Statistical analysis
The continuous and categorical variables are represented as the median (interquartile range [IQR]) and as counts (percentage), respectively. The means for continuous variables were compared using independent-sample t tests when the data were normally distributed; otherwise, the Mann-Whitney test was used. The associations of maximum heart rate, HADS-A score, and HADS-D score with palpitation score were analyzed by Pearson’s correlation. All data is analyzed using SPSS version 20.0 (SPSS, Chicago, Illinois). The differences were considered statistically significant at a P value of < 0.05 (two-sided).