Systems and methods for arrhythmia detection

A method for detecting cardiac arrhythmia, the method comprising:

• sensing a physiological signal;
• determining cardiac cycle lengths (CLs) from the sensed physiological signal over a window;
• identifying a plurality of beat patterns each including a cycle length statistic of consecutive CLs;
• generating a repetitiveness indicator of the beat pattern using the cycle length statistic;
• detecting atrial fibrillation (AF) in response to the repetitiveness indicator of the beat pattern falling below a threshold or within a range;
• and
• outputting the detected AF to a user via a user interface or to a process,
• wherein the plurality of beat patterns include CL sequences of consecutive CLs, and the repetitiveness indicator includes at least one of:
• a first count of CL sequences having substantially identical maximum CLs;
• a second count of CL sequences having substantially identical minimum CLs;
• a first count of ascending CL sequences each having two or more consecutive cardiac cycles progressively increasing by a first step size;
• or
• a second count of descending CL sequences each having two or more consecutive cardiac cycles progressively decreasing by a second step size.

A system for detecting cardiac arrhythmia, comprising:

• a heartbeat processor configured to:
• determine cardiac cycle lengths (CLs) from a physiological signal sensed from a subject;
• determine a first count of ascending CL sequences each comprising two or more consecutive cardiac cycles progressively increasing by at least a specified step size;
• determine a second count of descending CL sequences each comprising two or more consecutive cardiac cycles progressively decreasing by at least a specified step size;
• and
• generate a randomness indicator of the determined CLs using the first and second counts;
• an arrhythmia detector configured to detect atrial fibrillation (AF) using the generated randomness indication;
• and
• an output circuit configured to output the detected AF to a user via a user interface or to a process.