Seventy-seven year old man implanted with a CRT-D InSync Sentry for valvular cardiomyopathy and poor ejection fraction.
Discriminators used in single chamber ICDs (Stability, Sudden-onset and morphology) may or may not be incorporated into dual chamber discriminators. Dual chamber discriminators are based on a continuous analysis of 6 criteria looking for the atrio-ventricular relationship (PR logic). It is important to note that the sudden onset and the stability criteria take precedence over the PR logic. In the present case, the PR logic is not used to make the diagnosis of AF since the stability criterion is not fulfilled.
Three detection zones are programmed (VF, FVT via FV, VT); discriminators are effective only in the VT zone; the PR logic is turned ON and the stability criteria is programmed at 40ms; the episode is labeled SVT in the absence of ventricular stability suggesting an episode of atrial fibrillation ; consequently no therapy is delivered.
