Gender-related differences on signal-averaged electrocardiograms in healthy subjects

A novel signal-averaged electrocardiogram and an ambulatory-based signal-averaged electrocardiogram show strong correlations with conventional signal-averaged electrocardiogram in healthy subjects: A validation study

BACKGROUND

A novel signal-averaged electrocardiogram (SAECG) device and a novel ambulatory SAECG device are clinically available, but reference values have not been established. This study aimed to validate the novel SAECG and the novel ambulatory-based SAECG devices by comparison with the conventional SAECG device.

METHODS AND RESULTS

High-resolution SAECGs were recorded consecutively in 83 healthy volunteers using the 3 devices. A novel ambulatory SAECG device was used as real-time recording within 15 min for validation study (15 min ambulatory-based SAECG). We examined the concordance of positive results (at least 2/3 abnormal SAECG parameters) and negative results (0 or 1/3 abnormal parameters), as well as the correlations between SAECG parameters (filtered QRS duration [fQRS]); duration of low-amplitude signals < 40 μV in the terminal filtered QRS complex [LAS₄₀]; root mean square voltage of the terminal 40 ms of the filtered QRS complex [RMS₄₀]). Qualitative analysis showed excellent concordance among the novel SAECG, the 15 min ambulatory-based SAECG, and the conventional SAECG methods (novel SAECG vs. conventional SAECG = 94%; 15 min ambulatory-based SAECG vs. conventional SAECG = 91.6%; p = 0.755), while quantitative analysis indicated strong correlations between the novel SAECG and the conventional SAECG values for fQRS, LAS₄₀, and LnRMS₄₀ (r = 0.838-0.805, p < 0.0001, respectively). Strong correlations were also seen between 15 min ambulatory-based SAECG and conventional SAECG values for fQRS, LAS₄₀, and RMS₄₀ (r = 0.943-0.888, p < 0.0001, respectively). However, Bland-Altman quantitative analysis showed better agreement in fQRS and LnRMS₄₀ measured by the 15 min ambulatory-based SAECG and the conventional SAECG than those by the novel SAECG and the conventional SAECG (fQRS, Lin's rho_c = 0.923 vs. 0757; RMS₄₀, Lin's rho_c = 0.932 vs. 0.818, respectively).

CONCLUSION

In healthy subjects, the parameters of either the novel SAECG or the 15 min ambulatory-based SAECG and those of the conventional SAECG were strongly correlated. Relatively good agreements were observed among 3 SAECGs, especially better between the 15 min ambulatory-based SAECG and the conventional SAECG probably due to similar measurement system of 2 methods.

Lack of correlation between ventricular late potentials and left ventricular mass in top-level male athletes

PURPOSE

The aim of this study was to establish: 1) the prevalence of abnormal signal-averaged electrocardiogram (SAECG) in a large population of top-level athletes and 2) the relationship between SAECG parameters and left ventricular mass. One-hundred and fifty-three elite male athletes without apparent heart disease, symptoms, or arrhythmias were studied.

METHODS

Fifty-six athletes (37%) had increased left ventricular mass (> 134 g.m(-2)). All athletes underwent time-domain SAECG on 300-400 heart beats recorded at rest from three bipolar orthogonal tests with a filter setting of 40-250 Hz. Criteria for abnormality were 1) filtered QRS duration > 114 ms, 2) duration of low-amplitude signals > 38 ms, or 3) root mean square voltage of the last 40 ms of the filtered QRS < 20 microV.

RESULTS

The prevalence of abnormal SAECG was 7.2% (abnormality of one parameter), 6.5% (abnormality of two parameters), and 5.8%(abnormality of three parameters). The prevalence of abnormal SAECG was similar in athletes with or without increased left ventricular mass.

CONCLUSIONS

In conclusion, this study showed: 1) the low rate of positive results of SAECG parameters in top-level male athletes, similar to that found in healthy sedentary subjects; and 2) the lack of correlation between left ventricular mass and overall SAECG parameters.

Gender differences in presentation, management, and cardiac event-free survival in patients with syncope

In a MEDLINE search of published English studies (1966 to 1996), no prior study was identified that examined gender-based differences in the management and prognosis of patients admitted with syncope. We studied 109 consecutive patients (48 women) admitted with syncope at the Massachusetts General Hospital (1989 to 1990). All patients underwent Holter monitoring, signal-averaged electrocardiography, and echocardiography according to study protocol. Follow-up was 100% complete (10 +/- 4 months). Women were older (74 +/- 2 vs 66 +/- 2 years, p <0.01) and less likely to have premonitory symptoms when compared with men (46% vs 66%, p <0.05). A greater proportion of men had left ventricular ejection fractions of <0.40 (18% vs 0%, p <0.01), abnormal signal-averaged electrocardiograms (28% vs 8%, p <0.01), and a cardiac cause for syncope (49% vs 25%, p <0.01). Although referral for diagnostic electrophysiologic testing was >3 times as frequent for men compared with women (20% of men vs 6% of women, p <0.05), this difference was not significant after adjustment for age, ventricular arrhythmia, and referral for coronary angiography. During follow-up, 21% of men versus 6% of women (p <0.05) had cardiac events (recurrent syncope, myocardial infarction, or sudden death). Cardiac event-free survival rates were worse for men (p = 0.045). Thus, we have identified gender-based differences in the clinical presentation of syncope for hospital admission. Left ventricular dysfunction and an abnormal signal-averaged electrocardiogram occur more frequently in men. Men are more likely to have cardiac syncope and worse cardiac event-free survival when compared with women.

Signal-averaged electrocardiography in healthy children: relationship with age, sex, and anthropometry

Signal-averaged electrocardiograms (SAECGs) have been found to be influenced by sex and anthropometry in adults. The purpose of this study was to evaluate this relationship in children. Total filtered QRS duration (TQRS), duration of high-frequency, low-amplitude signals in the terminal portion of the QRS complex that were less than 40 microV (HFLA) root-mean-square voltage in the last 40 ms of the filtered QRS (RMS40) were determined by high-resolution electrocardiographic (ECG) recording (MAC 15 ECG System, Marquette Electronics, Milwaukee, WI). These parameters were correlated with age, sex, body weight, height, relative weight, body mass index, and body surface area. As HFLA and RMS40 were not normally distributed, they were logarithmically transformed for regression analysis. The best subset multiple regression procedure was used to evaluate the variables that would optimally influence SAECG measurements and to obtain regression equations for the prediction of each SAECG parameter. Although univariate analysis shows that almost all the body characteristics and age are significantly correlated with SAECGs, multiple regression analysis reveals that TQRS is significantly influenced by height (P < .0001), relative weight (P = .012), and body mass index (P = .041); HFLA is influenced by weight (P = .001), height (P = .004), and body mass index (P = .001); and RMS40 is influenced by height (P < .0001) and relative weight (P = .001). Sex is noted to significantly influence both TQRS and RMS40 (P < .0001, P = .002, respectively), while HFLA is found to be significantly related to age (P = .001). In summary, SAECGs in Chinese children are shown to be influenced by height, weight, and relative weight or body mass index, but not body surface area, while age and sex also significantly contribute to the variation of some SAECG parameters.