24 hour holter's role in acute stroke study. Determining the cost benefit, time benefit analysis in Urban tertiary health care set up.

1. Yield of 24 hour Holter in detecting Atrial
Fibrillation in Ischaemic CVA & TIA patients
Dr. Kaushik Sen
MD, DM (H.O.D & Senior Consultant Neurologist, Medica Super
Speciality Hospital)
Dr. Biswarup Banerjee
DPH, DIH, DMCW
(Registrar, Neurology, Medica Super speciality Hospital)

2. PROLOGUE
Cardiac embolism causes approximately 20% of all ischemic strokes
and is disproportionately more disabling than non embolic-stroke,
due to occlusion of larger intracranial arteries and larger ischemic
brain volume.
Atrial fibrillation (AF) remains the most common cause of cardio
embolic stroke (and we restricted ourselves from other causes of CES
in this study)
However anti-coagulation is far superior to anti-platelet therapy in
terms of ischemic stroke prevention. But to initiate anti coagulation
therapy we must document the occurrence of atrial fibrillation/
flutter

3. OBJECTIVE
• Value and cost effective analysis of Routine 24 hour Holter
Monitoring for the Detection of Paroxysmal Atrial Fibrillation in
Patients With Cerebral Ischemic Events.
• Background and purpose: Holter monitoring for the detection of
paroxysmal atrial fibrillation (PAF) is a routine procedure after
cerebral ischemic events, although its yield has not been studied in
details. The aim of this audit was to evaluate the incidence of PAF
and its impact on drug treatment modifications (DTM) in our
sample population and it’s cost effectiveness.

4. METHODS , MATERIALS & INCLUSION CRITERIA
• Even a single run / episode of AF / atrial flutter in 24 hour Holter is clinically
significant to start oral anticoagulation in Ischemic CVA / TIA patients.
• If any AF/ flutter was diagnosed, detailed analysis of medical charts (eg,
regarding initiation of anticoagulation) was done.
• Regular supraventricular bursts (suggestive of AV nodal reentrant or ectopic
atrial tachycardias) were not qualified as PAF.
• DTM was defined as initiation of oral anticoagulation (OAC or NOAC) or switch
from aspirin/clopidogrel to OAC or NOAC.
• Comparisons between groups will be performed by use of both subjective (in
percentage) objective (calculated P value) (detailed later)

5. EXCLUSIONS
• Known pre diagnosed patients with atrial fibrillation and flutter.
• Patients already on OAC/NOAC because of valvular heart disease/ valve
replacement etc.
• Patients with ischaemic stroke/ TIA who are already on anticoagulation therapy
for other non cardiac systemic issues like DVT.

6. SAMPLING & DURATION
• 100 outdoor/indoor patients with cerebral ischemic events (CIEs; complete
strokes or transient ischemic attacks) who had undergone 24 hour Holter for
risk stratification were included in this retrospective study (observation time,
1st March 2021 to 28th February 2022).
• Cluster (dividing the population into subgroups, but each subgroup should have
similar characteristics to the whole sample) sampling technique was used and
for simplicity it was multistaged.
• Group A- 50 CIE patients with clinically suspected cardio- embolic events
(having 1 or more of the followings)
1.Acute infarcts in multiple arterial territories
2.Infarcts in typical arterial territories like PICA, SCA, top of the basilar artery,
posterior division of MCA
3.Large cortical based lesions with or without haemorrhagic transformation
4.Any markers of likely acute cardiac issues like raised Trop I / anti Pro BNP

7. • Group B- 50 CIE patients with no clinical suspicion of CES
Now 24 hour Holter monitoring records of the entire sample population (100) will
be analysed.
1. a = number of detected PAF in 24 hour holter in group A
b = number of detected PAF WITHOUT Holter ( detected during transthoracic
ECHO, 12 lead standard ECG, telemetry during hospital stay)
So despite strong clinical suspicion no PAF is detected in 50 - (a + b) in group A
2. x = number of detected PAF in 24 hour Holter in group B
y = number of detected PAF WITHOUT Holter ( same way in group B expecting
this number to be very small )
No PAF is detected in 50 – ( x + y ) in group B

8. TARGETS
• In group A ( strong clinical suspicion of CES)- 30% (15 out of 50
patients to have AF in Holter)
• In group B ( no clinical suspicion of CES)- 5% (5 out of 50)

9. Group A + B 24 hour Holter detected PAF 24 hour Holter did not detect PAF
50 a 50 – ( a + b )
50 x 50 – ( x + y )

10. • To keep things simple, we can proceed to calculate the percentage values of
occurrence ( here AF in Holter ) or non occurrence in separate groups
• For group A occurrence = a / 50 x 100 non occurrence = {50 – (a + b )}/50 x 100
• For group B occurrence = x/ 50 x 100 non occurrence = {50 – (x + y)}/ 50 x 100
• For group A + B occurrence = ( a + x ) % non occurrence= {100 –(a+b+x+y)}x 100
Here we must pre determine what percentage of yield (occurrence of AF) in
individual groups (or both together) will be considered SUBJECTIVELY significant.

11. • However we can interpret our findings in a much more objective
way.
• Comparisons between groups can easily be performed by use of 1-
way analysis of variance for continuous variables that are described
as mean±SD. A value of P<0.05 will be considered statistically
significant. Statistical analysis will be done with IBM-SPSS V28.0.1
• Either way ( percentage or calculated P value) if there is a
significance in any or both the groups (subjective or objective) we
can continue 24 hour Holter monitoring in all patients ( as defined
for sampling) of cerebral ischemic events.
• If we can not establish any significance in any or both groups, we
have to plan other strategies like longer (48/72 hours) Holter/ event
recorders etc.

12. THANK YOU ALL