Non-invasive methods can help identify patients at risk of fatal arrhythmias. Ambulatory ECG monitoring provides continuous cardiac rhythm monitoring over extended periods and is useful for evaluating arrhythmias, pacemaker function, and response to antiarrhythmic drugs. Transient VT on ambulatory ECG monitoring is the single best marker of high risk for sudden death in patients with hypertrophic cardiomyopathy. Non-invasive approaches include analyzing heart rate variation, late potentials, QT dispersion, and QRS fragmentation.

1. NON INVASIVE EVALUATION OF
ARRHYTHMIAS - I
Dr D SUNIL REDDY

2. THE EVALUATION …
• There is a constant clinical interest for non-
invasive identification of patients at risk of fatal
arrhythmias.
• Variety of methods have been developed for this
purpose.
• Most of these tests have a good negative
predictive value with a lesser positive predictive
accuracy .

3. METHODS
1. Electrocardiography
2. Ambulatory electrocardiography ( HOLTER )
3. Event recorder
4. Head up tilt table test
5. Exercise testing
6. Signal-Averaged Electrocardiography
7. Spectral analysis (TWA)
8. Imaging etc

4. ELECTROCARDIOGRAPHY
• An ECG taken during the episode of arrhythmia
may be diagnostic in itself , obviating the need for
further diagnostic testing
• An ECG involves measuring electric potentials
from very few points on the body surface far
away from the heart.
• These measurements lack sensitivity (may fail to
detect abnormal activity) and specificity (may fail
to accurately classify the arrhythmia or
determine its location)

5. SOME ECG ABNORMALITIES IN RESTING RHYTHM THAT
SUGGEST ARRHYTHMIA POTENTIAL ( V1 LEAD )

6. HOLTER MONITORING
1. Ambulatory ( Holter ) electrocardiography ( ECG ) is
a widely used noninvasive test to evaluate cardiac
rhythm abnormalities
2. It has also been used for assessing pacemaker and
ICD function, ischemia, and heart rate variability.
3. The clinical utility of the ambulatory ECG recording
lies in its ability to continuously examine the
patient's cardiac rhythm over an extended period of
time during normal routine activity, including any
physical and psychological changes.

7. • Ambulatory ECG recorders may be of two types
• The ones that use magnetic tape recording and
those that use electronic storage system.The
analytical system is the same in both the types.
• The conventional 3 channel Holter recorder is a
small, battery operated, electromagnetic tape
recorder that records 3 channels of
electrocardiographic data on cassette or micro-
cassette magnetic tape.
• More recent developments of digital technology
have led to the ambulatory ECG disk recorder
with 200MB of storage

8. RATIONALE OF HOLTER
• The electrical genesis of cardiac arrhythmias
commonly requires three important components:
1. Cardiac substrate – structural abnormality
2. Electrical triggers – PVC s , NSVT , Bradycardia
3. Physiologic or pathophysiologic modulating factors
which may alter the stability of the cardiac substrate
or the frequency of the triggers.
• These modulating factors are usually transient and
often brief, and include ischemia, electrolyte
imbalance, pH changes, changes in ANS tone and
drugs.

10. ELECTRODE PLACEMENT
E (Brown) Level of 5th intercostal space,
midsternum
A (Black) Same level as E and I , LEFT MAL
S (Red) Top of sternum (manubrium)
I (White) Same level as E and A , RIGHT MAL
Ground
(Green)
Center of sternum or any convenient
location

11. HOLTER LEAD PLACEMENT

12. CHANNEL DESCRIPTION
Channel 1 E(+) to S(-) Similar to MC V1
Anterior view of the heart
Channel 2 A(+) to S(-) Similar to MC V6
Lateral view of the heart
Useful for ST measurements
Channel 3 A (+) to I(-) Similar to inferior lead AVF
Suitable for ST measurements

13. CLASS I INDICATION
1. Patients with unexplained syncope, near-syncope, or
episodic dizziness in whom the cause is not obvious
2. Patients with unexplained recurrent palpitation
3. To assess antiarrhythmic drug response in individuals
in whom baseline frequency of arrhythmia has been
characterized as reproducible and of sufficient
frequency to permit analysis
• To detect proarrhythmic responses to antiarrhythmic
therapy in patients at high risk ( CLASS II a )

14. CLASS III INDICATION
1. Patients in whom cause have been identified by
history, physical examination, or laboratory tests
2. Pts with CVA , without other evidence of arrhythmia
3. Patients who have sustained myocardial contusion
4. Systemic hypertensive patients with LV hypertrophy
5. Post-MI patients with normal LV function
6. Preoperative evaluation of patients for noncardiac Sx
7. Patients with sleep apnea or valvular heart disease
8. Diabetic subjects to evaluate for diabetic neuropathy
9. Patients with rhythm disturbances that preclude HRV
analysis (e.g., atrial fibrillation)

15. 1. If arrhythmic events are sufficiently frequent then a
24 hour Holter is most useful.
2. If the events are episodic and not frequent, a Trans
telephonic event recorder is better suited for
recording the rhythm.
3. Some symptoms are so fleeting that they do not
permit patient to apply electrodes / there is
insufficient time to capture the arrhythmia. In those
instances, the continuous loop trans telephonic
recorder is indicated.
4. In patients whose symptoms include syncope the use
of implantable loop event recorder is indicated.

16. IMPLANTABLE LOOP RECORDER
• The implantable loop recorder or insertable loop
recorder (ILR) is a subcutaneous monitoring device
for the detection of cardiac arrhythmias
• Such a device is typically implanted in the left
pectoral region and stores events when the device is
activated automatically according to programmed
criteria or manually with magnet application

17. • This device can be useful in the evaluation of
palpitations or syncope of undetermined etiology,
particularly when symptoms are infrequent (eg,
less than once per month)
• In such patients, conventional noninvasive testing
is often negative or inconclusive
• Among patients with neurocardiogenic syncope,
an ILR may more accurately establish a causative
relationship between bradyarrhythmias and
syncope than provocative tests (eg, upright tilt
table testing )

18. PARAMETERS ANALYSED BY HOLTER
HEART RATE DATA TOTAL , MIN , AVG , MAX HR
HEART RATE VARIABILITY ASDNN , SDANN 5 ,SDNN , RMSSD
QT ANALYSIS QT AND QTC ( MIN, AVG, MAX )
ST EPISODE ANALYSIS ST LEVEL ( MIN, MAX )
PACER ANALYSIS SINUS, PACED, AP , VP
VENTRICULAR ECTOPY TOTAL , VT RUNS ,TRIPLETS , COUPLETS,
BI / TRIGEMINY
SUPRAVENTRICULAR
ECTOPY
TOTAL , ATRIAL RUNS , BI / TRIGEMINY,
LONGEST RR
ATRIAL FIBRILLATION BEATS,DURATION AND NO. OF EVENTS

19. HEART RATE VARIABILTY
• The most commonly used measures of HRV are
– ASDNN, the standard deviation of all normal
to-normal RR intervals
– SDANN 5, the standard deviation of all five-
minute average RR intervals
– pNN50, the proportion of beats varying by
more than 50 milliseconds from the preceding
QRS and
– rMSSD, the square root of the squares of
successive differences between the RR intervals

20. • During Holter monitoring
1. Sinus bradycardia with heart rates of 35 to 40 bpm
2. Sinus arrhythmia with pauses exceeding 3 seconds
3. Sinoatrial exit block
4. Type I (Wenckebach) 2o AV block (often during sleep)
5. Wandering atrial pacemaker
6. Junctional escape complexes and
7. Premature atrial complexes (PACs) and PVCs can be
observed and are not necessarily abnormal

21. EVALUATION OF THE PATIENT WITH
UNEXPLAINED SYNCOPE
• Ambulatory monitoring, in conjunction with
clinical and electrocardiographic findings, can
be a useful component of the evaluation of
the patient with unexplained syncope.
• Ambulatory monitoring can also be used to
determine which patients with unexplained
syncope will benefit from electrophysiologic
studies .

22. ELECTROCARDIOGRAPHIC MONITORING FOR SYNCOPE
Indications CL LOE
ECG monitoring is indicated in patients who have clinical or ECG
features suggesting arrhythmic syncope
I B
• Immediate in-hospital monitoring (in bed or telemetric) is indicated in
high risk patients
I C
• Holter monitoring is indicated in patients who have very frequent
syncope or pre-syncope (≥one per week)
I B
• ILR is indicated in:
- An early phase of evaluation in patients with recurrent syncope of
uncertain origin, absence of high risk criteria, and a high likelihood of
recurrence within battery longevity of the device
I B
- High risk patients in whom a comprehensive evaluation did not
demonstrate a cause of syncope or lead to a specific treatment
I B
• ILR should be considered to assess the contribution of bradycardia
before embarking on cardiac pacing in patients with suspected or
certain reflex syncope presenting with frequent or traumatic syncopal
episodes
IIa B
• External loop recorders should be considered in patients who have an
inter-symptom interval ≤four weeks
IIa B

23. 1. Bachinsky et al assessed the importance of six clinical
predictors in 141 patients with unexplained syncope who were
referred for EPS
• The following findings were noted:
– Organic heart disease and NSVT were highly sensitive
markers for the presence of serious ventricular
tachyarrhythmias at EPS (sensitivity 100%).
– Sinus bradycardia, first-degree heart block, or BBB by ECG
were sensitive for bradyarrhythmic outcomes (sensitivity 79
percent).
2. Pts without these clinical predictors were almost no risk for a
serious ventricular arrhythmia, at only very slight risk of a
bradyarrhythmia, and therefore unlikely to benefit from EPS
@ Bachinsky WB, Linzer M, Weld L, Estes NA 3rd. Usefulness of clinical characteristics in
predicting the outcome of EP studies in unexplained syncope. Am J Cardiol 1992; 69:1044.

24. CORONARY HEART DISEASE
• The Coronary Drug Project @ and a number of other
trials called attention to the prognostic value of
frequent and complex ventricular arrhythmias in
identifying post myocardial infarction patients at
increased risk of death, including sudden death
• Men with complex ventricular arrhythmia had
– a two-fold increased risk of death from all causes
– a three-fold increased risk of sudden death.
@ Prognostic importance of premature beats following myocardial infarction.
Experience in the coronary drug project. JAMA 1983; 223:1116

25. • Men with ventricular tachycardia had a mortality
that was four to five times greater than men without
ventricular arrhythmias
• Ventricular arrhythmias had an independent
prognostic risk that was additive to the increased risk
of an adverse outcome associated with decreased
left ventricular function
• Ambulatory ECG studies in postmyocardial infarction
patients have also shown that the absence of heart
rate variability, as measured by the standard
deviation of the RR intervals in sinus rhythm, was a
powerful predictor of prognosis, independent of
ventricular arrhythmias or left ventricular function

26. CARDIOMYOPATHY
• Ambulatory electrocardiography in patients with
hypertrophic cardiomyopathy has found that
approximately two-thirds of patients have frequent
and complex ventricular arrhythmias.
• Ventricular tachycardia is present in approximately
25 percent of such patients, and predicts the
subsequent occurrence of sudden death
@ Maron BJ, Savage DD, Wolfson JK, Epstein SE. Prognostic significance of 24 hour
ambulatory electrocardiographic monitoring in patients with hypertrophic
cardiomyopathy: a prospective study. Am J Cardiol 1981; 48:252.

27. • Complex and frequent ventricular arrhythmias
are also detected by ambulatory ECG in 80 to
90 percent of patients with ischemic or
nonischemic dilated cardiomyopathy
• The presence of repetitive ventricular
arrhythmias is an independent predictor of
sudden death in ischemic or nonischemic
dilated cardiomyopathy independent of
hemodynamic or neuroendocrine variables.
@ Holmes J, Kubo SH, Cody RJ, Kligfield P. Arrhythmias in ischemic and
nonischemic dilated cardiomyopathy: prediction of mortality by ambulatory
electrocardiography. Am J Cardiol 2002; 55:146

28. APPARENTLY HEALTHY SUBJECTS
• Ventricular arrhythmias are found in 40 to 75 % of
normal persons assessed by 24 to 48 hours of
continuous ambulatory electrocardiography
• Furthermore, frequent and complex forms have been
found in 1 to 4 percent of the general population .
• The incidence and frequency of ventricular ectopy
increase with age but these findings have no impact
on long term prognosis in apparently healthy subjects.
• This favorable outlook is true even in the presence of
asymptomatic coronary disease.
@ Bjerregaard P. Premature beats in healthy subjects 40-79 years of age. Eur Heart J
1999; 3:493.

29. ANTIARRHYTHMIC DRUG THERAPY
• The variability of ventricular arrhythmia appears to be
time dependent, and more prominent in patients with
low-density ventricular arrhythmias, coronary disease, or
frequent runs of ventricular tachycardia
• The 24 to 48 hour ambulatory ECG examination is the
mainstay of evaluations used in studies examining
suppression of asymptomatic arrhythmias.
• The criteria that demonstrate antiarrhythmic efficacy are
suppression by 70 to 90 percent of mean frequency of
total ventricular ectopy, and total elimination of all
repetitive forms.

30. • Resuscitated SCD pts have a high recurrence rate
of malignant ventricular arrhythmias, and a
decreased long-term survival when they are
untreated or are treated empirically .
• Antiarrhythmic therapy that abolishes repetitive
ventricular activity, as assessed by ambulatory ECG
(in conjunction with exercise testing), predicts
long-term survival in such patients
• Transtelephonic monitoring has also been used to
evaluate antiarrhythmic therapy and has been
extended to provide surveillance of specific high-
risk subgroups

31. ESVEM trial ( NEJM 1993)
• EP Study versus ECG Monitoring (ESVEM) Trial results
were as follows
1. Ambulatory ECG testing resulted in a greater no. of pts
for whom a drug was predicted to be effective, and it
took less time and was less costly.
2. After a six year follow-up, the predictive accuracy of
ambulatory ECG was equivalent to EPS; total, cardiac
and sudden death mortalities were equivalent, and any
form of arrhythmia recurrence was identical.
3. These results confirmed findings that noninvasive
methods of ambulatory ECG and exercise testing were
as effective as (and more cost-effective than) other
methods for managing pts with ventricular arrhythmias.

32. EVALUATION OF PACEMAKERS
• Ambulatory electrocardiography has proved to be valuable
for assessing pacemaker function during long-term FU .
• The use of ambulatory electrocardiography has increased
the diagnosis of pacemaker malfunction by examining the
patient over 24 hours or more during daily activities
• Furthermore, enhanced detection of pacemaker
dysfunction by ambulatory electrocardiography in the early
postimplant period has allowed therapeutic intervention
prior to discharge @
• Holter technology is also an important aid in the visual
interpretation of electrocardiograms from dual chamber
and biventricular pacemakers.
@Janosik DL, Redd RM, Buckingham TA, et al. Utility of ambulatory electrocardiography in
detecting pacemaker dysfunction in the early postimplantation period. Am J Cardiol 2000, 60:1030.

33. THANK YOU

38. CONDUCTION DELAY CONDUCTION BLOCKNO CONDUCTION DELAY

39. • The main approaches for non-invasive arrhythmia
evaluation can be divided into three categories
1. The function of the autonomic nervous system is
studied in heart rate variation analysis
2. The activation discontinuities during the ventricular
depolarization – studied in late potentials and in
spectral turbulence analysis
3. The heterogeneity during the repolarization of the
ventricles is studied in QT dispersion analysis

40. • transient VT on AmbulatoryECG
monitoring is the singlebest
• marker of high risk for sudden
deathin patients with HCM.
• 4. The use of AmbulatoryECG
monitoring to guide selection
• of antiarrhythmic drugsto prevent
recurrent ventricular
• tachycardia or cardiac arrestremains
controversial

41. FRAGMENTATION ANALYSIS
• The propensity for ventricular tachycardias can
also be sought by detecting intra-QRS changes.
• The fragmentation of each QRS complex is
characterized by the number of the extrema (M)
and the product of M and the sum of scaled
amplitude differences between the neighboring
extrema, called fragmentation Index
• Intra QRS changes can also be analyzed by
analyzing the discontinuities in frequency content
of the signal which are analyzed.

42. REPOLARIZATION ANALYSIS
• Heterogeneity of the ventricular repolarization
is also an indicator of vulnerability for
malignant arrhythmias.
• The heterogeneity is studied by analyzing
– the dispersion of the time from the onset of the Q
wave to the apex or the end of the T-wave (QT
time) and
– the duration of the terminal part of the T-wave
( T apex – T end)

43. • If the patient is being evaluated for syncope or
presyncope, extending the period of
monitoring can increase the incidence of
symptomatic events to approximately 50
percent at three days and 75 percent at 5 to
21 days (mean 9 days)