The Pit and the Pendulum
revised 2012
with apologies to Mr. Poe
Carl F. McComas, M.D.
October 26, 2012
The Pit and the Pendulum
Edgar Allan Poe, 1842
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Prisoner is tortured in pitch dark room
Rats eat his food, but he learns to lure rats to
the leather straps confining him
Razor sharp pendulum swings slowly, inching
closer to chest of prisoner
After rats free him, pendulum retreats
Walls began to close in on prisoner
As he is about to fall into pit, walls retreat and
he is grabbed into safety
The Pit and the Pendulum
Edgar Allan Poe, 1842
Thesis is effect of fear
Patent Foramen Ovale and Stroke
Intuitional Assumptions
• Venous thrombi can gain access to left
atrium through PFO
• Closure of PFO prevents future related
strokes
Patent Foramen Ovale and Stroke
Intuitional Assumptions
• Venous thrombi can gain access to left
atrium through PFO
– Must be a source of venous thrombi
– PFO must be of sufficient nature to allow right
to left flow of thrombi
Patent Foramen Ovale and Stroke
Intuitional Assumptions
• Closure of PFO prevents future related
strokes
– Natural history unclear; may be uncommon
cause
– Procedural related complications, including
stroke are not inconsequential
– Closure device may serve as source of emboli
Patent Foramen Ovale and Stroke
• Typically of greater significance in younger
patients without other identifiable risk
factors for stroke, ‘Cryptogenic Stroke
(CS)’
• Autopsy and echo studies suggest 25 %
incidence
• Incidence perhaps 40 to 50 % in CS patients
Patent Foramen Ovale and Stroke
Incidental or Pathologic
• In general, 1/3 are likely not causally related
• Younger patient has greater relationship
• Absence of other common risk factors increases
causal relationship
• Echo findings which increase causal relationship
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Size
Atrial septal aneurysm
Greater right to left shunt
Higher septal wall mobility
Patent Foramen Ovale and Stroke
Closure and Secondary Prevention
CLOSURE I
• Randomized trial of CS patients
– STARFlex closure + clopidogrel + aspirin
– Warfarin
– Warfarin + aspirin
– Aspirin
Patent Foramen Ovale and Stroke
Closure and Secondary Prevention
CLOSURE I
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STARFlex closure group
Overall stroke risk in 2 years ~ 3 %
Increased risk of atrial fibrillation
Causes of stroke other than PFO identified
Patent Foramen Ovale and Stroke
Closure and Secondary Prevention
CLOSURE I
• Medicine treated group
• Overall stroke risk in 2 years ~ 3 %
• Causes of stroke other than PFO identified
Patent Foramen Ovale and Stroke
Closure and Secondary Prevention
CLOSURE I
• Wrong patients
• Wrong device
• Wrong outcome assumptions
Patent Foramen Ovale and Stroke
Closure and Secondary Prevention
CLOSURE I
• Wrong patients
– Included patients with events called TIAs
– Included patients without acute ischemic events
on imaging studies
– Likely included patients with migraines,
seizures, and other mechanisms
– Included patients with lacunes
Patent Foramen Ovale and Stroke
Closure and Secondary Prevention
CLOSURE I
• Wrong closure device
– Used STARflex occluder
– Higher periprocedural complications, including
atrial fibrillation, than Amplatzer and Gore
Helex devices
Patent Foramen Ovale and Stroke
Closure and Secondary Prevention
CLOSURE I
• Wrong outcome assumptions
– Size of studies
• Small numbers
– Duration of study
• PFO related ischemic events tend to occur over
decades; study length was 2 years
Patent Foramen Ovale and Stroke
The Fear Factor
• Fear on part of patients
– Fear of ‘hole in heart’
– Fear of implanted device
• Fear on part of physicians
– Eagerness to follow intuition
– Lack of desire to just treat medically
Patent Foramen Ovale and Stroke
Further Thoughts
• ‘and earnest endeavor to comprehend my
true state’
– Edgar Allan Poe, The Pit and the Pendulum
• Future trial considerations
– Use better device
– Better patient selection
– Longer duration of trial