Europace Advance Access published online on June 9, 2008
Europace, doi:10.1093/europace/eun146
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Contribution of morphology discrimination algorithm for improving rhythm discrimination in slow and fast ventricular tachycardia zones in dual-chamber implantable cardioverter-defibrillators
1 Institute of Cardiology, University of Bologna, Azienda Ospedaliera S.Orsola-Malpighi, Via Massarenti 9, 40138 Bologna, Italy; 2 Cardiology Division, Azienda Ospedaliera Maggiore della Carità, Novara, Italy; 3 Cardiology Division, Ospedale G.B. Grassi, Ostia (RM), Italy; 4 Cardiology Division, Ospedale Umberto I Mauriziano Torino, Italy, Italy; 5 Cardiology Division, Spedale degli Infermi, Rimini, Italy; 6 Cardiology Division, Ospedale Civile Teramo, Teramo, Italy; 7 St. Jude Medical Italia, Milan, Italy
Aims: Morphology discrimination (MD) is an algorithm based on QRS morphology analysis, that can be used alone or in various combinations with other discriminators in order to diagnose ventricular tachycardia (VT) [the implantable cardioverter-defibrillator (ICD) may be set to diagnose VT if ‘Any’ or ‘All’ the discriminators indicate VT)].
Methods and results: We evaluated the contribution of MD in terms of Specificity (SP) and Sensitivity (SE) of rhythm discrimination in slow and fast VT zones (rates <150 bpm and between 150 and 180 bpm, respectively). Detection results (682 spontaneous episodes in 58 patients) were corrected for multiple episodes within a patient (generalized estimating equations method). Rhythm discrimination in slow VT zones was characterized by SE and SP below 80% without MD, while the use of MD alone allowed to enhance SP, maintaining SE at 96%. Use of MD in combination with other discriminators resulted in a decrease in SP (setting ‘Any’). In fast VT zones, MD allows an increase in SE for VT detection from around 82% up to approximately 94%, coupled with an SP of 95–96%., although SP is much higher with MD alone (94.8%) than with any other combination (78.4%). Both in slow and fast VT zones, use of multiple discriminators with the setting ‘All’ resulted in an unacceptable decrease in SE.
Conclusion: MD in a dual-chamber ICD in combination with a rate branch classification system makes it possible to achieve a very high SP in discriminating detected events both in slow and fast VT zones, while maintaining SE for VT detection.
Key Words: Cardioverter-defibrillators, Supraventricular tachycardia, Ventricular tachyarrhythmias, Morphology discrimination
* Corresponding author. Tel: +39 (0) 51 349858; fax: +39 (0) 51 344859. E-mail address: giuseppe.boriani{at}unibo.it
Manuscript submitted 23 January 2008. Accepted after revision 11 May 2008.