Performance of a new single-chamber ICD algorithm: discrimination of supraventricular and ventricular tachycardia based on vector timing and correlation.

Aims Interval- and morphology-based algorithms have been used in modern implantable cardioverter clefibrillators (ICDs) to discriminate supraventricutar tachycardia (SVT) from other rhythms. A newly developed ICD discrimination algorithm, Rhythm ID ThA (Guidant Corporation, St Paul, MN, USA), uses both interval-based metrics and an electrogram vector timing and correlation (VTC) algorithm in a dual-chamber ICD. In a single-chamber ICD, Rhythm ID contains only the VTC component. This study conducted a retrospective analysis of the performance of Rhythm ID for the detection of induced and spontaneous rhythms in a single-chamber ICD. Methods and results This study gathered the data from a prospective, multicentre clinical trial. Ninetysix patients were implanted with a dual-chamber ICD. For this study, each episode was analysed to determine the performance of the single-chamber ICD Rhythm ID algorithm. The mean age of the patients implanted with the device was 67 +/- 11 years. Seventy-eight patients were mate. The primary cardiovascular disease was coronary artery disease and the primary tachyarrhythmia was monomorphic ventricular tachycardia (VT). The mean follow-up time was 11.4 months. A total of 369 induced and spontaneous ventricular arrhythmias was analysed. The algorithm detected 100% of ventricular arrhythmias. Four hundred and forty-two SVT episodes were analysed, including 145 induced and 297 spontaneous. The SVTs were atrial. fibrillation (n = 199), atrial flutter (n = 135), and 1: 1 SVT (n = 108). The singte-chamber ICD Rhythm ID algorithm successfully discriminated 403 SVT episodes and achieved a specificity of 91%. Conclusion The single-chamber version of Rhythm ID demonstrated high specificity without compromising sensitivity.