Fig 1.
Flow diagram demonstrating the number of patients enrolled.
During the study period, 315 patients were enrolled. The patients were then separated into two groups: with and without a history of aborted sudden cardiac death (SCD). Propensity analysis was performed to minimize the confounders, and the cases and controls were matched at a 1:2 ratio using a 0.10 caliper for identical characteristics of age, sex, and histories of hypertension and coronary artery disease. Ultimately, there were 59 patients with a history of aborted SCD and 103 control patients without a history of aborted SCD. (Abbreviations: Hx, history; LV, left ventricular; SCD, sudden cardiac death).
Fig 2.
Representative examples showing the 12-lead surface electrocardiogram (ECG) and the reconstruction vectors.
The difference is subtle by visual inspection on surface ECG (upper part); however, a substantial difference is observed on the basis of the QRS descriptors (lower part). These examples show a lower PL in the patients with a history of aborted sudden cardiac death than in the controls. (Abbreviations: PL, percentage of the loop area).
Table 1.
Baseline characteristics of the patients with SCD or without SCD history.
Table 2.
Baseline characteristics of the propensity matched patients.
Fig 3.
Comparison of the box plots derived from three variables in the two groups.
The sudden cardiac death (SCD) group had a significantly greater V4-5 dispersion (p<0.01, panel A), smaller percentage of the loop area (p<0.01, panel B), and longer QRS duration (p<0.01, panel C) than the control group. Boxes in the box plots start in the first quartile, end in the third quartile, and represent 50% of the central data. A line inside represents the median values. In these box plots, black dots present the distribution of the data, and empty dots exhibit the location of the outliers and line centrally. A data dot is said to be an outlier if it is greater than the third quartile of data plus 1.5 times the interquartile range (high outlier) or less than the first quartile of data minus 1.5 times the interquartile range (lower outlier). Therefore, upper lines represent the maximum value in the dataset without high outliers, and lower lines represent the minimum value in the dataset without lower outliers. (Abbreviations: SCD, sudden cardia death).
Table 3.
OR for aborted SCD history in univariate and multivariate logistic regression.
Fig 4.
Box plot of the comparison of percentage of the loop area (PL), V4-5 dispersion, and QRS duration in the different event number groups.
The comparisons were performed using one-way ANOVA. The x-axis represents the number of events, while the y-axis shows the units of the different values. A significant difference among the three groups was observed in the PL and V4-5 dispersion values (p<0.01). The QRS duration failed to demonstrate significance (p = 0.10). *The p-values are significant between the two groups. (Abbreviations: PL, loop area percentage).