Acute Psychological Stress and Susceptibility to Ventricular Arrhythmias

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Acute Psychological Stress and Susceptibility to
Ventricular Arrhythmias
Mustafa Hassan, MD
Cardiology fellow Division of
Cardiology University of Florida,
Gainesville
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Mental Stress and Arrhythmias

• Large body of anecdotal evidence and
  observational studies suggests a relationship
  between acute psychological stress and arrhythmic
  events/sudden cardiac death.
• Psychological stress can lower the threshold for
  induced ventricular arrhythmias and precipitates
  spontaneous arrhythmic events in patient with CAD
  and implantable ICDs. 1
• Mental stress can induce transient myocardial
  ischemia in 30-70 of patient with CAD. 2

• Deanfield et al. Lancet 1984 2 1001-1005
• Lampert et al. Circulation 2000 101158-164

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• It has been estimated that at least 20 of
  episodes of serious ventricular arrhythmias or
  sudden cardiac death are precipitated by intense
  or unusual emotional stress. 1, 2
• The physiologic mechanisms by which these effects
  occur are not clear.

• Reich et al. JAMA. 1981246(3)233-235.
• Myers et al. Br Heart J. 197537(11)1133-1143.

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Hypothesis

• We sought to examine the effect of psychological
  stress of QT dispersion.
• We hypothesized that myocardial ischemia mediates
  the effect of psychological stress on QT
  dispersion

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Stellate Ganglion

• Hypothesis
• Mental stress increases the QTd.
• Ischemia mediates the effect of Psychological
  Stress
• on Arrhythmias

Direct sympathetic effect
QT Dispersion
Sympathetic outflow
Ventricular arrhythmias
Psychological Stress
QT Dispersion
Myocardial Ischemia
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Study Design
70 Patients with documented CAD
First visit Demographic and Psychosocial
Questionnaires
Second Visit Psychological stress testing with
rest/stress
myocardial perfusion imaging
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Mental stress test
EKG, BP and HR Recorded at baseline
Rest for 30 minutes
Fasting overnight Hold BB, CCB and nitrates
Instructions for the speech test read to the
patients
Video tape recording started
2 minutes to prepare their speech
EKG, BP and HR recorded every minute
3 minutes speech
Recovery
EKG, HR and BP recorded at 1, 3, 5 and 10
minutes
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Myocardial Perfusion Imaging

• Same day rest/stress protocol.
• Radioisotope (99m-Tc-sestamibi) was injected at
  one minute into the speech.
• Rest and stress images were compared for number
  and severity of perfusion defects.

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Measurement of QT dispersion

• QT was manually measured by one observer.
• If a U wave was present, the QT interval was
  measured to the nadir between the T and the U
  waves.
• If the T wave could not be clearly defined that
  lead was excluded.
• Only EKGs with gt8 analyzable leads were included.
• QTd The longest minus the shortest QT intervals.
  
• A blinded observer performed a second measurement
  on a randomly selected sample of EKGs (n40).
  Concordance correlation coefficient 0.792.

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Demographics
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Stress response HR, BP and QTd
MSIMI Mental stress-induced myocardial ischemia
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Results cont.
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Results cont.
60.00
40.00
P0.006
Mean increase in QTd from rest to stress (ms)
20.00
0.00
-20.00
Ischemia
No Ischemia
Mental Stress Induced Myocardial Ischemia
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Stress, ischemia and QTd
comparing the stress QTd between MSIMI groups,
controlling for the resting QTd. Controlling for
the resting QTd, CAD severity factors (history of
MI, CABG or PCI), co-morbid medical conditions
(hypertension and diabetes) and cardiac
medications (beta blockers and calcium channel
blockers).
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Conclusion

• Mental stress induces a significant increase in
  QT dispersion.
• This effect seem to be mediated, at least
  partially, by the development of myocardial
  ischemia.
• Further studies are needed to validate these
  findings and explore other mechanisms and
  potential therapeutic interventions.