomy and Function
    • BSE Acceditation Course Mitral
    • BSE Acceditation Course Aortic
    • BSE Acceditation Course Congenital
    • BSE Acceditation Course Pericardium
    • RACPC Form
    • Cardiology Teaching St Helier Hospital

Looking for a needle in a haystack

25/6/2014

0 Comments

 
Picture
Atrial fibrillation (AF) is an important and preventable cause of stroke. If AF is detected then a patient will usually be advised to go onto anticoagulation which reduces the risk of stroke by about 70%.

Some patients will have paroxysmal AF (PAF) which comes and goes interspersed by normal heart rhythm. PAF is defined as 30 seconds or more of AF and the risk of stroke is the same as with persistent AF. The ASSERT trial tried to determine how much PAF is necessary to increase the stroke risk and the results suggest that as little as 6 minutes of AF over a period of 3 months increases stroke risk by 2.5 fold.

After a stroke it is routine to do an 12 lead ECG to assess the cardiac rhythm and if this is normal then a longer period of heart monitoring would be performed to look for evidence of PAF. The question is however how long should the monitoring be done for to stand a good chance of detect PAF? Is 24h enough, or should it be a week or a month or even longer.

Two papers published this week in the New England Journal of Medicine have tried to address this question. The EMBRACE study compared a standard approach with 24h ECG monitor to a 30 day cardiac event recorder. 572 patients with apparently normal heart rhythm with a previous stroke in the last 6 months were randomly assigned to either 24h or 30 days of monitoring. In the group monitored for 24h just 3.2% of people had AF detected whereas in the group monitored for 30 days AF was detected in 16.1%. This meant that for every 8 people screened for the longer period 1 extra case of PAF was detected. Once AF was detected it led to a change of treatment for the patients with antiplatelet drugs being switched to anticoagulants which are much more effective at reducing recurrent stroke.

In the CRYSTAL AF study patients were randomly assigned to either having a loop recorder implanted or standard care. After 6 months PAF has been detected in 8.9% of patients with the ILR compared to 1.4% in the control group and by 12 months this had increased to 12.4% in the ILR and 2% in the control group.  There is a difference in the AF detection rate between the two studies which is probably due to the EMBRACE trial having an older population with more patients suffering from hypertension and diabetes. What is clear however is that the longer the period of monitoring the more cases of undiagnosed AF are detected. Since this has a profound effect on management of the patient these findings are very important.

There are some practical problems with monitoring patients for 30 days due to the ability to comply with the need for electrodes of the chest. The EMBRACE study used a dry electrode chest belt which has better tolerability and less skin irritation than traditional electrodes. The ILR technique is attractive particularly and with the advent of virtually injectable devices such as the REVEAL LINQ  but the cost of these devices might be seen as prohibitive if the technology was applied to every patient with a stroke. Perhaps though when a cost-effectiveness analysis is performed and the number of recurrent strokes prevented is factored in this type of monitoring device would pay for itself. If you take the parallel situation of a patient with a heart attack we think nothing of implanting several drug eluting stents which cost thousands of pounds in order to prevent a recurrent admission to hospital with chest pain or a non-fatal heart attack. What then of spending a similar amount to prevent a stroke?

These new studies are challenging the current practice of accepting a short period of monitoring when looking for AF. In this situation absence of evidence of AF should not be taken as evidence of absence and it looks as though a more prolonged period of monitoring is likely to be beneficial.




0 Comments

Your comment will be posted after it is approved.


Leave a Reply.

    RSS Feed

    Picture

    Dr Richard Bogle

    The opinions expressed in this blog are strictly those of the author and should not be construed as the opinion or policy of my employers nor recommendations for your care or anyone else's. Always seek professional guidance instead.

    Archives

    August 2023
    November 2019
    March 2016
    February 2016
    May 2015
    April 2015
    March 2015
    February 2015
    January 2015
    December 2014
    November 2014
    October 2014
    September 2014
    August 2014
    July 2014
    June 2014
    May 2014
    April 2014
    March 2014
    February 2014
    January 2014
    November 2013
    October 2013
    August 2013
    July 2013
    June 2013
    May 2013
    April 2013
    March 2013
    February 2013
    January 2013

    Categories

    All
    Ablation
    Acute Coronary Syndromes
    Acute Coronary Syndromes
    Adherence
    Angioplasty
    Anticoagulants
    Arrhythmia
    Association
    Atherosclerosis
    Atrial Fibrillation
    Auenbrugger
    Bergamot
    Brugada
    Calcium Channel Blockers
    Cancer
    Cardiovascular Risk
    Chest Pain
    Cholesterol
    Cleveland Street
    Clinical Examination
    Colchicine
    Compliance
    Concordance
    Congenital Heart Disease
    Coronary Artery Disease
    Coronary Artery Disease
    C-reactive Protein
    Decision Aids
    Diet
    Ectopics
    Eggs
    Ezetimibe
    Frailty
    Frank's Sign
    Guidelines
    Hawthorne Effect
    Heart Failure
    History Of Medicine
    Hypertension
    ICD
    Internet
    Interventional Cardiology
    Joseph Rogers
    Lipids
    Malaria
    Marathon
    Medicines
    Nice Guidelines
    Nitrovasodilators
    NOAC
    Nudge
    Nutrition
    OCT
    Palpitations
    Pharmacy
    Pressure Wire
    Proteus
    Salt
    Smoking
    Spironolactone
    Statins
    Statistics
    Stent
    Stress
    Stroke
    Syndrome X
    Takotsubo
    Valve-disease
    Vein Grafts
    Ventricular Ectopics
    VF/VT
    Warfarin
    Weekend Working
    Workhouse

    View my profile on LinkedIn
Return to home page

Privacy Statement
Disclaimer
© Dr Richard Bogle 2020
patient feedback
Photo used under Creative Commons from peddhapati
  • Home
  • Blog
  • NHS Practice
    • NHS Practice
    • St Helier Hospital
    • Epsom Cardiac Day Unit
    • St George's Hospital Radial Lounge
    • Echocardiography
  • Biography
    • Qualifications
    • About me >
      • Curriculum vitae
    • Appraisal and Revalidation
    • BCIS Angioplasty Audit
    • Publications
    • Recent abstracts
    • Research
    • Charitable activity
  • The Heart
    • Cardiac Investigations >
      • AliveCor ECG monitor
      • Guide to investigations for suspected angina
      • CT calcium scoring
      • Electrocardiogram (ECG)
      • Exercise treadmill test
      • Echocardiogram
      • Valve disease
      • Coronary Angiography
      • Pressure Wire Studies
      • Intra-vascular Ultrasound
    • Arrhythmias >
      • Atrial fibrillation >
        • Stroke Risk in AF
        • New Oral Anticoagulants
        • Presentations on AF
      • Atrial flutter
      • Pre-excitation syndromes
      • Ventricular ectopic beats
      • Ventricular arrhythmias
      • Pacemaker
      • DC Cardioversion
    • Cardiomyopathy
    • Coronary heart disease >
      • Cardiac syndrome X
      • Coronary Angioplasty
      • Coronary bypass surgery
    • Dizziness and blackouts
    • Fitness to fly
    • Fitness to drive
    • Heart Failure
    • Hypertension >
      • Patients guide to blood pressure medication
      • Home blood pressure monitors
      • Hypertension diet
      • Laragh's method
      • Renal sympathetic ablation for hypertension
      • Conn's Syndrome
    • Heart Screening >
      • Sports Cardiology
      • Cardiovascular Disease Risk
    • Medications >
      • Glyceryl trinitrate
    • Patient information leaflets
  • News and Links
  • Miscellany
    • History of Medicine
    • History of Coronary Angiography and Angioplasty
    • Stamps in Cardiology
    • A History of Medicine in 100 Objects
    • BSE Acceditation Course Introduction
    • BSE Acceditation Course Physics
    • BSE Acceditation Course Anatomy and Function
    • BSE Acceditation Course Mitral
    • BSE Acceditation Course Aortic
    • BSE Acceditation Course Congenital
    • BSE Acceditation Course Pericardium
    • RACPC Form
    • Cardiology Teaching St Helier Hospital