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Aims: SYNARR-Flash study (Monitoring of SYNcopes and/or sustained palpitations of suspected ARRhythmic origin) is an international, multicentre, observational, prospective trial designed to evaluate the role of external 4-week electrocardiogram (ECG) monitoring in clinical work-up of unexplained syncope and/or sustained palpitations of suspected arrhythmic origin.Methods and Results: Consecutive patients were enrolled within 1 month after unexplained syncope or palpitations (index event) after being discharged from emergency room or hospitalization without a conclusive diagnosis. A 4-week ECG monitoring was obtained by external high-capacity loop recorder (SpiderFlash-T(®), Sorin) storing patient-activated and auto-triggered tracings. Diagnostic monitorings included (i) conclusive events with reoccurrence of syncope or palpitation with concomitant ECG recording (with/without arrhythmias) and (ii) events with asymptomatic predefined significant arrhythmias (sustained supraventricular or ventricular tachycardia, advanced atrio-ventricular block, sinus bradycardia <30 b.p.m., pauses >6 s). SYNARR-Flash study enrolled 395 patients (57.7% females, 56.9 ± 18.7 years, 28.1% with syncope, and 71.9% with palpitations) from 10 European centres. For syncope, the 4-week diagnostic yield was 24.5%, and predictors of diagnostic events were early start of recording (0-15 vs. >15 days after index event) (OR 6.2, 95% CI 1.3-29.6, P = 0.021) and previous history of supraventricular arrhythmias (OR 3.6, 95% CI 1.4-9.7, P = 0.018). For palpitations, the 4-week diagnostic yield was 71.6% and predictors of diagnostic events were history of recurrent palpitations (P < 0.001) and early start of recording (P = 0.001).Conclusion: The 4-week external ECG monitoring can be considered as first-line tool in the diagnostic work-up of syncope and palpitation. Early recorder use, history of supraventricular arrhythmia, and frequent previous events increased the likelihood of diagnostic events during the 4-week external ECG monitoring. [ABSTRACT FROM AUTHOR]

Aims There are gender-related differences in the QT interval measured from standard ECG tracings. However, these observations are based on a limited number of beats recorded in resting conditions. Computerized Holter techniques enable ventricular repolarization and its relationship with cardiac cycle length to be analysed long term. Previous studies used only the initial portion of the QT interval to the T wave apex (QTa) to measure ventricular repolarization; however, QTa may underestimate the total QT duration (QTe). The aims of this study were to verify whether QTa and QTe had similar rate-dependence in normal subjects and whether gender-related QTc differences observed in the resting ECG were also present in the long-term QT interval-cycle length relationship. Methods and results Twenty-four hour Holter recordings were obtained in 40 healthy young subjects, 20 females and 20 males (mean age 28±9 and 26±5 years, respectively ns). Two-channel ECG digitized signals were processed using new automatic QT analysis software (Ela Medical), which converted the 24-h recordings into 2880 30-s templates. It also measured the QT apex (QTa) QT end (QTe) and the RR interval (ms) of each template, and computed the slopes of the linear regressions of QTe and QTa values plotted against the corresponding RR interval (QTe/RR and QTa/RR). Females had a shorter RR interval than males (803±129 vs 877±86 ms, p=0·037), with longer mean QTc (420±17 vs 400±200 ms, p=0·0005). In both genders, QTa/RR slopes were steeper than QTe/RR slopes (p=0·0001). Both QTa7sol;RR and QTe/RR slopes were steeper in females than in males (QTa/RR 0·20±0·04 vs 0·16±0·03, p=0·001; QTe/RR 0·16±0·04 vs 0·13±0·03, p=0·027). Of note, QTa and QTe at fixed long cycle lengths (1000 ms) were longer in women than in men (QTa1000 330±20 vs 309±18 ms; p=0·002; QTe1000 410±17 vs 389±19 ms; p=0·002), while they did not differ at fixed short cycle lengths (600 ms). Conclusions This study demonstrates that both the initial portion of the QT interval (QTa) and the entire QT interval (QTe) are useful since QTa is more prolonged than QTe at increasing cycle lengths, and thus includes most of the heart rate dependency of ventricular repolarization. In normal subjects, both the QTc and the long-term relationship between ventricular repolarization and heart rate are affected by gender. The differences in QTa and QTe duration between males and females are more marked at long cycle lengths and disappear at short cycle lengths. Finally, this study also proves the clinical feasibility of assessing the long-term relationship between ventricular repolarization and heart rate by utilizing the automatic measurement of the QT interval from 24-h Holter recordings. [ABSTRACT FROM PUBLISHER]