Optimal Candidates for
Cardiac Rhythm Devices
in heart failure
Cardiac Resynchronization Therapy
Who would be most beneficial from CRT?
Benefits of CRT by QRS duration
QRS<130 LBBB: QRS≥130 non-LBBB: QRS≥150
Benefits of CRT by NYHA & LVEF
Data on NYHA I was from MADIT-CRT. Data on NYHA II-IV was from the same meta-analysis.
Current Indications for CRT
QRS duration and morphology
QRS<130 LBBB: QRS≥130 non-LBBB: QRS≥150
NYHA I if LBBB with QRS≥150 NYHA II-ambulatory IV
LVEF≤35% HF with anticipated RV pacing of >40%
Current class I indications for ICD for primary prevention of sudden cardiac arrest
>40d post MI or >90d post revascularization
Stable HF; ischemic or non-ischemic ≤35%II-III SCD-HeFT
Recent MI, NSVT, +EP Study ≤40%Any MUSTT
Rates of sudden cardiac death declined substantially over time.

Benefits of ICD by Seatle Heart Failure Model
What is Seatle Heart Failure Model?
Model to evaluate risks for... ×
The Seattle Heart Failure Model (SHFM) is a calculator of projected survival at baseline and after interventions for patients with heart failure.
The Seattle Proportional Risk Model (SPRM) is a calculator of estimated proportion of sudden death in patients with heart failure with reduced ejection fraction (primarily EF≤35%) to illustrate the variable the benefit of a primary prevention ICD.
Wearable ICD
Reasonable as a bridge to transplantation or re-implantation due to transient interruption such as infection.
May be considered as bridging therapy in situations associated with increased risk of death in which ICDs have been shown to reduce SCD but not overall survival such as within 40 days of MI.

Cardiac Contractility Modulation
A device-based therapy for heart failure (HF) that involves applying biphasic electric signals to the right ventricular septal wall during the absolute myocardial refractory period.
Been shown to improve quality of life in those with LVEF 35-45% and narrow QRS.
  • LVEF, NYHA class, and QRS duration remain the major indicators for cardiac rhythm devices in heart failure.

  • Age, sex, etiology, and comorbidities can further delineate who would be most beneficial from device therapy.