Despite advances in medical technology and invasive management, in-hospital mortality rates for patients with acute myocardial infarction complicated by cardiogenic shock (CS-AMI) continue to increase, according to an analysis of the Cath-PCI Registry, published in JACC: Cardiovascular Interventions.

Researchers evaluated 56 497 patients with AMI who underwent percutaneous coronary intervention (PCI) in the setting of CS. The Cath-PCI registry contains data on patient and hospital characteristics, clinical presentation, treatments, and PCI outcomes from more than 1000 sites in the United States. Patients underwent PCI between January 2005 and December 2013 for CS-AMI.

The primary outcome was to determine temporal trends of demographics, clinical characteristics, management strategies, and in-hospital results of patients undergoing PCI for CS. The study’s secondary outcome was to assess adjusted associations between clinical variables and in-hospital mortality.


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From 2011 to 2013, patients who underwent PCI for CS-AMI increased to 26 940 compared with 5658 in 2005 to 2006. Patients in those later years were more likely to have diabetes, hypertension, dyslipidemia, previous PCI procedures, dialysis, and were less likely to have tobacco abuse, chronic lung disease, renal dysfunction, peripheral vascular disease, heart failure within 2 weeks, and family history of premature coronary artery disease (P for trend <.01).

Teaching institutions have a seen a decline in exposure to such complex cases: from 49.4% in 2005 to 2006 vs 42.3% in 2011 to 2013. Approximately 43% of the national volume of cases was directed to centers with an annual PCI volume of <500 per year (low volume center) compared to 22% in centers with an annual PCI volume of >1000 per year.

In 2011 to 2013, the percentage of patients with symptom onset to time of admission <6 hours significantly decreased for both NSTEMI patients (non-ST segment elevation myocardial infarction; 75% to 58%; P<.01) and STEMI patients (ST-segment elevation myocardial infarction; 88% to 77%; P<.01).

Thrombolytic use has significantly decreased within STEMI patients (4% to 1.2%; P<.01) and intra-aortic balloon pump usage has also decreased (49.5% in 2005 to 2006 vs 44.9% in 2011 to 2013). In 2005 to 2006, 31.5% of patients had more than 1 lesion treated, but this decreased to 25.8% in 2011 to 2013 (P<.01).

PCI was delayed in 35% of STEMI patients due to either cardiac arrest or failure to intubate. In 2011 to 2013, drug eluting stent use declined (46% in 2011 to 2013 vs 65% in 2005 to 2006). However, bare metal stents increased from 21% to 39% (P<.01). Finally, multi-lesion PCI has also declined from 31.5% to 25.7% (P<.01).

Renal failure, bleeding within 72 hours, and rates of red cell transfusion all decreased significantly during the study period. Successful PCI procedures increased, but did not rise above 85% of cases. In-hospital mortality continued to climb from 27.6% in 2005 to 2006 to 30.6% in 2011 to 2013 (P<.01). Cardiac catheterization laboratory deaths made up about one-fifth of these deaths and increased from 15.6% in 2005 to 2006 to 19.9% in 2011 to 2013.

Overall, researchers found that “despite increased adoption of prompt revascularization, in-hospital mortality continues to rise significantly in patients who undergo PCI for CS-AMI patients.”

This is the first study to examine this specific patient population (CS-AMI undergoing PCI); therefore, more research is needed to better understand the pathophysiology and potential pharmacological and mechanical efforts to improve clinical outcomes.

Reference

Wayangankar S, Bangalore S, McCoy LA, et al. Temporal trends and outcomes of patients undergoing PCI for cardiogenic shock in the setting of acute myocardial infarction: a report from the CathPCI Registry. JACC Cardiovasc Interv. 2016. doi:10.1016/j.jcin.2015.10.039.