Lecture 7

Question 1

definition of afib

Answer 1

Abnormal tachyarrhythmia characterized by rapid and irregular beating

Question 2

pathophysiology of afib

Answer 2

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

Question 3

signs and symptoms of afib

Answer 3

SSx

• absent in 1/3 of patients
• Palpitations
• Tachycardia (irregular)
• DOE (rapid ventricular response)
• Fatigue
• Lightheadedness

Question 4

definitive diagnosis of afib

Answer 4

EKG- absence of P waves, fast/ irregular

Question 5

paroxysmal AF

Answer 5

-most common subtype (50%) -terminates by itself within 7 days of onset (most within 24 hrs)

Question 6

persistent AF

Answer 6

-doesnt self terminate or lasts longer than 7 days

Question 7

permanent AF

Answer 7

longstanding AF, usually persisting for more than 1 year despite treatment

Question 8

lone AF

Answer 8

-AF arising in a structurally normal heart without a precipitant

Question 9

acute AF

Answer 9

-any subtype of AF within the first 24 hrs of onset, be it persistent, permanent or paroxysmal

Question 10

risk factors for AF

Answer 10

• 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”

Question 11

AF and stroke risk

Answer 11

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)

Question 12

treatment of AF

Answer 12

Primary Goals:

1) Prevent embolic stroke through anticoagulation
2) Prevent cardiac damage through heart rate control
3) Back to normal when necessary

Question 13

assessment of stroke risk

Answer 13

1) CHADS2VASC Score (most validated)
2) LV function / LA size & function (cardiology)

Question 14

assessment of bleeding risk

Answer 14

1) HASBLEED 2) HEMORR2HAGES

Question 15

CHADS2VASc score

Answer 15

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)

Question 16

Anticoagulation guidelines

Answer 16

Question 17

HAS-BLED

Answer 17

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)

Question 18

goals of anticoagulation

Answer 18

To prevent embolic stroke by reducing thrombus burden in the heart LAA

NOTE: serious bleeding risk & must be used carefully!

Question 19

VKA - warfarin

Answer 19

(standard of care) - Titrated to an INR 2-3

PROS: cheap

CONS: Blood tests, DDIs, food interactions (vitamin K), reversal is not that simple!

Question 20

Xa inhibitors and IIa inhibitors: benefits and contraindication

Answer 20

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

Question 21

Factor Xa inhibitors

Answer 21

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

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Question 22

Direct thrombin (IIa) inhibitor

Answer 22

Pradaxa (dabigatran) – Re-ly Study (CHADS2 2.1)

75, 150 mg BID

Superior for ischemic CVA prevention

High risk of GI bleeding

Dyspepsia

Question 23

RACE and AFFIRM trials

Answer 23

Rate control strategy NOT inferior to rhythm control in pts w/ persistent AF w/ regard to morbidity, mortality & QOL

1. Target average heart rate
   - lenient (RHR <110bmp) vs. strict (<80bpm)
2. Titrate meds to lower rate based on symptoms (70-90 bpm)
3. Difficulty of preventing rapid ventricular response (RVR) with exertion

Question 24

Rate control

Answer 24

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

Question 25

When do we have to attempt rhythm conversion?

Answer 25

1) Unstable patient in emergent setting 2) When comorbidities destabilize a patient ex: HF, CAD patient with unstable angina

Question 26

when should we consider rhythm control?

Answer 26

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

Question 27

rhythm conversion

Answer 27

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

Question 28

antiarrhythmics

Answer 28

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

Question 29

radiofrequency ablation

Answer 29

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

Question 30

Surgical/procedural reduction of AF/CVA risk

Answer 30

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

Question 31

atrial flutter

Answer 31

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%)

Question 32

afib algorithm

Answer 32

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)