New ICD morphology criterion for differentiation of supraventricular and ventricular tachycardia

The high incidence of inappropriate therapies due to supraventricular tachy cardia remains a major unsolved problem of the implantable cardioverter def ibrillator. A new morphology discrimination (MD) algorithm has been introdu ced to improve specificity of ICD therapy without loss of sensitivity. It w as the aim of this study to systematically analyze sensitivity and specific ity of the MD criterion in combination with the enhanced detection criteria sudden onset and rate stability in the detection of ventricular and suprav entricular tachycardia. After ICD implantation in 259 patients, 787 detected episodes in 74 patient s with available stored electrograms were documented during a follow-up per iod of 359+/-214 days. With a nominal programming of the MD algorithm at >6 0%, sensitivity and specificity for all episodes were 82.6%/77.2%. For sinu s tachycardia, atrial fibrillation and atrial flutter the specificities wer e 80.6%, 69.6% and 75%, respectively. In patients with primarily appropriat e MD detection, sensitivity and specificity significantly improved to 95.8% /91.7%. Programming the sudden onset criterion with <100 ms and the stabili ty criterion with <50 ms, sensitivity and stability of the combined applica tion of the MD algorithm and sudden onset and MD algorithm and stability we re 96.2%/52.2% and 94.4%/ 63.8%, respectively. The MD criterion in combination with other enhanced detection criteria migh t significantly improve specificity of tachyarryhthmia detection of ICD the rapy.