Post on 31-Dec-2015
Embed Size (px)
DESCRIPTIONAtrial Fibrillation. BGSMC Cardiology Study Group January 6, 2011 Mohamad Lazkani, MD Tomas Rivera-Bonilla, MD Nick Sparacino, DO. Introduction. History William Harvey *1628 Robert Adams reported *1827 Etienne Marey *1863 Sir Thomas Lewis *1909 Bootsma and coworkers *1970 - PowerPoint PPT Presentation
Atrial FibrillationBGSMC Cardiology Study GroupJanuary 6, 2011
Mohamad Lazkani, MDTomas Rivera-Bonilla, MDNick Sparacino, DO
IntroductionHistory William Harvey *1628 Robert Adams reported *1827 Etienne Marey *1863 Sir Thomas Lewis *1909 Bootsma and coworkers *1970 William Kannell and colleagues *1982
EpidemiologyMost common dysrrhythmiaOverall lifetime risk ~25%416,000 hospital discharges in 2001Avg medicare cost of hospitalization 6k, not including followup, procedures (echo, etc), meds50-90% increase in mortality from Framingham study
Recognizing A FibClassic irregularly irregular pulseRemember to take pulse at carotids, not peripherallyEKG WITHOUT P WAVESNote all that is irregular is not a fib
Classification of Atrial FibrillationPresence of other cardiac diseaseLone atrial fibrillationValvular atrial fibrillationType of presentationFirst detected episode RecurrentPersistenceParoxysmal self converts within 7 daysPersistent requires pharmacologic or electrical cardioversion, but does convertPermanent refractory to attempts
CausesValvular diseaseMS is classic, but any state that can cause dilation of the atria aka any valvular issueHypertension Most common in USAlcohol holiday heartMIFamilial Mutation in slow K channel causes increased inward K flux and decreased refractory periodHyperthyroidHypersympathetic statesPost-operative
Pathophysiology - Initiation
Pulmonary vein muscle sleeves
2)Epicardially contiguous with myocardium of atria3)Less commonly in the similarly arranged muscular sleeves of the proximal SVC
Pathophysiology - Perpetuation2 Preconditions for reentryHeterogeneous conductionAllows preferential unidirectional conductionAllows impulse to still be traveling down slow path while fast path is repolarizingShort refractory periodAllows fast path to be primed for depolarization by the time the slow pathway reaches previously depolarized fast tissue
Mechanism of ConductionThe AV node limits conduction during AF.
There appear to be 2 distinct atrial inputs to the AV node, posteriorly via the crista terminalis and anteriorly via the interatrial septum.
Remodeling A fib begets A fib2 MechanismsDecrease in fast Na channel and L-type Ca channel expression = Short Refractory PeriodIncreased metabolic and mechanical stress leads to reparative and reactive fibrosis = Heterogenous ConductionHmm Short refractory period and heterogeneous conduction, that sounds familiar
ConsequencesDecrease in Cardiac Output
Why treat Atrial Fibrillation?One of every 6 strokes occurs in patients with AF. The overall risk of thromboembolism is approximately 5% per yearIn the Framingham cohort, (OR) for total mortality was 1.5 for men and 1.9 for women with AF after the analysis was adjusted for age, overt heart disease, and other risk factors Rheumatic heart disease and AF had a 17-fold increased risk of stroke. The AR* on rheumatic heart disease was 5 times greater than in those with nonrheumatic AF
Loss of synchronous atrial mechanical activity Irregularity of ventricular response Inappropriately rapid heart rate
Management of Atrial FibrillationThe dilemma as to whether to try rhythm control, or to accept the arrhythmia and control the ventricular rate
Rate control strategies : symptomatic improvement is achieved solely because of better control of the ventricular rate
Rhythm control strategies: It has been demonstrated that restoration of sinus rhythm is associated with improvements in exercise capacity and peak oxygen consumption, both in patients with structural heart disease and in those with normal hearts. However, drugs used for rhythm control may cause serious proarrhythmia.
Dilemma of Rate vs Rhythm
Pharmacological Agents for Rate and Rhythm Control
Nonpharmacological Approach for AFIBSurgical AblationCatheter AblationSuppression of AF by PacingInternal Atrial Cardioverter/ DefibrillatorsThe Radiofrequency Ablation for Atrial Fibrillation Trial (RAAFT), will better assess the late recurrence rates of AF. The effect of ablation on mortality rates, quality of life, and health care costs will probably be better established during the coming years.The CABANA (Ablation vs Drug Therapy for Atrial Fibrillation) pilot study, will be followed by a 3000-patient CABANA mortality trial, in which 1500 patients older than 65 years or younger than 65 years but with other risk factors for stroke will be randomly assigned to drug therapy, and an additional 1500 such patients will be randomly assigned to ablative intervention.
Anticoagulation TherapyCHADS score Gender (female sex) Mitral StenosisDilemma: ACC/AHA/ESC AF Guidelines. Six randomized trials have compared adjusted-dose warfarin to placebo reduction in stroke averaged about 60% Six randomized trials comparing aspirin to placebo show a small effect of aspirin, averaging about 20% for reduction in all stroke
New Anticoagulation OptionAnticoagulation:RELY [Randomized Evaluation of Long-term anticoagulant therapY] trialDabigatran is a competitive, and reversible inhibitor of thrombin, inhibiting both thrombin activity and generationpeak plasma concentrations of dabigatran are reached approximately 2 hours after oral administration.
Dabigatran is not metabolized by cytochrome P450 isoenzymes, has no interactions with food, and also has a low potential for drugdrug interactions The elimination half-life is 12 to 14 hours, with clearance predominantly occurring via renal excretion of unchanged drug.
New medication for rhythm controlATHENA (A Trial With Dronedarone to Prevent Hospitalization or Death in Patients With Atrial Fibrillation) trial Indirect meta-analysis by Piccini et al. Compared amiodarone with dronedarone in AF.Patients treated with amiodarone, compared with dronedarone, were twice as likely to remain in sinus rhythm
However, amiodarone was associated with a trend toward greater all-cause mortality and was associated with greater rates of adverse events requiring drug discontinuation.
Analytical approach to compare 2 drugs that have not been studied in a head-to-head randomized controlled trial
New medication for rhythm control
Question 1A previously healthy 47-year-old woman presented 6 days ago with a complaint of palpitations of sudden onset. Her evaluation at that time included an electrocardiogram, which revealed atrial fibrillation (AF) with a ventricular response of 135 beats/min. She was late for an interview, and unfortunately she left the office before you were able to evaluate her. Her symptoms persisted without resolution until yesterday. She decided to return to your office out of fear of this happening again. Repeat EKG shows normal sinus rhythm. Her cardiac examination is unremarkable. She has no other medical problems and takes no medications. A transthoracic echocardiogram (TTE) is normal. Which of the following is the most likely classification of this patient's AF?
A. Permanent B. Persistent C. Recurrent D. Isolated E. Paroxysmal
Question 1 Key Concept/Objective:To understand the appropriate classification of AFAnswer: EThe ACC/AHA/ESC guidelines include the following categories: recurrentmore than one episode of AF has occurred; lone AF occurring in a patient younger than 60 years who has no clinical or echocardiographic evidence of cardiopulmonary disease; valvularAF occurring in a patient with evidence or history of rheumatic mitral valve disease or prosthetic heart valves is defined as valvular; paroxysmalAF that typically lasts 7 days or less, with spontaneous conversion to sinus rhythm; persistentAF that typically lasts longer than 7 days or requires pharmacologic or direct current (DC) cardioversion; permanentAF that is refractory to cardioversion or that has persisted for longer than 1 year. Paroxysmal, persistent, and permanent AF categories do not apply to episodes of AF lasting 30 seconds or less or to episodes precipitated by a reversible medical condition. Reversible conditions include acute myocardial infarction, cardiac surgery, pericarditis, myocarditis, hyperthyroidism, pulmonary embolism, and acute pulmonary disease.
Question 2A 75-year-old woman with a history of symptomatic, recurrent, persistent nonvalvular AF comes to your office. She has been told that there are several options for the treatment of her AF. Which of the following is true regarding establishment and maintenance of normal sinus rhythm, as compared with pharmacologic rate control?
A. Establishment and maintenance of sinus rhythm provides no survival advantage B. Establishment and maintenance of sinus rhythm reduces thromboembolic risk C. Establishment and maintenance of sinus rhythm improves the degree of symptomatic impairment D. Conversion to normal sinus rhythm is rarely needed for patients with unstable angina, acute myocardial infarction, heart failure, or pulmonary edema E. Answer choices B, C, and D are all true
Question 2 Key Concept/Objective:To understand that establishment and maintenance of sinus rhythm is not superior to ventricular rate control in patients with AFAnswer: ASeveral trials compared restoration of sinus rhythm with control of ventricular rate in patients with AF. Evaluated outcomes included overall mortality, stroke, symptoms, and quality of life. Contrary to the expectations of many experts, maintenance of sinus rhythm provided no survival advantage and possibly a higher mortality when compared with ventricular rate control. Maintenanc