Efficacy of automatic mode switching in DDDR mode pacemakers: the most 2 study.

<bold>Background: </bold>Effective automatic mode switching (AMS) algorithms capable of detecting a range of supraventricular tachyarrhythmias is important given evidence of atrial fibrillation (AF), atrial flutter (AFL), and atrial tachycardia (AT) post-implantation of pacemakers.<bold>Objectives: </bold>The aim of the study was to assess the efficacy, defined as ability to detect a specific atrial rate and activate AMS, of five different AMS mechanisms during simulation of AF, AFL, and AT.<bold>Materials and Methods: </bold>A total of 48 subjects (35 men, 13 women; mean age: 69 +/- 8 years) implanted with DDDR pacemakers utilizing five different AMS mechanisms (mean atrial rate, rate cut-off, complex 'fallback' algorithm, retriggerable atrial refractory period, and physiological band 'beat-to-beat') were tested using an external electronic device that simulated the occurrence of supraventricular tachyarrhythmias. AF, AFL, and AT were simulated by delivering low voltage pulse trains at 350, 250 and 160 beats/min, respectively.<bold>Results: </bold>Mean efficacy for all AMS mechanisms was 81% [range: 57% to 100%] at 350 beats/min, 81% [range: 57-100%] at 250 beats/min, and 79% [range: 57-100%] at 160 beats/min. The AMS mechanisms that yielded 100% efficacy were the rate cut-off and physiological band 'beat-to-beat.'<bold>Conclusion: </bold>Not all AMS algorithms are equally efficacious at detecting atrial arrhythmias and subsequently activating AMS. Our results suggest that the most efficacious AMS algorithms are those that use rate cut-off and physiological band 'beat-to-beat' to detect supraventricular tachyarrhythmias. [ABSTRACT FROM AUTHOR]