  Detection of atrial fibrillation (AF), a type of cardiac arrhythmia, is
difficult since many cases of AF are usually clinically silent and undiagnosed.
In particular paroxysmal AF is a form of AF that occurs occasionally, and has a
higher probability of being undetected. In this work, we present an attention
based deep learning framework for detection of paroxysmal AF episodes from a
sequence of windows. Time-frequency representation of 30 seconds recording
windows, over a 10 minute data segment, are fed sequentially into a deep
convolutional neural network for image-based feature extraction, which are then
presented to a bidirectional recurrent neural network with an attention layer
for AF detection. To demonstrate the effectiveness of the proposed framework
for transient AF detection, we use a database of 24 hour Holter
Electrocardiogram (ECG) recordings acquired from 2850 patients at the
University of Virginia heart station. The algorithm achieves an AUC of 0.94 on
the testing set, which exceeds the performance of baseline models. We also
demonstrate the cross-domain generalizablity of the approach by adapting the
learned model parameters from one recording modality (ECG) to another
(photoplethysmogram) with improved AF detection performance. The proposed high
accuracy, low false alarm algorithm for detecting paroxysmal AF has potential
applications in long-term monitoring using wearable sensors.
