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ATRIAL FIBRILLATION IN THE ER

ATRIAL FIBRILLATION IN THE ER. MAGDI SAMI, MD,FRCP(C), FACC. OBJECTIVES. DIAGNOSIS OF DIFFERENT TYPES OF AF AND DIFFERENTIATE FROM OTHER ARRHYTHMIAS ACUTE AND LONG-TERM MANAGEMENT OF AF: WHEN TO CARDIOVERT? ELECTRIC VS CHEMICAL WHEN TO GO FOR RATE-CONTROL? ACUTE & LONG-TERM. CASE 1.

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ATRIAL FIBRILLATION IN THE ER

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  1. ATRIAL FIBRILLATION IN THE ER MAGDI SAMI, MD,FRCP(C), FACC

  2. OBJECTIVES • DIAGNOSIS OF DIFFERENT TYPES OF AF AND DIFFERENTIATE FROM OTHER ARRHYTHMIAS • ACUTE AND LONG-TERM MANAGEMENT OF AF: • WHEN TO CARDIOVERT? • ELECTRIC VS CHEMICAL • WHEN TO GO FOR RATE-CONTROL? • ACUTE & LONG-TERM

  3. CASE 1 Mr. J.V. 60 y old. -Nov.98: first presentation with PAF at age 56. no previous cardiac history except rec. palpitation, no known CRF. -Physical exam: normal -ECG (show) • Echocardiogram: normal • Lab: SMA normal, high cholesterol

  4. What next?

  5. Methods to Restore Sinus Rhythm • A. Spontaneous cardioversion • B. Electrical cardioversion • 1.Transthoracic • 2. Internal • a. intracardiac • b. transesophageal • c. epicardial • Pharmacological cardioversion • 1.Class 1A or 1C • 2. Class III

  6. Pharmacological Conversion • Class 1A(quinidine, procainamide, disopyramide) • Class 1C(propafenone, flecainide) • Class III(amiodarone, sotalol, ibutilide, dofetilide) • Others Digoxin, beta-blockers, calcium blockers not effective (verapamil may prevent AF recurrences after cardioversion)

  7. Ibutlide • Unique iv antiarrhythmic drug • Classified as Class III according to Vaughan Williams Classification • Little effect on conduction in normal cardiac tissue

  8. Ibutilide Electrophysiologic Effects • No clinically significant effect on QRS • Produces a dose related prolongation of the QT interval • Prolongation of QT interval is similar in men and women • Prolongs action potential duration and effective refractory periods in both atria and ventricles

  9. Ibutilide Electrophysiologic Effects • Lengthens effective refractory period in both atrium and ventricle • Enhances slow Na+ inward plateau current and blocks delayed-rectifier outward K+ current • Maintains Class III effects even at rapid heart rates

  10. Ibutilide Mechanism of Action Slow Na  (Ibutilide) Ca Na plateau K+ (other Class III) Repolarization V Max + - APD Action Potential Duration QRS QT T N

  11. Ibutilide Hemodynamic Effects • No clinically significant effects on cardiac output, mean pulmonary arterial pressure or capillary wedge pressure in patients with ejection fractions > 35 or < 35%

  12. Ibutilide Pharmacokinetics • Similar in all patients regardless of AF or AFL, age, sex, ejection fraction, occurrence of polymorphic ventricular tachycardia or the concomitant use of digoxin, calcium blockers or beta blockers.

  13. Ibutilide Pharmacokinetics • Pharmacokinetics is highly variable among subjects but linear to dose of 0.01 mg/kg – 0.1 mg/kg (0.6 – 6 mg) • Initial distribution half-life is 1.5 min. and elimination half-life averages 6 h • Clearance is primarily hepatic metabolism

  14. Ibutilide Pharmacokinetics • Moderate protein binding (40%) • 8 metabolites – none of which contribute to its pharmacological effects • 82% of dose excreted in urine • 19 % in faeces

  15. Ibutilide Indications and Clinical Use • Ibutilide (CORVERT®) is indicated for the rapid conversion of atrial fibrillation or atrial flutter to sinus rhythm. CORVERT™ should be considered an alternative to electric cardioversion. CORVERT product monograph

  16. Ibutilide Arrhythmia Conversion: Repeat Dose Study Stambler B.S. et al. Circulation 1996; 94:1613

  17. Arrhythmia Conversion: Ibutilide vs. Procainamide Volgman A.S. et al. J. Am..Coll. Card 1998: 31: 1414

  18. Ibutilide Predictors of Arrhthmia Termination * *P< 0.05 Stambler BS. et al. Circulation 1996; 94:1613

  19. Ibutilide Proarrythmia % and number of patients with proarrhythmias possibly causally related to ibutlide in three placebo controlled trials CORVERT product monograph

  20. Polymorphic VT Risk Assessment:Independent Predictors of Risk • Female gender • - 13.2% vs. 3.8% (P = 0.0046) • History of heart failure • 11.4% vs. 3.6% (P = 0.0305) • Slower heart rate • 78 ± 18 vs. 95 ± 26 bpm (P = 0.0348) • Nonwhite race • 15.9% vs. 3.6% (P = 0.0383) Stambler BS. et al. Circulation 1996; 94:1613

  21. Ibutilide Dosing CORVERT product monograph

  22. Ibutilide Summary • Conversion efficacy - AFL 60 – 80%, AF 30 – 50% - AF  arrhythmia duration (46% AF < 7 days vs. 18% AF  7 days) • Superior to iv procainamide • Mean time to termination < 30 min. • Lowers atrial DFT, prolongs ARP • Enhances efficacy of rapid pacing termination of AFL • Proarrhythmia risk (torsade de pointes) ˜ 2% sustained, 3% non-sustained

  23. Ibutilide Electrical vs. Pharmacological Conversion * • K + < 4.0mEq/L • HR < 60 bpm • QTc > 440ms • Receiving Class I or III AAD • Hx torsade de pointes or polymorphic VT • Acute MI, unstable angina • Renal failure • Hepatic failure • Pregnancy or breast feeding • SHP < 90 mmHg • Age < 18 years • ECG monitoring  4h post infusion unavailable Cardioversion Candidate Atrial Fibrillation Atrial Flutter YES YES Duration < 7d YES NO DC Cardioversion iv Ibutilide YES Contraindication * to Ibutilide? NO

  24. CASE 2 • DF 66 Y OLD M HYPERTENSIVE DIABETIC • 3 DAYS HISTORY OF FEELING SHORT OF BREATH AND PALPITATIONS • WAS RELUCTANT TO COME TO ER, WAITED TO SEE HIS GP WHO IMMETIATELY REFERRED HIM TO ER • INITIAL EXAM SHOWS FAST IRREG. HR, BP 188/90, JVD 10 cm, BILAT. BASAL CREPS.

  25. MANAGEMENT QUESTIONS • CV OR RATE CONTROL? • IF CV WHAT TEST TO YOU NEED FIRST? • IS CHEMICAL CARDIOVERSION SAFER THAN ELECTRIC? • IF RATE CONTROL IS CHOSEN HOW TO PROCEED? • AFTER THE ACUTE TREATMENT WHAT NEXT?

  26. WHAT IF THE PATIENT HAD PRESENTED WITH A REGULAR TACHYCARDIA? SEE NEXT SLIDE

  27. HOW WOULD YOU TREAT THE PATIENT NOW?

  28. CASE 3 • 24 Y OLD PREGNANT F 33 WKS • PRESENTING WITH SEVERE PALPITATIONS AND CHEST PAIN • HER ARRHYTHMIA STARTED FOR THE FIRST TIME SHORTLY AFTER HER SECOND CUP OF COFFEE AND HAS BEEN GOING ON FOR ONE HOUR.

  29. HOW WOULD YOU TREAT THIS PATIENT?

  30. CASE 4 • 64 Y OLD HYPERTENSIVE F WHO WAS TAKING SOTALOL 80 mg BID FOR PAF • SHE RECENTLY VISITED HER GP WHO FOUND HER BP TO BE 160/90 • GP STARTED HER ON 25 MG OF HCTZ QD • SINCE THEN PATIENT HAS HAD RECURRENT SYNCOPES AND PRESENTED TO ER

  31. Recommendations for Management of Atrial Fibrillation < 48 Hours Adapted from Golzari H. Ann Intern Med. 1996;125:311-323. Control ventricular rate Consider antithrombotic therapy Observe for spontaneous conversion Prompt electrical or pharmacologic conversion Antiarrhythmic therapyif No antiarrhythmic therapyif Unstable hemodynamics or increased LA size Stable hemodynamics, or first episode, n LA

  32. Recommendations for Management of Atrial Fibrillation > 48 Hours Control ventricular rate Start antithrombotic therapy (heparin and/or warfarin or aspirin) Adapted from Golzari H. Ann Intern Med. 1996;125:311-323. Duration < 1 year Duration > 1 year or Warfarin therapy 3-4 weeks Cardioversion or pharmacologic conversion Antiarrhythmic therapy if No antiarrhythmic therapy if Stable hemodynamics, or first episode, n LA Unstable hemodynamics or increased LA size Continue warfarin 1-2 monthsMonitor for recurrences Chronic antithrombotic therapy Assure control of ventricular rate

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