Small decreases in biventricular pacing percentages are associated with multiple metrics of worsening heart failure as measured from a cardiac resynchronization therapy defibrillator.

BACKGROUND: Lower BiVentricular (BiV) pacing percentages have been associated with significantly worse survival in patients with chronic heart failure (HF). However, the pathophysiology behind this observation has not been further delineated. This analysis evaluated whether small incremental decreases in BiV pacing percentages were associated with worse measures, related to HF physiology using individual sensor trends and the HeartLogic composite index. METHODS: Sensor data was obtained from 900 ambulatory HF patients with implanted CRT devices. The percent of cardiac cycles with BiV pacing was assessed for periods (median = 7.3 days) between data downloads (median = 55 periods/patient). RESULTS: The third heart sound (S3), respiration rate, RSBI, and night-time heart rate were significantly elevated with sub-optimal pacing (<98%), while the first heart sound (S1), thoracic impedance, and activity were significantly lower. All sensor changes were in the direction associated with worsening HF. While IN the HeartLogic alert state (threshold above an Index of 16) the odds of optimal BiV pacing (≥98%) were less than when OUT of the HeartLogic alert state for a given subject (OR: 0.655; 95% CI: 0.626-0.686; p < 0.0001). The percent BiV pacing was reduced and the HeartLogic Index was increased in the periods surrounding HFhospitalizations. CONCLUSION: Lower BiV pacing percent is associated with multiple sensor changes indicative of worsening HF, and patients in HeartLogic alert are more likely to have suboptimal BiV pacing. Collectively, these data provide strong evidence that even small decreases in BiV percent pacing can lead to worsening HF.

Inadvertent Disabling of Implantable Cardiac Defibrillator Antitachycardia Therapies Following Breast Reconstructive Surgery.

A 47-year-old woman with an implantable cardiac defibrillator and breast cancer underwent left breast mastectomy with simultaneous reconstruction using a breast tissue expander. She was found to have intermittent disabling of tachyarrhythmia detection and therapy functions of her implantable cardiac defibrillator that were triggered by the breast tissue expander magnetic port.

The impact of atrial prevention and termination therapies on atrial tachyarrhythmia burden in patients receiving a dual-chamber defibrillator for ventricular arrhythmias.

INTRODUCTION: This prospective, multicenter, randomized trial evaluated the effects of atrial prevention and termination therapies on atrial tachyarrhythmia (ATA) burden in patients with a standard indication for an implantable cardioverter defibrillator (ICD). METHODS: A Jewel AF or GEM III AT ICD was implanted in 451 patients. At 1-month post-implant, patients were randomized to atrial prevention and termination therapies ON ( n = 199) or OFF ( n = 206) and followed for 6 additional months. Automatic atrial shocks were enabled in only 14% of the ON group. The follow-up time after randomization was 6.9 +/- 2.4 months ON versus 6.8 +/- 2.3 months OFF. RESULTS: There were 126/405 (31.1%) patients who had AT/AF episodes during follow-up. Only four patients received a shock to treat ATA's during follow-up. The median ATA burden was 0 hours/month in both the ON and OFF groups ( P = 0.40). The mean ATA burden was 4.3 +/- 20.0 hours/month ON versus 9.0 +/- 50.0 hours/month OFF ( P = 0.11). In a subgroup of 192 patients with a history of ATA's, the median burden was 0 hours/month in the both groups ( P = 0.23). However, the mean burden in this subgroup was 7.6 +/- 27.1 hours/month ON versus 19.2 +/- 73.7 hours/month OFF ( P = 0.056). CONCLUSIONS: In patients receiving an ICD for ventricular arrhythmias, no significant change in ATA burden was observed when atrial prevention and termination therapies were enabled. This may have been due to the low ATA burden in this population. In a subgroup of patients with history of ATA's, there was a trend towards a reduction in mean burden.

Usefulness of implantable loop recorders in office-based practice for evaluation of syncope in patients with and without structural heart disease.

Early use of an implantable loop recorder for evaluating unexplained syncope in an office-based electrophysiology practice is an effective approach in patients with and without structural heart disease. Documentation of rhythm with an implantable loop recorder at the time of symptoms is possible in approximately 50% and 80% of patients in both groups after 1 and 2 years of follow-up, respectively.