Background STEMI knowledge check : Evidence-based Ignorance
I think , It is unfortunate, In the management of STEMI , the two popular strategies of myocardial reperfusion is made to fight with each other as if they are perennial enemies for over two decades. Suddenly, someone with a rare coronary insight thought, why fight each other , they can have a friendly hug and work together. That brought the concept of pharmco -Invasive approach or strategy(PIA) backed up by STREAM, FAST-MI, and TRANSFER AMI studies.Yes, it appears to work well and devoid of all the early adverse events of pPCI. (Much to the dismay of ardent fans of Primary PCI )
*May I add one more shocker of a fact . Deep subset data mining from the above trials did show very early lysis may even act as a perfect stand-alone therapy negating the need for acutely one pharmaco Invasive PCI altogether.(Which was never published) Don’t get alarmed the concept is nothing but , the good old lysis , followed by leisure & elective Ischemia guided PCI in all uncomplicated STEMI.
Now coming to the FAQ in Cardiology Boards: Why is the time window for PIA is 3 to 24 hrs ?
The simple answer for an uncomplicated fellow is “published studies have shown benefit only in this time window. If you do PCI early (,<3h) after lysis paradoxically both bleeding and pro-thrombotic complication over the stented lesions are more common. The upper limit is 24 hrs , since by that time we lose all the potential for myocardial salvage”
– End-
Larger version of the answer
(Advanced readers who are willing to get confused, may read further)
1. Lysis and immediate PCI doesn’t go well at least in trial world. (FINESSE study, by Ellis et all NEJM 2008) Though cardiologists tend to blame lysis (effect of) to Interfere with their hand skills, it can very well be the opposite. The PCI undo the true benefit of lysis. For cardiologists to accrue maximum benefit in the early time window, they need to be too fast, in the process, they accelerate and fuse adverse events of both modalities.
2. The time window 3 to 24h could simply be evidence-based empiricism. In the major STREAM trial, invasive limb happened between 6 and 16 hours only. We stretched both in the top and bottom in the time clock and made it 3 to 24 hours with other trial data.
3. One realistic reason could be this. It requires a minimum of three hours for a patient to reach a place of coronary Invasion after lysis. So one may argue its time allowance for transport .It comes in handy at times.
4 .If the patient reaches earlier, we need to delay the PCI intentionally to please the evidence based medicine. Mind you, every minute delay increases the chance of no reflow as the microvasculature goes for edematous and porous death.
5. Please note, the time window for pharmaco Invasive strategy will go for a tail spin if the initial lysis is failed. Here, we have to rush I guess. Mind you, In this situation, the evidence based blaming that early PCI increases the adverse events immediately following lysis goes topsy turvy . This is where , we should recall old studies of routine rescue PCI (without clinical criteria) rarely succeeded to correct failed thrombolysis (SWIFT trial)
6.Now, why not PCI after 24hrs? The game can be played reversed if you document ongoing Ischemia in IRA or Non IRA, one may do it . The problem arises when the flawed thought process of a cardiologist could legally justify all PCI beyond 24 h /class 3 Indication after STEMI.The argument goes like this. I think this patient has residual silent Ischemia in- spite of severe LV dysfunction (Suspicion is the justification, to which ,unfortunately no one can dispute) It only suggests open artery hypothesis is still trying to raise from the graveyard more than a decade after its near burial.
Final message
To all those energetic, evidence-based cardiac physicians, we all know coronary care is all about time. In fact, we need to be blessed much more than a sense of time. There is something called medically( or spontaneously )stabilized ACS. Please realise , “timely and safe intervention” for your patients could simply mean either playing the time button slow/ fast / slow or fast forward / pause or simply shutdown the cath lab, reach home early and enjoy some music or movie in your favorite streaming player.
Reference
2. Armstrong PW, Gershlick AH, Goldstein STREAM Investigative Team Fibrinolysis or primary PCI in ST-segment elevation myocardial infarction. N Engl J Med. 2013;368(15):1379–1387. [PubMed]
3. Danchin N, Puymirat E, Steg PG, T, on behalf of the FAST-MI 2005 investigators Five-year survival in patients with ST-segment-elevation myocardial infarction according to modalities of reperfusion therapy: the French Registry on Acute ST-Elevation and Non-ST-Elevation Myocardial Infarction (FAST-MI) 2005 Circulation. 2014;129(16):1629–1636. [PubMed]
Dr.S.Venkatesan MD 
