Definition and diagnosis
Arrhythmia characteristics contributing to TCM include not only the heart rate but also the arrhythmia type, duration, irregularity, and persistence [18]. An arrhythmia that is insidious, persistent, and well-tolerated is more likely to result in TCM [18]. Lack of persistent tachycardia from autonomic influences and resultant slower rates during sleep are likely to be the reasons that TCM is rare with inappropriate sinus tachycardia and postural orthostatic tachycardia syndrome. However, the average heart rate can be > 100 beats/min. There is no specific heart rate cutoff at which TCM develops, it seems to be age-dependent, and a heart rate two-times faster than the normal heart rate can be considered as a threshold for TCM [19].