Lecture 7 Flashcards
definition of afib
Abnormal tachyarrhythmia characterized by rapid and irregular beating
pathophysiology of afib
1) Dilation from rise in intra-atrial pressure leads to activation of RAAS and ultimately atrial remodeling & fibrosis
2) Disorganized electrical impulses develop usually originating from pulmonary veins
3) Left atrial squeeze is diminished, LA appendage is stunned
signs and symptoms of afib
SSx
- absent in 1/3 of patients
- Palpitations
- Tachycardia (irregular)
- DOE (rapid ventricular response)
- Fatigue
- Lightheadedness
definitive diagnosis of afib
EKG- absence of P waves, fast/ irregular
paroxysmal AF
-most common subtype (50%) -terminates by itself within 7 days of onset (most within 24 hrs)
persistent AF
-doesnt self terminate or lasts longer than 7 days
permanent AF
longstanding AF, usually persisting for more than 1 year despite treatment
lone AF
-AF arising in a structurally normal heart without a precipitant
acute AF
-any subtype of AF within the first 24 hrs of onset, be it persistent, permanent or paroxysmal
risk factors for AF
- Obstructive Sleep Apnea
- Obesity
- Long standing HTN / CHF/Ischemic Heart Dz
- Valvular Heart Disease -especially L-sided (mitral regurgitation and mitral stenosis)
- Cardiac surgery
- Hyperthyroidism
- Genetic predisposition
- Dehydrating factors: Viral illness, colonoscopy prep, cancer (chemotherapy), Alcohol- binge drinking “holiday heart”
AF and stroke risk
4-5x inc risk of stroke
3x inc risk of heart failure
2x inc risk of dementia
50% inc risk of death in men, nearly 100% in women
AF strokes more disabling and more often fatal, more likely to recur
Pathology: Thrombus formation in the left atrial appendage (LAA)
treatment of AF
Primary Goals:
1) Prevent embolic stroke through anticoagulation
2) Prevent cardiac damage through heart rate control
3) Back to normal when necessary
assessment of stroke risk
1) CHADS2VASC Score (most validated)
2) LV function / LA size & function (cardiology)
assessment of bleeding risk
1) HASBLEED 2) HEMORR2HAGES
CHADS2VASc score
C - CHF (1)
H - HTN (>140/90) (1)
A - Age >/= 75 (2)
D - Diabetes mellitus (1)
S2 - prior TIA or stroke (2)
V - vascular disease (MI, aortic plaque, etc.) (1)
A - Age 65-74 (1)
Sc - Sex category (female = 1)
Anticoagulation guidelines
HAS-BLED
H - hypertension (1)
A - abnormal liver or renal function (1 or 2)
S - stroke (1)
B - bleeding (1)
L - Labile INR (1)
E - elderly (age >65) (1)
D - drugs or alcohol (1 or 2)
goals of anticoagulation
To prevent embolic stroke by reducing thrombus burden in the heart LAA
NOTE: serious bleeding risk & must be used carefully!
VKA - warfarin
(standard of care) - Titrated to an INR 2-3
PROS: cheap
CONS: Blood tests, DDIs, food interactions (vitamin K), reversal is not that simple!
Xa inhibitors and IIa inhibitors: benefits and contraindication
Benefits:
1) NO blood testing
2) NO food interaction (Vitamin K does not affect)
3) Less drug interactions
4) Safer bleeding profile (all have less ICH than Warfarin)
CONTRAINDICATIONS:
-mechanical valve replacement / severe mitral stenosis / ESRD
Factor Xa inhibitors
1) Xarelto (rivaroxaban) – ROCKET-AF (CHADS2- 3.5)
15, 20 mg once daily with dinner
Non-inferior to VKA
2) Eliquis (apixaban) – ARISTOTLE (CHADS2 2.1)
2. 5, 5 mg twice daily
Low risk of bleeding
Mortality benefit
3) Savaysa (edoxaban)- ENGAGE AF (CHADS2 2.8)
30, 60 mg once daily
¡
Direct thrombin (IIa) inhibitor
Pradaxa (dabigatran) – Re-ly Study (CHADS2 2.1)
75, 150 mg BID
Superior for ischemic CVA prevention
High risk of GI bleeding
Dyspepsia
RACE and AFFIRM trials
Rate control strategy NOT inferior to rhythm control in pts w/ persistent AF w/ regard to morbidity, mortality & QOL
- Target average heart rate
- lenient (RHR <110bmp) vs. strict (<80bpm) - Titrate meds to lower rate based on symptoms (70-90 bpm)
- Difficulty of preventing rapid ventricular response (RVR) with exertion
Rate control
1)Beta-Blockers – Most effective class!
Cardioselective- Bisoprolol, Metoprolol, Carvedilol, Nebivolol
2) Non-Dihydropyridine CCBs (aka cardio-selective)
Diltiazem, Verapamil
3) Digoxin – may add synergistic rate control w/ above meds
No effect on BP (CHF patients)
4) Pacemaker + AV Nodal Ablation
Last resort
When do we have to attempt rhythm conversion?
1) Unstable patient in emergent setting
2) When comorbidities destabilize a patient
ex: HF, CAD patient with unstable angina
when should we consider rhythm control?
1) Symptomatic AF despite good rate control
2) Difficult to control rate
3) pts who developed tachycardia-mediated cardiomyopathy
2) Younger active patient
3) Small left atrial size
rhythm conversion
1) Electrical Cardioversion w/TEE- echocardiogram of heart with a probe placed in the esophagus (great view of LAA)
2) Chemical Cardioversion - Anti-arrhythmic Rx – select carefully
- consider underlying cardiac dz & comorbidities
- consider pro-arrhythmic & toxic potential
3) Transvenous catheter ablation – radiofrequency & cryotherapy on pulmonary veins
antiarrhythmics
Outpatient
Onset unknown- patient must be anticoagulated for at least 4 weeks
Onset known- within 48 hours no TEE needed
Most common agent is Amiodarone
1) High success of conversion back to sinus rhythm
2) Safe for all types of patients in terms of EF / valvular issues
3) Short term use only due to toxicity – thyroid, liver, lung
radiofrequency ablation
Procedure
1) Percutaneous, radiofrequency catheter (cryo or heat)
2) Disrupts the propagation of electrical current
3) Pulmonary vein isolation (PVI) or wide area circumferential ablation (WACA)
4) Difficult procedure (60-70% success on first attempt)
5) More medications before and after procedure
6) Anticoagulation may be needed for extended period
Surgical/procedural reduction of AF/CVA risk
1) Surgical MAZE
Incisions that are sewn together to disrupt re-entry currents (oldest)
2) LA Appendage Ligation / Closure
a) Surgical ligation / closure
b) WATCHMAN device – seals opening (cath based) (1:26)
c) LARIAT procedure- lasso close LAA through chest w/ guidewire system
atrial flutter
1) Supraventricular re-entry tachycardia (“saw-tooth pattern”, fast regular)
2) Treated similar to AF
Anticoagulation, rate control
3) Rhythm control
Consider early cardioversion, does not respond well to meds
4) Atrial flutter Ablation
Technically much easier than AF
High success rate (~97%)
afib algorithm
1) Anticoagulation (CHADS2VASC vs bleeding risk)?
2) Rate control (less than 110 bpm to prevent heart damage, push lower if still symptomatic)
3) Consider rhythm conversion based on continued symptomatic AF despite adequate rate control or confounding comorbidities (CHF, CAD)
