Diagnosis of Arrhythmias in Syncope by Pocket-ECG III® or Conventional Holter
Diagnosis of Arrhythmias in Syncope by Pocket-ECG III® or Conventional Holter
The purpose of this study is to determine whether continuous cardiac telemetry with the
 Pocket-ECG III® system is more useful than conventional Holter to find out the cause of
 syncope
Study population: adult patients with recurrent and/or with probable cardiac origin syncopes
 with indication of cardiac rhythm monitoring.

 Estimated sample size: COLAPS trial showed that conventional 48-hours Holter and 4-weeks
 external loop recorder got a diagnosis in 22% and 56%, respectively, in patients with
 syncope. Based on this data, to compare two matched-proportions with α-risk=0.05 and
 β-risk=0.2, 34 patients would be needed; to compensate a 15-20% percentage of lost patients
 during follow-up, it is estimated that 40 patients is the number to include in the trial to
 demonstrate the effect.

 Variables to collect:

 Baseline variables: birthdate date (month, year), inclusion date, gender, number and features
 of syncopes, cardiovascular risk factors, electrocardiogram, type of cardiopathy, left
 ventricular ejection fraction, comorbidities and treatments.

 Monitoring findings: diagnostic event and diagnostic fulfilled criteria, date of diagnostic
 event, date of last follow-up.

 Safety and adverse events: monitoring length, unexpected battery depletion, number of losses
 of mobile phone signal, cutaneous reactions to electrodes.

 Costs: the costs of every diagnostic procedure used from inclusion to the end of follow-up
 will be added, based on prespecified costs of every item (Decreto 56/2014 of the Consellería
 de Sanidade de la Xunta de Galicia, which specifies the costs of every diagnostic or
 therapeutic intervention in centers depending on the Servicio Gallego de Salud).

 Intervention description: patients with indication of conventional Holter monitoring will be
 consecutively included. After signing written informed consent, a Pocket-ECG III® system will
 be given to the patient. All participants will be monitored by the Pocket-ECG III® system
 until a diagnosis is achieved or for a maximum of two months (whatever it happens first).
 Everyday daily reports sent via e-mail by the manufacturer company (MEDICALgorithmics© S.A.)
 will be reviewed by the investigator team; in case of a diagnosis event (according to
 prespecified diagnostic criteria from the European Society of Cardiology), appropriate
 treatment will be applied.

 Every patient will be his/her own control. Conventional 24-hours Holter monitoring will be
 simulated using data obtained by the Pocket-ECG III® system in the first 24 hours, ignoring
 the registries of the rest of days. Two and Three 24-hours conventional Holter strategies
 will also be simulated analyzing data from first 24 hours and 1-2 additional days,
 respectively, chosen by means of a random number creation system which will identify the days
 of registry to be considered. Diagnostic criteria in this virtual control group will be the
 same as used in the actual Pocket-ECG III® system monitoring group.

 Follow-up: patients will be followed-up by two complementary manners

 1. Real-time remote: Pocket-ECG III® system sends continuously the registered
 electrocardiogram sinal via GSM mobile phone to a central unit sited in Poland, where
 the signal is processed and interpreted. From this central unit, a daily report and a
 weekly summary report is sent by e-mail to the investigator team. If a lost in the
 mobile phone coverage happens, the system stores the registry in its memory until the
 coverage is recovered, when the whole stored registry is sent.

 2. Purpose-created outpatient clinic.

 Statistical methods: categorical variables will be expressed as "absolute number
 (percentage)" and continuous variables as "mean ± standard deviation", adding "median
 (interquartile range)" when the distribution of values is far from normal distribution
 assessed by Kolmogorov-Smirnov and Shapiro-Wilk methods. Proportion of diagnosis achieved by
 each strategy will be compared by McNemar for intrasubject measures or binomial exact
 methods, whichever applies. Economic burden of each strategy will be compared with the
 t-Student for intrasubject measures or T de Wilcoxon methods, whichever applies. All tests of
 significance will be 2-sided, with p<0.05 considered statistically significant. The analysis
 will be conducted using PASW Statistics version 18.0 (IBM, Armonk, New York) and EPIDAT 3.1
 (provided by the Direccion Xeral de Saude Publica de la Consellería de Sanidade de la Xunta
 de Galicia).
Inclusion Criteria:

 -  Patients with syncope refered to perform 24-hours conventional Holter who fulfill at
 least one of the following conditions:

 1. ≥2 episodes of syncope in the last year, provided that they are not typical
 vasovagal syncope, and/or

 2. ≥1 episode of syncope with any criterion of suspicion of cardiac-arrhythmic
 aetiology, according to current European Guidelines about management of syncope

 Exclusion Criteria:

 -  Carrier of any cardiac implantable electronic device or internal loop recorder, as
 well as stablished indication for it according to current guidelines.

 -  Aetiologic diagnosis of syncope already known.

 -  Left ventricular ejection fraction ≤35%.

 -  Unability to perform the monitorization