Efficacy of pretreatment with rhythm control drugs to improve the acute success rate of electrical cardioversion of atrial fibrillation

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Efficacy of pretreatment with rhythm control
drugs to improve the acute success rate of
electrical cardioversion of atrial fibrillation
University at Buffalo
The state University of New York

• Muhammad S Ajmal MBBS
• Aravind Herle MD FACC

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Atrial fibrillation (AF)

• A supraventricular tachyarrhythmia characterized
  by uncoordinated atrial activation with
  consequent deterioration of atrial
  mechanical function.
• The estimated prevalence of AF is 0.4 to 1 in
  the general population, increasing with age to 8
  in patients older then 80.
• 2.2 million people in USA and 4.5 million people
  in Europe has AF.

Fuster, V. et al. Circulation 2006114e257-e354
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Clinical manifestations

• Available data suggests that quality of life is
  considerably impaired in patients with AF
  compared to age-matched controls.
• Asymptomatic phase.
• Subjective symptoms Fatigue, palpitations, chest
  pain, dyspnea, lightheadedness or syncope.
• Exacerbation of heart failure.
• Embolic complications including Stroke.

Fuster, V. et al. Circulation 2006114e257-e354
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Management

• Strategic objectives
• Prevention of thromboembolism.
• Rate control.
• Correction of rhythm disturbance.

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Prevention of thromboembolism.

• Studies have shown increase risk of stroke in
  patients with AF.
• The simplest risk assessment scheme is
  the CHADS2 score. Studies showed clear
  relationship between CHAD2 score and risk of
  stroke.

European Heart Journal (2010) 31, 2369-2429
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Rate or Rhythm control

• Randomized clinical trials have shown rate
  control to be
• at least non- inferior to rhythm control
  therapies.
• Choice must be individualized, depending on the
  symptoms, patient preferences, comorbid
  conditions, and the ongoing response to
  treatment.
• Rate control is a reasonable initial therapy for
  patients with persistent AF .

European Heart Journal (2010) 31, 2369-2429
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Rhythm Control

• Rhythm control is preferable in following
  conditions
• Symptomatic AF not responding to rate control.
• Congestive heart failure.
• Patient preference to achieve sinus rhythm,
  specially in younger population who are
  intolerant to AF.
• Unable to tolerate rate control agents.

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Rhythm control

• Pharmacological cardioversion.
• Electrical cardioversion.

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Pharmacological cardioversion

• Recent meta-analysis of 45 clinical trials,
  comprising of 12559 patients showed that class
  1A,1C and 3 drugs increase the likelihood of
  maintaining sinus rhythm but increase adverse
  events.
• Mortality was low in most studies(0-4.4) but
  Class 1A drugs were associated with increased
  mortality.

Cochrane Database Syst Rev 20074CD005049
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2011 Writing Group Members, et al. Circulation
2011123104-123
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Electrical cardioversion

• Delivery of an electrical shock synchronized with
  the intrinsic activity of the heart by sensing
  the R wave of the EKG to ensure that electrical
  stimulation does not occur during the vulnerable
  phase of the cardiac cycle.
• Performed under light anesthesia with
  prophylactic anti-coagulation.
• Success rate in literature varies between 70-99
  depending upon the definition of success.
• 
  
  
  

Fuster, V. et al. Circulation 2006114e257-e354
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Review of Literature

• Factors that predispose to AF recurrence
• Duration of AF before electrical cardioversion.
• Number of previous recurrences.
• Increased left atrial size.
• Coronary heart disease or pulmonary or mitral
  valve disease.

European Heart Journal (2010) 31, 2369-2429
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ACC/AHA/ESC Guidelines Regarding Pharmacological
Enhancement of Electrical Cardioversion.

• Pretreatment with Amiodarone, Flecainide,
  Ibutilide, Propafenone and Sotalol can be useful
  to enhance the success of direct-current
  cardioversion and prevent recurrent atrial
  fibrillation. Class 2A (Level of evidence B).
• Efficacy of Beta blockers, Verapamil, Diltiazem,
  Disopyramide, Procainamide or Dofetilide to
  enhance the success of direct current
  cardioversion is uncertain. Class 2B (Level of
  evidence C).

Fuster, V. et al. Circulation 2006114e257-e354
European Heart Journal (2010) 31, 2369-2429
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Review of Literature

• The role of Antiarrhythmic drugs to enhance the
  acute success rate of electrical cardioversion
  remains unclear.
• No large randomized clinical trials.
• Few small trials showed conflicting evidence that
  pretreatment with class 1c and class 3 agents
  enhance the acute success of electrical
  cardioversion of AF.
• Comparative efficacy of various drugs used for
  pretreatment is unknown.

European Heart Journal (2010) 31, 2369-2429
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Study Objectives

• Acute success rate of electrical cardioversion of
  AF at Mercy Hospital?
• Efficacy of pretreatment with rhythm control
  drugs to improve the acute success rate of
  electrical cardioversion of AF.
• Compare efficacy of various rhythm control drugs
  used for pretreatment.
• Identify other predictors of successful
  electrical cardioversion of AF.

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Study Design.

• Retrospective chart review.
• IRB Approval Consent waived.
• HIPAA compliance.
• Inclusion criteria
• All patients who underwent electrical
  cardioversion for AF during 2007-10 were
  included in the study.
• Exclusions
• Patients in atrial flutter or any other atrial
  arrhythmias were excluded from the study.

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Study Design

• Patients were divided into two groups. One group
  received pretreatment with rhythm control drugs
  before electrical cardioversion and other group
  did not.
• Rhythm control drugs included class 1c or class 3
  Antiarrhythmic drugs.
• Pretreament was defined as initiation of rhythm
  control drugs any time before the procedure.

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Study Design
Total cases of electrical cardioversion at Mercy
Hospital during 2007-10
Patients in atrial flutter at time of
cardioversion.
Excluded from atrial fibrillation group.
Patients with atrial fibrillation that underwent
electrical cardioversion.
Patients who did not receive pretreatment.
Patients who received pretreatment.
Un-successful cardioversion
Successful cardioversion
Successful cardioversion
Un-successful cardioversion
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Study Design

• Following additional data was collected about
  each patient
• Age.
• Sex.
• Clinical setting.
• Duration of AF.
• Persistent or paroxysmal AF.
• Hx of Hyperthyroidism.
• Hx of COPD.

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Study Design

• Size of left atrium.
• Left ventricular ejection fraction.
• Hx of Hypertension.
• Anti-coagulation status.
• TEE before procedure.
• Number of shocks.
• Energy settings of the shock.

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Baseline Characteristics.

• Both groups were closely matched.
• Only statistically significant difference was
  Duration of AF longer then 6 months in
  pretreatment group compared with the other group
  (83 and 68 respectively). P0.0155

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Successful electrical cardioversion

• Acute conversion to sinus rhythm confirmed by
  post-cardioversion EKG.
• Maintenance of rhythm for at least 2 hours or
  until the patient left the cath lab.
• IRAF and sub acute recurrences within first 2
  hours were included as failure of cardioversion.

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Hypothetical illustration of cardioversion
failure.
Fuster, V. et al. Circulation
2006114e257-e354
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Results
Total cases of electrical cardioversion. 304
Patients in atrial flutter 49
Excluded from atrial fibrillation group.
Patients in atrial fibrillation. 255
Patients who did not receive pretreatment 154
Patients who received pretreatment 101
Un-successful cardioversion 12
Successful cardioversion 89
Successful cardioversion 125
Un-successful Cardioversion 29
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Results.

• Overall success rate of electrical cardioversion
  of AF at Mercy Hospital 84.
• Success rate in patients who received
  pretreatment 88
• Success rate in patients with no pretreatment
  81
• This difference was not statistically
  significant. (p0.1647).

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Results

• Acute Success rate of electrical cardioversion of
  Atrial flutter was 96.

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Success rates of individual Antiarrhythmic
drugs
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Efficacy of Dronedarone in pharmacological
enhancement of electrical cardioversion

• Dronedarone, a newer class 3 Antiarrhythmic drug
  had lower success rate when used for pretreatment
  compared with Amiodarone and Propafenone. This
  difference was statistically significant. (
  P0.0261 and P0.0135 respectively).
• Dronedarone sub-group also had a lower success
  rate compared with Sotalol, Flecainide and
  Dofetilide, but the difference was not
  statistically significant.

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Table 2-3).Baseline characteristics of Patients
in Dronedarone and Amiodarone/Propafenone
sub-groups did not show any statistically
significant differences in terms of duration of
atrial fibrillation, size of left atrium and
LVEF.
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Efficacy of Dronedarone

• DAFNE trial showed that in patients with
  persistent AF, Dronedarone converted only 5.8 to
  sinus rhythm (3.1 converted with placebo) and
  did not improve the acute success rate of
  electrical cardioversion.
• DIONYSOS trial showed that Dronedarone was
  inferior to Amiodarone in preventing recurrence
  of AF including unsuccessful electrical
  cardioversion but was better tolerated.

Eur Heart J (2003) 24 (16) 1481-1487.
J Am Coll Cardiol, 2009 541089-1095
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Other predictors of Successful electrical
cardioversion
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Conclusions

• Pretreatment with class 1c or 3 Antiarrhythmic
  drugs failed to show statistically significant
  evidence of enhancing the acute success rate of
  electrical cardioversion of AF. But, a
  confounding bias exist.
• Pretreatment with Dronedarone was inferior to
  Amiodarone and Propafenone in improving the acute
  success rate of electrical cardioversion of AF.
• Size of left atrium is inversely related to the
  likelihood of successful electrical cardioversion
  and this association is statistically
  significant.

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Limitations of the study

• Retrospective study.
• Small sample size for each sub-groups.
• Limited follow up after electrical cardioversion
  to determine the probability of maintenance of
  sinus rhythm.

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Acknowledgement

• Dr. Aravind Herle.
• Dr. Khalid J Qazi.
• CHS IRB Team.
• HIM staff.

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Questions
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Thank You