All clinical scenarios in this guideline are rated on a 9-point Likert scale by an independent rating panel. The final score determines appropriateness classification:
Appropriate (A)
Median score: 7–9 Device implantation is reasonable. Evidence and clinical judgment support the procedure.
May Be Appropriate (M)
Median score: 4–6 Device implantation may be reasonable. Benefits outweigh risks, but evidence is limited or variable.
Rarely Appropriate (R)
Median score: 1–3 Device implantation is rarely appropriate. Lacks clear evidence of benefit or clinical judgment deems unreasonable.
Key Principle: The AUC rating guides clinical decision-making but does not replace judgment. Individual patient circumstances, shared decision-making, and gaps in evidence should inform final recommendations.
Secondary Prevention: ICD for Survived Arrhythmias
CAD with Hemodynamically Unstable or Sustained VT/VF/PMVT
ICD implantation is appropriate for patients with coronary artery disease who have survived an episode of ventricular arrhythmia. Timing post-MI, LVEF, and revascularization status determine appropriateness.
Clinical Scenario
Timing Post-MI
AUC Rating
Single episode VF or polymorphic VT (≤48 hrs, newly diagnosed)
Acute (<48 hrs)
R
Recurrent VF/polymorphic VT despite medical therapy
Acute (<48 hrs)
M
Sustained monomorphic VT (≤48 hrs post-MI)
Acute (<48 hrs)
M
VF/polymorphic VT after revascularization, LVEF ≥35%
3–40 days post-MI
M
All VF/VT scenarios when LVEF <35%
>3 months (chronic)
A
Nonischemic Cardiomyopathy with Sustained VT/VF
Clinical Scenario
AUC Rating
Nonischemic dilated CM, sustained VT, LVEF ≤35%
A
Sarcoid heart disease with sustained VT/VF
A
Chagas disease with sustained VT/VF
A
Primary Prevention: ICD for SCD Risk Reduction
Primary prevention ICDs are indicated for high-risk patients without prior sustained arrhythmias. LVEF, NYHA functional class, and timing post-MI are critical determinants.
Post-Acute MI (≥40 Days): Ischemic Cardiomyopathy
Clinical Scenario
LVEF 30–40%
LVEF <30%
NYHA Class I, no NSVT
M
—
NYHA Class I, with NSVT
A
—
NYHA Class I–II, optimized GDMT
—
A
NYHA Class III–IV, GDMT <3 months
M
M
Nonischemic Cardiomyopathy: GDMT Timing
In newly diagnosed nonischemic CM, ICD is deferred until after ≥3 months optimization of medical therapy.
CRT is indicated for symptomatic HF with reduced LVEF and electrical dyssynchrony (wide QRS). Appropriateness varies by LVEF, NYHA class, QRS duration, LBBB, and etiology.
CRT: Ischemic Cardiomyopathy
LVEF & QRS
NYHA I
NYHA II
NYHA III–IV
LVEF ≤35%, LBBB, QRS ≤120 ms
R
M
A
LVEF ≤35%, LBBB, QRS 120–149 ms
M
A
A
LVEF ≤35%, LBBB, QRS ≥150 ms
A
A
A
LVEF ≤35%, Non-LBBB, QRS ≥150 ms
M
M
A
CRT: Nonischemic Cardiomyopathy
CRT response in nonischemic CM is variable. Appropriateness is lower than ischemic CM for the same LVEF/QRS/NYHA combination.
ICD Generator Replacement at Elective Replacement Indicator
At device end-of-life, decisions must account for current LVEF, arrhythmia history, and whether ICD indication persists. Options: replace ICD, downgrade to pacemaker, or upgrade to CRT-ICD.
Primary Prevention ICD at Initial Implant: Now at ERI
Clinical Scenario
Recommendation
AUC
No clinically relevant VT/VF, LVEF ≤35%
Replace with ICD
A
LVEF improved to >35%, pacemaker-dependent
Replace with Pacemaker
A
Now meets CRT criteria (LBBB, QRS ≥120 ms)
Upgrade to CRT-ICD
A
Dual-Chamber ICD (vs. Single-Chamber)
Most ICD candidates receive dual-chamber devices. Single-chamber systems are reserved for situations where atrial lead is unnecessary or contraindicated (e.g., permanent AF, no bradycardia pacing need).
Clinical Scenario
AUC
Standard dual-chamber ICD: intact sinus function
A
Single-chamber ICD: permanent AF, no pacing indication
A
Totally Subcutaneous ICD (S-ICD)
S-ICDs eliminate transvenous lead complications but provide limited bradycardia pacing. Appropriate for primary/secondary prevention with LVEF ≤35% and no pacing indication.
Clinical Scenario
AUC
LVEF ≤35%, no pacing indication, vascular access difficult
A
LVEF ≤35%, CKD/dialysis with high infection risk
A
Limitation: S-ICD cannot provide bradycardia pacing. Patients requiring pacing, AF with slow ventricular response, or CRT are not candidates.
ICD in LVAD Support and Heart Transplant
LVAD With Pre-Existing ICD
In LVAD-supported patients with existing ICD, continue therapy if history of sustained VT/VF. De novo ICD implantation is rarely appropriate in LVAD.
Management Strategy
AUC
Keep ICD on while on LVAD (prior VT/VF history)
M
De novo ICD in LVAD patient for primary prevention
History of multiple cellular/antibody-mediated rejection
A
Evidence of cardiac allograft vasculopathy (CAV)
M
LVEF <35% post-transplant
M
Leadless Pacing and Bradycardia Pacing
Leadless pacemakers eliminate transvenous lead complications. Appropriate for bradycardia indications with limited vascular access or high infection risk.
Clinical Scenario
AUC
Long-standing AF, normal LVEF, vascular access limited
Conduction System Pacing (HBP or Left Bundle Area Pacing)
Conduction system pacing delivers impulses directly to His bundle or left bundle area, maintaining normal electrical activation. Emerging data suggest improved outcomes vs. RV pacing.
Clinical Scenario
AUC
Sinus node dysfunction, intact AV conduction, normal QRS
A
Mobitz Type II or third-degree AV block, narrow QRS
A
Third-degree AV block with LBBB (wide QRS)
M
Emerging Technology: CSP shows promise in avoiding RV pacing-induced cardiomyopathy and may improve CRT response. Data are still evolving.
Comorbidities and Rarely Appropriate Indications
Device implantation is rarely appropriate when comorbidities substantially reduce life expectancy to <1 year or prevent meaningful clinical benefit.
Comorbidity / Circumstance
AUC
Life expectancy <1 year from noncardiac causes
R
Cognitive impairment, unable to provide consent, no proxy
R
Advanced psychiatric illness aggravated by implantation
R
Active IV drug use, unresolved bacteremia
R
Severe CKD on dialysis, NYHA Class IV, poor prognosis
M
Age ≥90 years, NYHA Class IV, multiple comorbidities
M
Do NOT Implant ICD if:
Life expectancy <1 year (cardiac or noncardiac)
Unresolved severe infection precluding safe implantation
Patient explicitly declines device therapy
No reasonable expectation of meaningful survival beyond 1 year
Always Ensure:
Shared decision-making has been conducted and documented
Patient or legal proxy understands benefits, risks, and alternatives
Clinical trial opportunities are considered
Specific reasons for "Rarely Appropriate" decisions are documented
Related Calculators & Decision Support Tools
Use these validated calculators alongside the AUC guidelines to estimate SCD risk, CRT response likelihood, and HF prognosis.