PRACTICAL APPROACH TO SVT. Graham C. Wong MD MPH Division of Cardiology Vancouver General Hospital University of British Columbia

Transcription

1 PRACTICAL APPROACH TO SVT Graham C. Wong MD MPH Division of Cardiology Vancouver General Hospital University of British Columbia

2 CONDUCTION SYSTEM OF THE HEART SA node His bundle Left bundle AV node Right bundle

3 IRREGULAR USUAL CLASSIFICATION OF THE SVTs REGULAR ATRIAL FIBRILLATION MULTIFOCAL ATRIAL TACHYCARDIA SINUS TACHYCARDIA ECTOPIC ATRIAL TACHYCARDIA JUNCTIONAL TACHYCARDIA ATRIAL FLUTTER WITH 2:1 BLOCK AV NODAL REENTRY TACHYCARDIA AV REENTRY TACHYCARDIA

4 Mechanisms of supraventricular tachycardia SINUS NODE SINUS TACHYCARDIA ACCESSORY ATRIAL PACEMAKER (S) 1. ATRIAL FLUTTER 2. ECTOPIC ATRIAL TACHYCARDIA (EAT) 3. ATRIAL FIBRILLATION 4. MULTIFOCAL ATRIAL TACHYCARDIA 5. JUNCTIONAL TACHYCARDIA RE-RENTRY 1. AV NODAL REENTRY TACHYCARDIA (AVNRT) 2. AV REENTRY TACHYCARDIA (AVRT)

5 SINUS NODE BLOCK THE SAN PRINCIPLES OF THERAPY ACCESSORY ATRIAL PACEMAKER (S) TARGET THE ACCESSORY PACEMAKER BLOCK PROPAGATION OF THE ATRIAL ARRHYTHMIA THROUGH THE AV NODE RE-RENTRY BLOCK THE RE-ENTRY CIRCUIT

6 Anatomy of the AV Node: Implications for therapy A V V A A A V V A V V V A A A V Suprahissian region Infrahissian region AV node

7 TREATMENT OF SVT BASED ON MECHANISM BLOCK THE SAN BLOCK ACCESSORY PACEMAKER SLOW AVN CONDUCTION BLOCK THE REENTRY CIRCUIT BETA BLOCKER CALCIUM BLOCKER CLASS I OR III ANTIARRHYTHMICS ABLATION TECHNIQUES ANY AV NODAL BLOCKING AGENT ANY AV NODAL BLOCKING AGENT

8 Simple approach to the Regular SVTs Is there a P wave before every QRS? YES Does the P wave look normal? YES SINUS TACHY NO Is the rate close to 150 BPM? NO YES ATRIAL FLUTTER NO ECTOPIC ATRIAL TACHY Are there P waves after the QRS? NO YES JUNCTIONAL TACHYCARDIA AVRT AVNRT

9 LET S GET STARTED

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15 SLOW PATHWAY FAST PATHWAY - Slow conduction - Fast recovery -Bidirectional - Fast conduction - Slow recovery -Bidirectional AV NODE

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28 Atrial fibrillation and mortality: Framingham Age Age Benjamin et al. Circ 1998; 98: N=296 men & 325 women OR 1.5 OR 1.9

29 Functional status in atrial fibrillation: impact of disease and treatment Dorian et al. Can J Cardiol 2006; 22:

30 Classification of Atrial Fibrillation First detected Paroxysmal 7 da (Self terminating) Persistent Persistent >7da-1 yr (Not self-terminating) Permanent Patterns of AF Lone AF young (< 60 yr), no clinical or ECHO evidence of cardiopulmonary disease or hypertension Nonvalvular AF no rheumatic MVD, MV repair, or prosthesis Secondary AF in setting of AMI, peri- or post-operative, myocarditis, hyperthyroid, PE, pneumonia, etc

31 Management NO DECISION TREE STABLE? YES Defibrillate Drugs

32 Can you safely cardiovert acute AF? 2, 3, 4 RULE If in AF for greater than TWO days (or unknown) must anticouagulate (INR 2-3) for THREE weeks before an attempt to cardiovert and then continue coumadin for FOUR weeks afterwards if successful 60% of acute AF convert spontaneously if onset <24 hrs

33 Medications for Acute Cardioversion Rate control Beta blocker metoprolol 5mg IV q5 minutes Rate limiting calcium blocker verapamil 5mg IV q5 minutes x 3 diltiazem 5-10mg IV and 10-15mg/hr IV drip Digoxin 0.5mg IV load and then 0.25mg IV q 6-8hrs x 2 Rhythm control Amiodarone mg IV load and then 1-2g IV/daily Sotalol 40-80mg po BID Propafenone mg po x 1 dose Paroxysmal AFib can revert to NSR spontaneously 30% of the time within 1 day!

34 The Stable Patient: Rate vs Rhythm Control Redux

35 Heart Rate Control Believed to be associated with improved symptoms, better functional status and reduced chance of tachycardia mediated cardiomyopathy Belief is extrapololated from epidemiological data suggesting that faster heart rates in NSR associated with increased mortality Current guidelines (little evidence underpinning) Resting HR <80 BPM Exercise induced HR <110 BPM

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37 Strict control N=303 Lenient control N=311 % meeting target HR Total # of OP visits 67.0% 97.7% Mortality (%) Min F/U 2 years, Max F/U 3 years Primary Endpoint: CV death/chf hospitalization/cva/te/bleeding/life threatening arrhythmias Van den Berg et al. NEJM 2010

38 Should we leave PAF alone? Insights from CARAF Overall rate of paroxysmal or chronic AF at 5 years: 63.2% Overall rate of chronic AF at 5 years: 24.7% Kerr et al. Am Heart J. 2005; 149:

39 The Conventional Wisdom: AFFIRM No mortality benefit from an aggressive rhythm control strategy AFFIRM Investigators. NEJM 2002; 347:

40 Nuances of AFFIRM Mean age of patients was 70 years of age Majority of patients had either hypertension (51%) or CAD (26%); only 12% of patients had no history of cardiovascular disease This population is known to have increased risk of proarrhythmia from currently available antiarrhythmic drugs (AAD) Rhythm control strategy associated with improvement in functional status

41 Classes of available antiarrhythmic drugs and site of action Class Ia Disopyramide Procainamide Class Ib Quinidine Lidocaine Mexilitine CLASS IV Class Ic Flecainide Propafenone CLASS III Class II Class III eg propranolol Amiodarone Bretylium Dofetilide Ibutilide CLASS I CLASS II Sotalol Class IV non dihydropyridine calcium channel blockers eg verapamil and diltiazem ACC/AHA/ESC 2006 guidelines. J Am Coll Cardiol 2006;48:

42 CTAF: Modest effect of previously available AAD Intention to treat All patients 1 in 5 patients intolerant of amiodarone Intention to treat All patients in NSR at start of trial Roy et al. NEJM 2000; 342:

43 ATHENA: Primary Endpoint: CV Hospitalization or Death Cumulative Incidence (%) Placebo on top of standard therapy* DR 400mg bid on top of standard therapy* HR=0.76 p< Months Patients at risk: Placebo DR2400mg2bid * Standard therapy may have included rate control agents (beta-blockers, and/or Ca-antagonist and/or digoxin) and/or anti-thrombotic therapy (Vit. K antagonists and /or aspirin and other antiplatelets therapy) and/or other cardiovascular agents such as ACEIs/ARBs and statins. Mean follow-up 21 ±5 months. Hohnloser SH et al. N Engl J Med 2009;360:

44 COUNTERPOINT: PALLAS Connolly et al NEJM :

45 Pulmonary Vein Encircling and Ablation Can be highly effective in selected pts: symptomatic AF low AF burden Normal heart Overall success ~70-80%

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47 Functional status in atrial fibrillation: impact of disease and treatment Dorian et al. Can J Cardiol 2006; 22:

48 CCS Recommendations for a Rhythm Control Strategy Gillis et al. Can J Cardiol 2011; 27: 47-59