Info
🌱 來自: Huppert’s Notes
Irregular Atrial Rhythms🚧 施工中
Irregular Atrial Rhythms
Premature atrial complexes (PACs)
• Description: Most common cause of irregular pulse and palpitations; benign, increased frequency with age, illness, tobacco/alcohol/caffeine
• ECG: Extra P waves, often with different morphology, and can be followed by a pause
• Treatment: None required unless symptomatic
Multifocal atrial tachycardia (MAT)
• Description: Increased automaticity at multiple sites in the atria. Associated with COPD, HF, hypokalemia, hypomagnesemia.
• ECG: ≥3 P waves with differing morphologies, atrial rates usually 100–130 bpm
• Treatment: CCB or BB if tolerated; treat underlying disease process
Atrial flutter with variable block
• Description: Atrial flutter with alternating block (e.g., 2:1 then 3:1). See Atrial flutter on prior page.
Atrial fibrillation (Afib)
• Description: Low-amplitude atrial activity that often originates in the pulmonary veins and oscillates at a rate of ~300–600 bpm; atrial activity is transmitted irregularly through the AV node, resulting in an irregular (often fast) ventricular rate
• Predisposing factors: Heart disease (e.g., CAD, MI, HTN, valve), older age, obesity, OSA
• Episodic/reversible triggers: Infection, heart surgery, VTE/PE, hyperthyroidism, alcohol, stress
• Symptoms: Fatigue, dyspnea, palpitations, irregular pulse, thrombi, stroke
• ECG: Irregularly irregular ventricular rhythm (e.g., irregular RR intervals, tiny erratic spikes), no P waves (Figure 1.14)
• Workup of new Afib: TSH, BMP, LFTs, TTE; calculate CHA2DS2-VASc and HAS-BLED scores (online calculators) to help determine need for anticoagulation, ambulatory ECG monitor (assess rate control), +/– sleep study
• Classifications:
- Paroxysmal (<7 days) vs. persistent (>7 days) vs. long-standing persistent (>1 yr) vs. permanent (refractory to cardioversion)
- Valvular vs. nonvalvular
- Lone Afib (age <60 yr, without hypertension or structural heart disease)
- Symptomatic (~75%) vs. asymptomatic (~25%)
• Treatment of Afib with rapid ventricular response (RVR):
- Assess patient stability: Heart rate, blood pressure, mental status
• UNSTABLE: Emergent synchronized cardioversion
• STABLE: Manage as follows:
- Identify and treat the triggering condition (e.g., infection, drugs, subarachnoid hemorrhage, medication noncompliance)
- Rate control: Options for rate control agents include the following, in order of preference:
• Beta blocker (careful in decompensated HF)
• Calcium channel blocker (contraindicated in HF)
• Amiodarone (also used for rhythm control so may result in cardioversion)
• Digoxin (longterm use associated with increased mortality)
- Consider cardioversion:
• Types: Pharmacological (amiodarone) or electrical (direct current cardioversion [DCCV])
• Obtain TEE before cardioversion in most patients, especially if not reliably anticoagulated for >4 weeks or Afib duration >48 hours (unless emergent)
• Contraindication to cardioversion: Presence of left heart thrombus
• Post-cardioversion: All patients require 4 weeks of anticoagulation due to increased stroke risk from cardiac stunning (although most will require lifelong anticoagulation due to an elevated CHA2DS2-VASc score)
• Treatment of chronic Afib:
- Treat reversible causes and triggers (e.g., OSA, obesity, hyperthyroidism, heart failure)
- Reduce stroke risk:
• Anticoagulation:
- Valvular Afib: e.g., Afib from mitral stenosis. Anticoagulate with warfarin (INR goal 2–3)
- Nonvalvular Afib: Anticoagulate if history of TIA/stroke or CHA2DS2-VASc ≥2 (~2% annual stroke risk). Consider for CHA2DS2-VASc score of 1 (<1% annual stroke risk). Reconsider anticoagulation if HAS-BLED ≥5 (≥12% annual major bleeding risk with warfarin). Choice of warfarin or direct oral anticoagulant (DOAC) (e.g., apixaban 5 mg BID, rivaroxaban 20 mg daily with food, or dabigatran 150 mg BID). If patient on DAPT for CAD and Afib, discontinue the second antiplatelet and only use dual therapy (RE-DUAL 2017).
- Post-op Afib: Patients with new Afib after cardiac surgery usually don’t need chronic anticoagulation; anticoagulate for 2–3 months, then discontinue if confirmed sinus on ambulatory ECG monitoring.
• Procedures:
- Left atrial appendage closure: Patients may be able to discontinue anticoagulation if success of closure confirmed by TEE; can be done surgically or percutaneously (WATCHMAN procedure).
- Manage the arryhthmia:
• Rate control:
- Rate control is noninferior to rhythm control in asymptomatic patients >65 yr (AFFIRM 2002), although rhythm control is still preferred for certain patients
- Types of rate control therapies:
• Medications: BB or CCB to achieve goal HR <110 bpm with activity (RACE II 2010)
• Procedures (less commonly used strategy): AV node ablation and pacemaker placement
• Rhythm control:
- Consider for:
• Symptomatic patients
• Young patients (generally recommend at least one DC cardioversion [DCCV] attempt)
• HFrEF (catheter ablation may have improved outcomes, CASTLE-AF 2018)
- Types of rhythm control therapies:
• Cardioversion:
- Indicated to restore sinus rhythm at least once in patients with persistent Afib who are <65 yr or ≥65 yr and symptomatic despite rate control
- Duration of sustained sinus rhythm following cardioversion is variable, and early reversion to Afib occurs frequently in patients with a history of long-standing persistent Afib or LA diameter >5 cm
• Antiarrhythmic drugs:
- Scheduled medications: Goal to suppress Afib episodes tô1×/year; rarely completely eliminates Afib. Options: Class IA (quinidine, procainamide), class IC (flecainide, propafenone), class III (sotalol, dofetilide); amiodarone (used for select patients given long-term side effects)
- PRN dosing: Flecainide or propafenone “pill-in-pocket” strategy; appropriate in paroxysmal symptomatic Afib with CHA2DS2-VASc 0 in “lone Afib”
• Procedures:
- Cryoballoon ablation: Percutaneous; circumferential ablation around the pulmonary vein (PV) antrum for PV isolation; risk of phrenic nerve injury and PV stenosis; typically requires less technical skill and time than radiofrequency ablation
- Radiofrequency catheter ablation: Percutaneous; mapping with directed ablation for PV isolation; similar efficacy to cryoballoon with possibly fewer complications
- MAZE procedure: Surgical; intraoperative ablation to isolate PVs, most often performed in patients getting cardiac surgery for another indication or those who failed catheter ablation
TABLE 1.10 • Indications for Implantable Cardioverter Defibrillators (ICDs)