I'm trying to understand the rhythm changes in the MIT BIH dataset.

In annotations, there are 2 main types. Beat annotations and rhythm annotations. Rhythm annotations (aux_notes field) contains rhythm changes. After each rhythm change point, there are empty strings till the next rhythm change.

Does that means all beats after the rhythm change are in the same rhythm till the next rhythm change?

For an example, take a look at the below wave with annotations (202 record of MIT BIH dataset from 21:19 to 21:49). MIT BIH 202 record

In the above diagram does the beats between '(N' and '(AFIB' are all normal rhythm beats? and does the beats after '(AFIB' are atrial fibrillation rhythm beats?


  • '(N' means a Normal rhythm annotation
  • '(AFIB' means an atrial fibrillation rhythm annotation


You can reproduce the above diagram via this online tool. Parameters are,

Choose input window

  • Database = MIT-BIH arrhythmia database (mitdb)
  • Record = 202

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  • Go to = 00:21:19
  • Window duration = 30 seconds

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