Current guidelines advice us to wait for 40 days following STEMI to implant ICD in most high risk patients.
Why this cool off period.? *
- Essentially we are waiting for the Infarct healing process to be completed.
- By this time electrical stability may be restored. The risk of VT/VF declines per naturalis.
- LV function recovery is possible. As stunned and hibernating myocardium resumes its mechanical function and patient might jump out of the MADIT-2 cutoff point. (EF< 30%)
- Introducing ICD very early after STEMI may be a myocardial irritant and that it self can generate arrhythmias.
- There is a possible interference by the leads in the physiological remodeling process.
Final message
So the cool off period is not only to reduce the unnecessary ICD implantation but also to avoid lead related issues .
* This 40 day rule is based on one large study from Germany. (DINAMIT, 2004 ) . However few believe the rule is not absolute. There can be individual exceptions in high risk patients with critical LV dysfunction .
Other wise . . . How do you digest a death occurring on 35th day in a patient who is waiting for an ICD scheduled one week later ?
Reference
Link to ACC/AHA Guidelines for ICD Implantation 2013
New development
How to bridge the 40 day gap in really high risk post MI patient ?
We can’t keep him in CCU. Here comes the role of WCD (Wearable cardiovertor defibrillator.) Life vest is from Zoll . WCD can act like a bridge till the 40 days when the patient becomes eligible for ICD.
Dr.S.Venkatesan MD 
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