title: Automated detection of effective left-ventricular pacing: going beyond percentage pacing counters.
abstract: OBJECTIVE
  Cardiac resynchronization therapy (CRT) devices report percentage pacing as a diagnostic but cannot determine the effectiveness of each paced beat in capturing left-ventricular (LV) myocardium. Reasons for ineffective LV pacing include improper timing (i.e. pseudofusion) or inadequate pacing output. Device-based determination of effective LV pacing may facilitate optimization of CRT response.
  
  
  RESULTS
  Effective capture at the LV cathode results in a negative deflection (QS or QS-r morphology) on a unipolar electrogram (EGM). Morphological features of LV cathode-RV coil EGMs were analysed to develop a device-based automatic algorithm, which classified each paced beat as effective or ineffective LV pacing. The algorithm was validated using acute data from 28 CRT-defibrillator patients. Effective LV pacing and pseudofusion was simulated by pacing at various AV delays. Loss of LV capture was simulated by RV-only pacing. The algorithm always classified LV or biventricular (BV) pacing with AV delays ≤60% of patient's intrinsic AV delay as effective pacing. As AV delays increased, the percentage of beats classified as effective LV pacing decreased. Algorithm results were compared against a classification truth based on correlation coefficients between paced QRS complexes and intrinsic rhythm QRS templates from three surface ECG leads. An average correlation >0.9 defined a classification truth of ineffective pacing. Compared against the classification truth, the algorithm correctly classified 98.2% (3240/3300) effective LV pacing beats, 75.8% (561/740) of pseudofusion beats, and 100% (540/540) of beats with loss of LV capture.
  
  
  CONCLUSIONS
  A device-based algorithm for beat-by-beat monitoring of effective LV pacing is feasible.
authors: Medtronic Inc., 8200 Coral Sea St, Mounds View, MN 55112, USA.
authors: Subham
authors: S
authors: Ghosh
authors: Medtronic Inc., 8200 Coral Sea St, Mounds View, MN 55112, USA.
authors: Robert W
authors: RW
authors: Stadler
authors: Arrhythmia Institute at Valley Hospital, 223 N. Van Dien Avenue, Ridgewood, NJ 07450, USA mittsu@valleyhealth.com.
authors: Suneet
authors: S
authors: Mittal
mesh_terms: D000368:Aged; D000465:Algorithms; D058406:Cardiac Resynchronization Therapy; D058409:Cardiac Resynchronization Therapy Devices / Q000009:adverse effects; D005260:Female; D006333:Heart Failure / Q000628:therapy*; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged
keywords: Cardiac resynchronization therapy; Effective LV pacing; Electrograms; Percent pacing