Clinical Quick Reference — Pacing, ICD, and CRT Management
Published: Journal of the American College of Cardiology (2013) Societies: ACCF / AHA / HRS (focused update of 2008 guidelines) DOI:10.1016/j.jacc.2012.11.007
This focused update incorporates pivotal trials and new evidence. Key changes:
Major Updates
CRT Expansion: Class I for LVEF ≤35%, sinus rhythm, LBBB ≥150 ms, NYHA II–IV
ICD Primary Prevention: Refined LVEF thresholds (≥40 days post-MI, ≤30% for non-ischemic)
Remote Monitoring: NEW section on transtelephonic and wireless remote monitoring
Pediatric ICDs: Expanded coverage for genetic conditions and congenital heart disease
Pacing for Sinus Node Dysfunction
SND presents with bradycardia, bradycardia-tachycardia syndrome, or chronotropic incompetence. Treatment is indicated for symptomatic patients.
Class I: Permanent Pacing Indicated
Indication
Details
COR
Symptomatic bradycardia
Documented symptomatic bradycardia with pauses ≥3 seconds or sinus rate <40 bpm with clear symptom correlation
1
Chronotropic incompetence
Symptomatic inability to achieve adequate HR with exertion
1
Symptomatic bradycardia + required drug therapy
Bradycardia due to essential cardiac medications (beta-blockers, rate-limiting CCBs)
1
Class II & III
Class IIb: SND with HR 40–50 bpm if clear symptom-rhythm correlation. Class III: Asymptomatic SND.
Pearl: Always correlate symptoms with bradycardia. Use Holter or event monitoring if correlation is unclear. Asymptomatic SND does not require pacing.
Pacing for Atrioventricular Block
Management depends on degree, location (AV nodal vs. infra-Hisian), and symptom status.
First-Degree AV Block
No Pacing
Not indicated even if symptomatic. Class III.
Second-Degree Type I (Wenckebach)
Generally Not Indicated
Benign prognosis; pacing not recommended unless symptomatic at infra-Hisian level. Class III.
Second-Degree Type II & Advanced 2nd Degree
Pacing Indicated
Type II symptomatic: Pacing indicated for symptoms (syncope, dyspnea). Class I.
Asymptomatic infra-Hisian: Pacing indicated even without symptoms if proven infra-Hisian block. Class I.
Advanced 2nd-degree: Pacing indicated at any site. Class I.
Third-Degree AV Block
Pacing Clearly Indicated
Persistent 3rd-degree post-MI: Permanent ventricular pacing. Class I.
Transient infra-Hisian block + bundle-branch block: Permanent pacing. Class I.
Chronic 3rd-degree with wide QRS (infra-Hisian): Pacing indicated regardless of symptoms. Class I.
AV Block Decision Tree
Step 1: Narrow QRS (AV nodal) or wide QRS (infra-Hisian)?
Narrow QRS: May trial drugs before pacing. Wide QRS: Pacing generally indicated.
Step 2: Are symptoms present (syncope, dyspnea)?
YES → Pacing indicated (Class I)
NO but structural disease → Pacing reasonable (Class IIa)
Pearl: Infra-Hisian block (wide QRS, HV >100 ms) carries high risk of sudden progression and merits pacing even if asymptomatic. Use EPS if site is unclear.
Pacing for Special Conditions
Cardiac Transplantation
Class I: Permanent pacing is indicated for persistent bradycardia not expected to resolve. Class I, LOE: C.
Hypertrophic Cardiomyopathy (HCM)
Class IIa: Permanent pacing may be considered for medically refractory LVOT obstruction with symptoms. Class IIa, LOE: A.
Neuromuscular Diseases
Key Point: Progressive AV block is common in myotonic dystrophy and Emery-Dreifuss dystrophy. Anticipate need for pacing and follow closely.
Sleep Apnea
Note: Pacing does NOT treat sleep apnea. PAP therapy is first-line. Patients with OSA and symptomatic bradycardia may benefit from pacemaker therapy.
Cardiac Resynchronization Therapy (CRT)
CRT is indicated for LVEF ≤35%, QRS ≥120 ms (preferably LBBB), and NYHA II–IV symptoms on optimal medical therapy. Available as CRT-P (pacemaker) or CRT-D (defibrillator).
Primary prevention ICDs reduce SCD mortality in high-risk patients without prior ventricular arrhythmias. LVEF ≤35% is the cornerstone criterion.
Class I: ICD Clearly Indicated
Definite Indications
Prior cardiac arrest (VF/VT): After reversible causes excluded. LOE: A
Structural disease + spontaneous sustained VT: LOE: B
Ischemic cardiomyopathy: LVEF ≤30%, prior MI ≥40 days, NSVT on Holter, inducible VT on EPS (MADIT II criteria). LOE: A
Nonischemic DCM: LVEF ≤35%, NYHA II–III (SCD-HeFT). LOE: B
Class IIa: ICD Reasonable
Indication
LOE
COR
Unexplained syncope, reduced LVEF, inducible VT: ICD reasonable. LOE: C
C
2a
Sustained VT, normal or near-normal EF: ICD reasonable. LOE: B
B
2a
HCM with ≥1 major SCD risk factor: ICD reasonable (unexplained syncope, family hx SCD, LVOT gradient, wall thickness ≥30 mm). LOE: C
C
2a
ARVC with risk factors: ICD reasonable (unexplained syncope, NSVT, family hx SCD, extensive RV involvement). LOE: C
C
2a
Class IIb: May Be Considered
Nonischemic DCM, LVEF ≤35%, NYHA Class I: LOE: C
Long-QT syndrome, high-risk, recurrent syncope: LOE: B
Brugada syndrome with high-risk features: LOE: C
CPVT with syncope despite beta-blockers: LOE: C
Key Takeaway: LVEF ≤35% (≤30% in some populations) at least 40 days post-MI or in non-ischemic cardiomyopathy is the main driver for primary prevention ICD. → Use MADIT Risk Calculator
ICD — Secondary Prevention
Secondary prevention ICDs are indicated for survivors of cardiac arrest or sustained VT with structural disease.
Class I: ICD Clearly Indicated
Definite Indications
Cardiac arrest from VF or hemodynamically unstable VT: After reversible causes excluded. LOE: A
Structural disease + spontaneous sustained VT: Whether hemodynamically stable or unstable. LOE: B
Syncope of undetermined origin + inducible VT: With structural disease present. LOE: C
Specific Disease States
Condition
ICD Recommendation
COR
CAD with prior MI + sustained VT/VF
Class I indicated
1
Nonischemic DCM + VT/VF, LVEF <35%
Class I indicated
1
Long-QT + recurrent syncope despite BBs
Class IIa reasonable
2a
Brugada syndrome + documented VT/VF or high-risk
Class IIa reasonable
2a
CPVT + recurrent syncope despite BBs
Class IIb may be considered
2b
Key Takeaway: All cardiac arrest survivors from VT/VF (barring reversible cause) or patients with sustained VT and structural disease should receive an ICD.
Device Selection and Lead Management
Pacemaker Type Selection
Device
Indication
Key Advantage
Single-chamber atrial
SND without AV block; preserve AV synchrony
Lower cost; simpler; maintains AV conduction
Single-chamber ventricular
Chronic AF; VVI pacing appropriate
Appropriate for AF; rate response available
Dual-chamber
AV block; SND with need for AV sync; improve hemodynamics
Maintains AV synchrony; better QOL; reduces AF risk
Lead Longevity: Modern leads function 10–15+ years. Lead extraction may be needed for infection, failure, recall, or vascular obstruction. Always balance extraction risk against risk of leaving a failed lead.
Indications for Lead Extraction
Device infection or endocarditis
Lead fracture or insulation failure with loss of function
Lead recall or safety advisory
Vascular access obstruction preventing new lead placement
Transvenous lead system dysfunction requiring revision
Pacemaker and ICD Follow-Up
Routine follow-up ensures early detection of battery depletion, lead problems, and appropriate device function.
Follow-Up Schedule
Device
Interval
Frequency
Pacemaker (single/dual-chamber)
1st month post-implant
Every 2 weeks
2nd–36th month
Every 8 weeks
37th month–battery failure
Every 4 weeks
ICD
1st month post-implant
Every 2 weeks
2nd–6th month
Every 4 weeks
7th–36th month
Every 8 weeks
37th month–battery failure
Every 4 weeks
Remote Monitoring (2012 Update)
Transtelephonic Monitoring (TTM) & Wireless Remote Monitoring: Increasingly used to supplement in-office visits. Allows remote interrogation of rhythm, pacing thresholds, battery, lead integrity, and early detection of clinically actionable events (AF, arrhythmias, lead failures). Hybrid approaches (remote + select office visits) improve safety and convenience without compromising clinical outcomes.
Assessment at Each Visit
Required Elements
Patient clinical status and device tolerance
ECG with capture, sensing, AV intervals documented
Patient education and counseling on device restrictions (driving, MRI, security, etc.)
Special Populations
Elderly Patients
Key Point: Age is not a contraindication. However, in elderly with multiple comorbidities, balance procedural risk and longevity against device benefit. Shared decision-making is essential.
Congenital Heart Disease
Pediatric Populations: ICD indications similar to adults, but threshold for intervention may be lower due to long life expectancy. SCD prevention is particularly important in young patients.
Heart Transplant Candidates
Device Use in Transplantation
ICDs can bridge to transplantation in SCD-at-risk patients awaiting donor organs
Mechanical circulatory support (VAD) increasingly used as destination therapy or bridge
Some post-transplant patients develop SND or AV block requiring pacemaker
Pregnancy
Pregnancy with Device Therapy: Women can safely become pregnant. Requires coordination between obstetrics, cardiology, and EP. Optimize device settings and monitor closely for arrhythmias. Remote monitoring is particularly valuable.
Neuromuscular & Genetic Diseases
Progressive Conduction Disease: Myotonic dystrophy, Emery-Dreifuss, and related conditions have high risk of progressive AV block. Anticipate early device need and follow closely.
Sleep Apnea
Note: Pacing does NOT treat sleep apnea. PAP therapy is first-line. Patients with OSA + symptomatic bradycardia may benefit from pacemaker therapy.
Related Calculators
Use these SattiMD calculators to support device therapy decision-making: