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Effect of cardiac resynchronization therapy on occurrence of ventricular arrhythmia in patients with implantable cardioverter defibrillators undergoing upgrade to cardiac resynchronization therapy devices
  1. Grace Lin (lin.grace{at}
  1. Mayo Clinic, United States
    1. Robert F Rea
    1. Mayo Clinic, United States
      1. Stephen C Hammill (hammill.stephen{at}
      1. Mayo Clinic, United States
        1. David L Hayes (rfrea{at}
        1. Mayo Clinic, United States
          1. Peter A Brady (brady.peter{at}
          1. Mayo Clinic, United States


            Background Cardiac resynchronization therapy (CRT) improves outcomes in selected patients with heart failure and left ventricular dysfunction. One mechanism of benefit is believed to be favorable ventricular remodeling. Whether CRT also decreases the frequency of ventricular arrhythmias and risk of sudden death, is unknown.

            Objective To determine the effect of CRT on frequency of ventricular arrhythmias and appropriate ICD therapies.

            Design Retrospective cohort study

            Setting Single center, tertiary care facility (Mayo Clinic)

            Patients 52 patients (46 male), aged 70 ± 10 years, who underwent upgrade from an implantable cardioverter defibrillator (ICD) to a CRT- defibrillator were included.

            Interventions Upgrade of ICD to CRT-defibrillator

            Main Outcome Measures Frequency of ventricular arrhythmias prior to and following upgrade to CRT device.

            Results Ejection fraction increased from 22% ± 8% to 27 ± 11% following CRT. However, the frequency of non-sustained ventricular arrhythmias, sustained ventricular arrhythmias, and ventricular fibrillation was not significantly changed prior to and following CRT (2.38 ± 9.78 vs. 58.51 ± 412.73 per patient per month, p= 0.66; 0.07 ± 0.17 vs. 0.16 ± 0.52, p= 0.70; 0.05 ± 0.12 vs. 0.25 ± 1.40, p= 0.12).

            Conclusions CRT is not associated with a decrease in the frequency of ventricular arrhythmia or appropriate device therapy. Thus, use of CRT alone is not beneficial in decreasing the frequency of ventricular arrhythmias or the risk of appropriate ICD therapies.

            • cardiac resynchronization therapy
            • defibrillators
            • heart failure
            • ventricular arrhythmias

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