Key result
Longer atrial blanking and AV intervals correlate with blanked atrial flutter in ~12% of CRT patients.
Why the study?
Atrial arrhythmias are common in heart failure patients with CRT and pose challenges for accurate detection and mode-switching in biventricular pacemakers/defibrillators.
Observational (n=60)
Blanked atrial flutter is a clinically significant complication in CRT patients that can lead to heart failure decompensation, and is associated with longer programmed atrial blanking times and AV intervals.
Blanked flutter may cause unrecognized rapid pacing and HF decompensation in CRT; leaves open optimal blanking and detection strategies.
BACKGROUND: Atrial arrhythmias are frequently observed in patients with heart failure and may be a primary cause for decompensation during cardiac resynchronization therapy (CRT). The accurate detection of organized atrial tachyarrhythmias poses a challenge to the function of mode-switching biventricular pacemakers/defibrillators. METHODS: The purpose of the study was to determine retrospectively the incidence of blanked atrial flutter and mode switch failure (2:1 lock-in), and to look for factors predisposing to this problem. A total number of 65 patients with CRT devices has been followed regularly over 18 +/- 12 months. Five patients were excluded because of chronic atrial fibrillation and reprogramming to VVIR mode. RESULTS: Seven out of 60 patients (12%) were diagnosed with blanked atrial flutter at unscheduled device interrogation. Sustained biventricular pacing at a median rate of 125/min-mimicking sinus tachycardia-resulted in rapid deterioration of heart failure and hospitalization. Mode switch failure occurred due to coincidence of every second flutter wave with atrial blanking. The group with 2:1 lock-in was programmed to longer atrial blanking times (143 +/- 34 ms vs 105 +/- 32 ms; P = 0.026) and AV intervals (126 +/- 8 ms vs 107 +/- 29; P = 0.001) than the group without lock-in. Other clinical characteristics examined did not differ between the two groups apart from a previous history of atrial fibrillation (P = 0.032). CONCLUSION: Blanked atrial flutter with rapid ventricular pacing is a clinically important problem in heart failure patients treated with CRT devices. Efforts should be made to avoid this complication by atrial lead implantation without ventricular farfield oversensing, by programming short PVAB and AV intervals, and by implementation of dedicated device algorithms.
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Strohmer et al. (2006) conducted an observational in Heart failure with CRT devices (n=60). Cardiac resynchronization therapy (CRT) devices was evaluated on Incidence of blanked atrial flutter and mode switch failure (2:1 lock-in). Blanked atrial flutter with mode switch failure occurred in 12% of CRT patients and was associated with longer programmed atrial blanking times (P=0.026) and AV intervals (P=0.001).
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