Prediction and prevention of sudden cardiac death after STEMI

1. SCD after STEMI-
Prediction & Prevention

2. Introduction
• Sudden cardiac death is one of the causes of death in
a patient of myocardial infarction
• In observational studies the incidence of SCD after
MI has ranged from 2% to 4%
• In the VALIANT trial, SCD rate was found to be
1.4%/month in the first 30 days, which decreased
exponentially over time

3. Time periods after MI
• On the basis of literature, we can consider 3 distinct time periods
after MI: Early (≥48 hours–40 days), subacute (41 days–6 months),
and remote (>6 months to many years)
• Current data suggests the following:
• First 48 hrs: Life threatening VAs that occur during the first 24–48 h
of ACS do not imply the risk for SCD over time
• Early Phase (also called as ‘48-h and 40-day Rule’): most
controversial as data not clear whether ICD implantation is
beneficial or not
• Subacute & Remote Phase: ACC/AHA/ESC & HRS guidelines state
that ICDs should be implanted for the primary prevention of SCD in
patients at least 40 days after MI, with an EF of 30–40% and NYHA
class II–III, who are on optimal pharmacotherapy and have a
reasonable expectation of survival, with a good functional status for
at least 1 year (Class 1, Level of Evidence A)

4. Risk Factors
• Reduced LV ejection fraction (LVEF) or history of heart failure
• Ventricular tachycardia (VT) induced by electrophysiologic
study (EPS)
• Spontaneous ventricular premature beats (VPBs) and
nonsustained ventricular tachycardia (NSVT) documented on
24hour ambulatory monitoring
• Late potentials on a signal averaged ECG (SAECG)
• Reduced heart rate variability (HRV) assessed by ambulatory
monitoring
• T wave (repolarization) alternans (TWA)
Sustained arrhythmias that occur in the early postMI phase (usually
defined as the first 48 hours) are generally considered epiphenomena of
the MI and are not consistently associated with long term prognosis

5. ICD Studies in the Early Phase of MI
• Both DINAMIT & IRIS showed fewer SCD deaths
• However, an increase in non-arrythmic deaths and non-significant
benefit of ICD implantation in the early phase of MI was observed

6. • The BEST multicenter investigation comprised 143 survivors of
acute MI and patients were stratified to a conventional strategy
or Electrophysiology Pacing Study (EPS) – a guided strategy for
ICD implantation
• In the follow-up of 2 years, a trend towards lower mortality in
the EPS-guided/ICD arm was observed in comparison with the
conventional arm: 20 versus 29.5%, respectively

8. Study details
• In this study by Zaman et al in STEMI patients, EF was
assessed for more than 2 days of coronary intervention
• If EF> 40% : Patients discharged
• If EF< 40%: EPS was done
• No inducible patients were discharged and those with
inducible monomorphic ventricular tachycardia lasting more
than 10 s had ICDs implanted before discharge.
• At the median of 12 months of followup, the mortality rate
in all subgroups was low: 3, 3 and 6%, respectively.
• This suggests that early ICD implantation limited to patients
with inducible ventricular tachycardia results in low mortality
in the population treated with coronary intervention due to
Stelevation MI

9. Possible Reasons for discrepancy between
SCD susceptibility in the early phase of MI
& the lack of benefit from ICD therapy
• ICD shock therapies (adequate and inappropriate)
lead to a two or threefold increase in total mortality,
respectively, probably due to heart failure
progression over longterm followup
• Right ventricular pacing has a detrimental effect
• 'Inappropriate' protocols are followed, with regard to
inclusion criteria (too high cutoff value of ejection
fraction in patients qualifying for ICD therapy).

10. Optimizing ICD therapy
It can be done by:
• Implantation of dual chamber ICDs, which seem to be superior to
single chamber ICDs.
• Reprogramming of the device settings (enhanced programming).
• Programming ventricular tachycardia or fibrillation at longer
detection intervals (i.e., number of intervals detected: 30/40).
• Applying ventricular tachycardia or fibrillation detection zones at
higher rates (i.e., fast ventricular tachycardia up to 250 bpm).
• Introducing new technological tools (i.e., enabling the monitoring of
the patients' fluid status).

11. Future ICD perspectives in post-MI
patients
• Better selection of high risk MI survivors using the microvolt
T-wave alternans and electrophysiological pacing studies
• Biventricular cardioverter defibrillator in the early phase of MI
to prevent both heart failure progression and SCD episodes.
• Blood pressure monitoring detector to deliver shock therapy
in hemodynamically unstable patients only.
• Wearable cardioverter defibrillators.
• Miniature, portable, easily attached and removable
automated external defibrillators for the crucial '48h and
40day‘ period

12. Does EPS play a role in stratification?
• Objective: The purpose of this study was to evaluate
outcomes of electrophysiology (EP)-
guided defibrillatorimplantation early after ST-elevation MI in
patients with ejection fraction ≤40%
• Methods: EP study was performed 9 days after MI (n = 360).
Predischarge defibrillator was recommended if VT with cycle
length ≥200 ms was induced with ≤4 extrastimuli (EP-positive
[EP(pos)], n = 142). EP-negative (EP(neg)) patients were
discharged without a defibrillator
• Primary Endpoint: Either sudden death or spontaneous
ventricular arrhythmia
Kumar S et al. Heart Rhythm. 2010 Nov;7(11):1589-97

13. Results
71
6
Defibrillator implantation (in % of
patients) as per study groups
EP Positive
EP Negative

14. Incidence of primary endpoint at 2
years
0
5
10
15
20
25
Category 1 Category 2
Primary endpoint
Category 1
Category 2
22%
4.3%
p=0.035

15. Lack of a defibrillator in EP positive patients conferred them
with a 4 fold increased risk of sudden death (p=0.014)
EP(neg) patients without a defibrillator were at significantly
lower risk for the primary endpoint than were EP(pos)
patients without a defibrillator (adjusted HR 0.34, P = .011).
Short inducible VT cycle length (200-230 ms) and use of the
fourth extrastimulus identified patients at significant
arrhythmic risk.

16. Conclusions
• EP study performed early after MI identified
patients at significant long-term arrhythmic
risk at a critical time after MI in
whom defibrillator implantation was
protective
• EP testing might be a promising means of risk
stratification in early post-MI patients

17. Current Recommendations of major
societies

18. Conclusions
• With regard to primary prevention of sudden cardiac
death (SCD), the most important initial parameter is
left ventricular ejection fraction (LVEF)
• LV function should be assessed in the time period
when an ICD may be indicated (ie, after 40 days). If a
low LVEF was documented earlier, it should be
reassessed at this time.
http://www.uptodate.com/contents/incidence-of-and-risk-stratification-for-sudden-
cardiac-death-after-acute-myocardial-infarction

19. Further risk stratification is largely based upon the LVEF:
• No further risk stratification is required for patients in whom an ICD
is indicated for primary prevention of SCD: those with an LVEF ≤30
percent (MADIT II criteria) or those who satisfy SCD-HEFT criteria
(ischemic cardiomyopathy, LVEF ≤35 percent, NYHA II or III HF)
• For patients with an LVEF >40 percent, we recommend no further
risk stratification, since such patients are unlikely to meet
indications for an ICD
• For patients with an LVEF of 31 to 40 percent, we do not routinely
proceed with further risk stratification. However, periodic Holter
monitoring (once or twice a year) is a reasonable approach, with
the understanding that patients found to have nonsustained
ventricular tachycardia should be referred for invasive
electrophysiology (EP) study
http://www.uptodate.com/contents/incidence-of-and-risk-stratification-for-sudden-
cardiac-death-after-acute-myocardial-infarction

20. References
• Sredniawa B et al. Early therapy following myocardial infarction:
arguments for and against implantable cardioverter-defibrillators. Future
Cardiol. 2010;6(3):315323
• Zaman S, Kovoor P. Sudden cardiac death early after myocardial infarction:
pathogenesis, risk stratification, and primary prevention. Circulation. 2014
Jun 10;129(23):2426-35
• Estes NA 3rd. The challenge of predicting and preventing sudden cardiac
death immediately after myocardial infarction. Circulation. 2009 Jul
21;120(3):185-7
• Podrid PJ et al. Incidence of and risk stratification for sudden cardiac death
after acute myocardial infarction. Accessed from:
http://www.uptodate.com/contents/incidence-of-and-risk-stratification-
for-sudden-cardiac-death-after-acute-myocardial-infarction