3.3.5Diagnostic Test: implantable event recorder - patient activated

StudyParticipantDiagnostic tests
Donateo 2003
case series; study held in Italy.
Setting: Hospital several departments. multicentre in Italy.

Funding: not stated
TLoC population: patients with a history of recurrent syncope but 12-lead ECG normal. Prior tests: All patients had at least 1 prior test.
history, examination, ECG, carotid sinus massage, echo and 24-hour ambulatory ECG not diagnostic; some pts also had EPS; ATP test and tilt test positive
Definition of TLoC: “adenosine sensitive syncope”.
Inclusion criteria: over 40 years old; 3 or more previous syncopes; at least 6 months between 1st and last episode; clinically severe (high frequency or high risk).
Exclusion criteria: see above.
Patient characteristics: age: mean 69 years (10 years); sex: 61% female; some patients with existing heart disease (28% had structural heart disease);
TLoC history: median 6 syncopal episodes (range 4–10)
Comorbidities: not stated. Other details: unexplained syncope
Other study comments: significance of positive ATP test unclear. 7 of 15 “control” patients had arrhythmia during TLOC and 2 had no rhythm variations
Index test: Reveal; patient activated; time: mean 18 (9) months; 1st syncopal event analysed; follow up every 3 months to maximum of 36 months (n=36)
Other comparator tests: “control group” of 15 patients tilt and ATP test negative (exclude as too few patients).
for Target Condition/Outcome: events recorded were AV block; sinus arrest; sinus bradycardia (less than 40 bpm); sinus rhythm; sinus tachycardia; AF; ectopic atrial tachycardia; bradycardia; long ventricular pause; but not prespecified which were counted as arrhythmia
Krahn 1998
case series; study held in Canada.
Setting: Cardiology.

Funding: Ontario Heart and Stroke Foundation
TLoC population: patients with a history of recurrent syncope but 12-lead ECG normal. Prior tests: All patients had at least 1 prior test.
ambulatory or in-hospital monitoring, tilt table and EPS negative in all patients

Definition of TLoC: syncope of unknown cause.
Inclusion criteria: syncope of unknown cause; ambulatory or in-hospital monitoring, tilt table and EPS negative.
Exclusion criteria: none.
Patient characteristics: age: mean 58.8 years (17.1); sex: 71% male; some patients with existing heart disease (46% had heart disease);
TLoC history: mean 7.2 (5.4) previous episodes in 2 years
Comorbidities: not stated. Other details: see below
Other study comments: case series no comparator
Index test: ILR (Medtronic); patient activated; time: up to 12 months; mean 4.6 (3.8) months; device explanted if diagnosis made or no event in 2 years (battery life) (n=24)
for Target Condition/Outcome: symptom/rhythm correlation or exclusion of arrhythmia: found: bradycardia; bradytachy; AV block; sinus arrest; SVT; VT (not prespecified)
Krahn 2002
case series; study held in Multinational.
Setting: Hospital several departments. multinational.
Funding: Ontario Heart and Stroke Foundation
TLoC population: patients with a history of recurrent syncope but 12-lead ECG normal. Prior tests: All patients had at least 1 prior test.
syncope of unknown origin; pts had had ECG, Holter or telemetry; some had tilt testing and/or EPS
Definition of TLoC: recurrent syncope or syncope associated with injury.
Inclusion criteria: recurrent syncope or syncope associated with injury.
Exclusion criteria: none.
Patient characteristics: age: mean age 57 years (18); sex: 57% male; some patients with existing heart disease (33% had structural heart disease);
TLoC history: median number of previous episodes 4
Comorbidities: not stated. Other details: see below
Other study comments: case series no comparator; some of these patients included in Krahn 1995 (n=24) or Krahn 1999 (n=81)
Index test: Reveal; patient activated; time: mean 93 (107) days; follow up every 1–2 months for at least 6 months or stop after event (n=206)
for Target Condition/Outcome: symptom-rhythm correlation: prespecified: bradycardia below 50bpm; tachycardia above 150bpm
Moya 2001
case series; study held in Multinational.
Setting: Hospital several departments. multinational.
Funding: not stated
TLoC population: patients with a history of recurrent syncope but 12-lead ECG normal. Prior tests: All patients had at least 1 prior test.
normal ECG, tilt test negative
Definition of TLoC: syncope of uncertain origin.
Inclusion criteria: no significant structural heart disease; 3 or more episodes in last 2 years; interval of 6 months or more between 1st & last episode; history, examination, ECG, carotid sinus massage, echo, 24-hour ECG not diagnostic; tilt test negative.
Exclusion criteria: none.
Patient characteristics: age: mean 63 (17) years; sex: 55% male; some patients with existing heart disease (32% had heart disease);
TLoC history: 3 or more episodes in last 2 years
Comorbidities: not stated. Other details: see below
Other study comments: case series no comparator; tilt test negative patients i.e. unexplained after secondary tests
Index test: Reveal; patient activated; time: mean 9 (5) months; seen every 3 months until diagnosis, battery ran down or end of study (maximum 36 months) (n=82)
for Target Condition/Outcome: ECG/syncope: findings (not prespecified): asystole; brady below 40bpm; AV block
Nierop 2000
case series; study held in The Netherlands.
Setting: Cardiology.

Funding: not stated
TLoC population: patients with a history of recurrent syncope but 12-lead ECG normal. Prior tests: All patients had at least 1 prior test.
history, examination, ECG, echo, routine lab tests 24 hour ECG, assessment of left ventricular ejection fraction, BP
Definition of TLoC: syncope=temporary and reversible LoC.
Inclusion criteria: 2 or more witnessed episodes of syncope of unknown origin in previous 12 months or 1 episode with significant trauma; able to handle activator.
Exclusion criteria: prior MI, ejection fraction <0.40, dilated/hypertrophic cardiomyopathy, nonsustained VT (Holter), aortic valve disease, LVO obstruction, orthostatic hypotension, vasavagal syncope, hypersensitive carotid sinus; >80 yr using >3 cardioactive drugs; dementia.
Patient characteristics: age: mean age 65 (17) years (range 29 to 87 years); sex: 57% female; some patients with existing heart disease (9% had heart disease);
TLoC history: mean event rate in prior 12 months was 5.2 +/−3.2 months (median 4 months, range 1–13 months)
Comorbidities: not stated. Other details: see below
Other study comments: case series no comparator
Index test: Reveal; patient activated; time: 11 (8) months; seen every 3 months (n=35)
for Target Condition/Outcome: symptom-rhythm correlation: findings (not prespecified): bradycardia below 40bpm; asystole over 3s; tachycardia 180–220bpm
Seidl 2000
case series; study held in multinational.
Setting: Hospital several departments. multinational.
Funding: not stated
TLoC population: patients with a history of recurrent syncope but 12-lead ECG normal. Prior tests: All patients had at least 1 prior test.
unexplained syncope and negative laboratory investigations (e.g. ECG, Holter, echo, tilt table, EPS, external loop recorder but not all patients had all of these)

Definition of TLoC: sudden transient loss of consciousness with spontaneous recovery without resuscitative measures.
Inclusion criteria: unexplained syncope (sudden TLOC with spontaneous recovery without resuscitative measures) and negative investigations.
Exclusion criteria: none.
Patient characteristics: age: mean age 56 years; sex: 50% male; some patients with existing heart disease (40% had heart disease); TLoC history: mean 6.3 episodes in previous 12 months; mean duration 5.7 (8.9) years.
Comorbidities: not stated.
Other study comments: case series no comparator
Index test: Reveal; patient activated; time: mean 10.8 (4.3) months; device implanted until syncope/presyncope or patient or investigator wanted to remove it (n=133)
for Target Condition/Outcome: recorded (not prespecified): brady below 50bpm; AV nodal re-entry tachycardia; SVT; torsades de pointes; frequent ventricular premature beats; mixed brady + venticular premature beats + nonsustained VT

From: Appendix D1, Included studies characteristics

Cover of Transient Loss of Consciousness (‘Blackouts’) Management in Adults and Young People
Transient Loss of Consciousness (‘Blackouts’) Management in Adults and Young People [Internet].
NICE Clinical Guidelines, No. 109.
National Clinical Guideline Centre for Acute and Chronic Conditions (UK).
Copyright © National Clinical Guideline Centre for Acute and Chronic Conditions, 2010.

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