Brian Locke

#ACS

Learning goals:

  1. Be able to define Terms
  2. Understand two major paradigm shifts in labeling ACS regarding how we identify heart tissue that is going to infarct and how what we know about how injury to myocardium occurs
  3. Understand who benefits from heparinization, revascularization.
  4. Appreciate that we do not have data to support an approach to managing "ACS" in the. ICU.

##Prolog

  • Case 1: septic, in ICU, on pressors. Troponin is 0.5 ng/dl (elevated). No ekg changes, no symptoms, no new WMA on echo. What is this? Myocardial Injury, presumably acute
  • Case 2: a patient who has cardiac risk factors, exertional dyspnea that has progressed to occuring at rest and is relieved a
  • Case 3: a patient with known non-obstructive CAD is sick sick sick in the ICU, troponin is 0.5 ng/dl, new ST-depression, no WMA, troponin peaks at 1.25 ng/dl then downtrends as he gets better / off pressors. His mixed venous saturation is high - probably sepsis. Heparin? Cath? no
  • Lastly: how did the Designation of STEMI start? *Answer: it used to be q-wave MI (or not) because we had no actions to take and so that indicated if the heart died. STE criteria were developed as inclusion for who to get lytics (broad strokes, basically inclusion criteria) to try to identify people who would go on to infarct, so that we could intervene

##Definitions

2018 4th Universal Definition of MI

  • STEMI (ACS with STE on EKG. Note, this is a surrogate for occlusion MI = needs emergent revascularization. However it has ~80% sensitivity and 80% specificity for that. More at OMI Manifesto)
  • NSTEACS (troponin elevation and 1 of: symptoms, ischemic EKG changes, or segmental wall motion abnormalities)
  • Unstable angina (new or changing chest pain attributable to ischemia without troponin elevation after enough time has elapsed that you would see it. With or without EKG changes. Note, stable angina is not ACS)
  • Myocardial injury (troponin elevation, no symptoms, ischemic EKG changes, or segmental wall motion abnormalities)

###Pathophysiology:

  • thrombosis (occlusion)
  • narrowing of artery
  • myocardial damage unrelated to oxygen delivery

Management

####Workup: troponin without ACS? ####Heparin?

####Revascularization

  • ICTUS trial: timing of revasc in NSTEMI. No difference between early and restrictive strategy (though prior studies had shown a difference)