Sustaining a STEMI may be a pathological end point for coronary artery disease. But , from the management point of view it is actually a starting point for CAD evaluation .Strategies to prevent further cardiac events must be formulated .
How do you manage a asymptomatic un-complicated post STEMI patient* at discharge ?
- Do a sub- maximal symptom limited EST and then discharge.
- Advised to come back after 2 months for a stress test or Perfusion imaging
- Continue with intensive medical management without EST or CAG and monitor only the symptoms
- Advice coronary angiogram in all and decide depending upon the lesions (Pre -discharge CAG )
- I am a modern day cardiologist . This question does not arise . . . as I do only primary angioplasty for all my cases !
( *Please note , this forms the bulk of STEMI population (up to 60 % )
Answer : Your guess is the correct answer!
Why we need to risk stratify STEMI at discharge ?
The morality and outcome in STEMI though appears to be a continuously falling curve , the slope is not linear.
The classical mortality till discharge is about 6-8 %. Between discharge and 3oth day there is 1-2 % additional mortality
At end of first year there is further 2 % mortality. From second year onwards there is an annual attrition rate up to 3 %.
The aim of doing a pre-discharge EST is to do identify ” patient subset ” who are destined to die within 30 days of STEMI. If you schedule the EST after 6-8 weeks one can not prevent these two deaths out of 100 !
( Of course , we assume a prompt revascularisation in those vulnerable would prevent this !). By doing so , we can avoid the bulk of unnecessary PCIs that happen with routine CAG following STEMI.
Pre discharge EST can be done safely within 5-7 days with a symptom limited test (70 % of THR or up to HR of 120 /mt ) This simple test if it is negative can virtually R/O a critical proximal lesion with near 100% sensitivity.
Should we risk stratify patients who have undergone pPCI as well ?
Most of us would love to believe , once pPCI is done to the patient , he reaches a therapeutic end point. But it is not the truth . It is the degree of LV dysfunction , extent of contrary coronary lesion , co existing risk factors and the intensity of medical treatment only would determine the long term outcome.
It is very important to realise the pPCI is aimed at opening the IRA and other lesions are often left alone. So never believe pPCI per se would confer total risk reduction following a STEMI . There is considerable evidence to suggest the opposite may be true at least in high high risk pPCI ,where metals are placed in complex , vulnerable thrombotic milieu. Hence it seems logical to risk stratify all patients after primary PCI (In fact, this population require more vigilance ) .
When will you advice an EST following pPCI ?
It is usually not needed in the immediate discharge phase in single vessel disease which would have been tackled during pPCI.In multi-vessel CAD , where only the IRA was tackled during pPCI ,the same guidelines that of thromolysed STEMI shall apply .Since we know the coronary anatomy already , EST helps us to evaluate the hemodynamic status of non IRA lesions if there are any . While , this is a logical debate , logics has a rare place in medicine . It is ironical , stress test is rarely done even after 6months following pPCI in most centers.
It is a pity , anatomical risk stratification has squarely beaten the scheme of physiological risk stratification in most cardiology centers . A pre -discharge EST* was a good concept that gave us an idea about the coronary reserve after the ACS. It was a collective wisdom of cardiologists that has hanged this useful concept. It is still more shocking , to note even the scheduled 6 week EST is dropped from the post MI work up in some institutions.
* Many would consider ordering an early EST in STEMI is an act of bravery ! The fear seems to be genuine and most will agree with that. But , please remember a physiological test (Cheapest and simple is EST or a Nuclear perfusion ) should precede CAG in all asymptomatic post STEMI population whenever possible . If EST could not be done prior to CAG for some reason , at least do it following the CAG . It will have an important impact on the downstream decision making which is often an inappropriate PCI !