Cardiogenic Shock Literature Summaries

OVERVIEW

• early revascularisation
• intra-aortic balloon pump

EARLY REVASCULARISATION

Hochman JS, Sleeper LA, Webb JG, Sanborn TA, White HD, Talley JD, Buller CE, Jacobs AK, Slater JN, Col J, McKinlay SM, LeJemtel TH. Early revascularization in acute myocardial infarction complicated by cardiogenic shock. SHOCK Investigators. Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock. N Engl J Med. 1999 Aug 26;341(9):625-34. PMID: 10460813. [Free Fulltext]

• parallel group MC-RCT
• Intention-to-treat analysis
• n = 302
• included patients with cardiogenic shock (clinical and hemodynamic crtieria) and ECG evidence of acute MI
• excluded if not suited to revascularisation, valve disease, DCM or other forms of shock
• emergency revascularisation (PCI or CABG within 12h) vs initial medical stabilisation
  — Median time from randomization to revascularization: 1.4 vs. 102.8 hrs
• Outcomes:
  -> no significant difference in 30-day mortality (primary outcome)
  -> at 6 months emergency revascularisation did have a survival advantage: 50.3% vs. 63.1% mortality (RR 0.80; 95% CI 0.65-0.98; P=0.027
  -> follow-up of the SHOCK trial cohort also demonstrated the benefit or revascularization at 1 and 6 years
• Problems:
  — Subgroup analysis suggested benefit of revascularization was limited to patients <75 years, but subsequent studies found that >75y old patients also get the same benefit.
  — both arms had high rates of IABP insertion (~85%)
  — slightly higher rates of LVAD and cardiac transplantation in intervention group
  — study was powered to detect a 10% mortality difference; underpowered to detect smaller more realistic differences
• Bottom line: patients with acute MI and cardiogenic shock have better longterm mortality if they receive emergency revacularisation

INTRA-AORTIC BALLOON PUMP

Thiele H, et al; IABP-SHOCK II Trial Investigators. Intraaortic balloon support for myocardial infarction with cardiogenic shock. N Engl J Med. 2012 Oct 4;367(14):1287-96. doi: 10.1056/NEJMoa1208410. Epub 2012 Aug 26. PubMed PMID: 22920912.

• open-label, parallel group MC-RCT
• Intention-to-treat analysis
• n = 600
• included patients with acute STEMI or NSTEMI complicated by cardiogenic shock (defined by end-organ perfusion, low BP, catecholamine use) who received optimal medical therapy and early reperfusion (PCI ~95% or CABG ~5%)
• excluded >90y, CPR >30 min, coma, non-MI diagnosis, IABP contra-indicated
• intervention: IABP insertion + standard therapy vs standard therapy
• outcome = 30 day mortality -> no difference; no difference in multiple secondary outcomes either
• problems
  — underpowered: powered to detect a difference of 12% in 30-day survival rates (seems unrealistic), assuming a rate of 56% in the control group
  — more of the controls got LVADs: 3.7% vs. 7.4% (P=0.053)
  — most IABPs went in post-PCI (86%)
  — lower mortality rate (40%) in this trial compared to other registries and RCTs (42-48%) suggests more mild or moderately severe shock cases, precluding generalizability to severe shock.
  — 10% cross-over rate from control group to IABP
  — long-term follow-up results are pending
  — high use of catecholamines and relatively low rate of true hypotension (many had SBP >90 before randomization)
• bottom line: no 30 day mortality benefit from IABP insertion for cardiogenic shock following MI when early revascularisation was planned.

Ranucci M, Castelvecchio S, Biondi A, de Vincentiis C, Ballotta A, Varrica A,Frigiola A, Menicanti L; Surgical and Clinical Outcome Research (SCORE) Group. Arandomized controlled trial of preoperative intra-aortic balloon pump in coronary patients with poor left ventricular function undergoing coronary artery bypass surgery*. Crit Care Med. 2013 Nov;41(11):2476-83. doi:10.1097/CCM.0b013e3182978dfc. PubMed PMID: 23921278.

• prospective SC RCT
•  Patients: LVEF < 0.35, haemodynamically stable, undergoing CABG
• n = 110, randomised to IABP or no IABP
• Results:
  – No difference in major morbidity
  – No difference in secondary outcomes (MV duration, cardiac output, ICU / hospital LOS)
  – Non-signif increase in CI pre-CPB with IABP (associated with an increase in dopamine post CBP in control group that didn’t persist into ICU stay)
  – lower MAP in IABP group
• Commentary and criticisms:
  – Study stopped after second interim analysis due to futility
  – Well matched groups at baseline