Implantable cardiac defibrillator (ICD)

(Circ 2019;140:e382)

• RV lead: defib & pacing (± antitachycardia pacing [ATP] = burst pacing > VT rate to stop VT); ± RA lead for dual-chamber PPM. Subcut-ICD (consider if young), but Ø pace/ATP.
• 2° prev: survivors of VT/VF arrest w/o revers cause; asx sustained VT + struct. heart dis.
• 1° prev: IHD (wait ≥40 d after MI): LVEF ≤30% or ≤35% & NYHA II–III or ≤40%, spont NSVT & inducible. NICM (wait ≥90 d after starting GDMT): LVEF ≤35% & NYHA II–III. High-risk CMP (w/o meeting above criteria): HCM, ACM, sarcoid, laminopathy, Chagas. Channelopathies: LQTS or Brugada if syncope or high-risk. ACHD: if SCD risk factors. More recently, for niCMP ICD ↓ SCD but not overall mortality (NEJM 2016;375:1221). Life expectancy must be >1 y.
• Wearable vest as bridge while waiting for ICD, but no benefit in RCT (NEJM 2018;379:1205)
• Subcutaneous ICD non-inferior in patients without PPM indication (NEJM 2020;383:526)
• Risks: inapprop shock in ~15–20% at 3 y (commonly d/t misclassified SVT); infxn; lead fx
• ICD discharge: ✓ device to see if approp; r/o ischemia; 6-mo driving ban (✓ state law)
• MRI: new devices OK; older may be OK (NEJM 2017;377:2555). Consult prescan.