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Background: Accurate measurement of QRS complex duration (QRSd) remains crucial for the selection of patients for cardiac resynchronization therapy (CRT). However, assessment of QRSd on conventional surface electrocardiograms (ECG), especially when performed without computer assistance, may be challenging due to the limited accuracy of the human eye to discriminate differences in the range of 10 ms at 25 mm/s. The value and reproducibility of visual assessment of QRSd at 25 mm/s on conventional ECGs was compared to those obtained using an electrophysiology recording system (EPRS) with simultaneous 12 lead traces at 100 mm/s, which was considered the gold standard.Methods: The ECGs of 102 consecutive patients with left ventricular dysfunction undergoing electrophysiological evaluation were collected. Two sets of measurements were obtained: 1) QRSd-25 measured on conventional 12-lead ECGs printed at 25 mm/s with standard amplification (10 mm/mV) by 4 different observers, and 2) QRSd-100 measured on simultaneous 12-lead traces at 100 mm/s and 40 mm/mV by 2 different observers using electronic callipers.Results: Significant differences were observed between QRSd-100 and QRSd-25 measurements (19.3 ± 9.9 ms, range 1.0-47.5, p < 0.001). QRSd-25 showed significant inter and intra-observer variability. When categorizing individual ECGs in three QRSd-25 subgroups (<120 ms, 120-149 ms and ≥150 ms), low concordance was observed between both techniques (kappa index 0.25, p < 0.001). The sensitivity and specificity of QRSd-25 to detect QRSd-100 ≥ 150 ms was 36.6% and 100.0% respectively.Conclusions: Visual measurement of QRSd at 25 mm/s often underestimates its magnitude and presents significant inter and intraobserver variability. [ABSTRACT FROM AUTHOR]

Background Brugada syndrome (BrS) is a heritable sudden cardiac death (SCD) disease with male predominance. Information on gender difference of BrS remains scarce. Aim To investigate the gender difference of BrS in Han Chinese. Design We consecutively enrolled 169 BrS patients (153 males and 16 females) from Han Chinese in Taiwan from 1998 to 2017. Methods Clinical characteristics, electrocardiographic parameters and SCN5A mutation status were compared between genders. Results The percentage of family history of SCD in females was slightly higher (31.3% vs. 15%, P  =   0.15). Females exhibited longer QTc (457.8 ± 33.0 vs. 429.5 ± 42.1 ms, P  <   0.01). Regarding cumulative event occurrence by age, Mantel-Cox test showed females had earlier age of onset of first cardiac events (SCD or syncope) than males (P  =   0.049), which was mainly attributed to syncope (P  <   0.01). Males with SCD exhibited longer QRS duration (114.2 ± 26.8 vs. 104.8 ± 15.3 ms, P  =   0.02) and QTc (442.5 ± 57.4 vs. 422.9 ± 28.8 ms, P  =   0.02). Males with syncope exhibited longer PR interval (181.2 ± 33.7 vs. 165.7 ± 27.1 ms, P  =   0.01), whereas females with SCD or syncope had a trend towards slower heart rates (69.1 ± 9.6 vs. 82.2 ± 16.3 bpm, P  =   0.10) than female with no or mild symptoms. There was no difference in the percentage of SCN5A mutation between genders. Conclusion Gender difference is present in BrS. Females have longer QTc and suffer from syncope earlier than males. Risk of SCD in males is associated with boarder QRS complex and longer QTc, whereas risk of syncope is associated with longer PR interval in males and slower heart rate in females. [ABSTRACT FROM AUTHOR]

Aims: To test the hypothesis that the QS interval of ventricular ectopic beats (VEBs) (ventricular ectopic QS interval, VEQSI) would provide a marker for the presence of structural heart disease and a predictor of mortality. [ABSTRACT FROM PUBLISHER]

Background: Prediction of response to cardiac resynchronization therapy (CRT) is still an unsolved major issue. The interface between left ventricular mechanics, coronary sinus (CS) lead, and pacing delivery has been little investigated., Objective: To investigate CS lead tip movements at baseline and during biventricular pacing (BiV) in the hypothesis that they could provide some insights into left ventricular mechanical behavior in CRT., Methods: Three-dimensional reconstruction of CS lead tip trajectory throughout the cardiac cycle using a novel fluoroscopy-based method was performed in 22 patients with chronic heart failure (19 men; mean age 70 ± 10 years). Three trajectories were computed: before (T-1) and immediately after (T0) BiV start-up and after 6 months (T1). CRT response was the echocardiographic end-systolic volume reduction ≥15% at T1. Metrics describing trajectory at T0, T-1, and T1 were compared between 9 responders (R) and 13 nonresponders (NR)., Results: At T-1 trajectories demonstrated heterogeneous shapes and metrics, but at T0 the variations in the ratio between the two main axes (S1/S2) and in the eccentricity were statistically different between R and NR, pointing out a trajectory's change toward a significantly more circular shape at BiV start-up in R. Remarkably, R and NR could be completely separated by means of the percent variation in S1/S2 from T-1 to T0 (R: 47.5% [31.5% to 54.1%] vs. NR: -25.6% [-67% to -6.5%]). This single marker computed at T0 would have predicted CRT response at T1., Conclusions: Preliminary data showed that CS lead tip trajectory changes induced by BiV were related to mechanical resynchronization., (© 2013 Heart Rhythm Society. All rights reserved.)