Clinical Outcomes Following Left Main PCI for Acute MI With Cardiogenic Shock

Left main (LM) percutaneous coronary intervention (PCI) among patients with acute myocardial infarction complicated by cardiogenic shock (CS) is associated with higher mortality according to study findings published in The American Journal of Cardiology.

In-hospital mortality ranges from 40% to 50% among patients with acute myocardial infarction (AMI) complicated by CS, which occurs in about 5% to 15% of this patient population. Investigators sought to assess procedural success and in-hospital mortality in patients with CS after AMI treated with LM PCI.

They conducted an observational study that included 2348 consecutive patients with AMI and CS treated with PCI on an intention-to-treat basis in 51 German hospitals between 2010 and 2015. Patient data were from the prospective Arbeitsgemeinschaft Leitende Kardiologische Krankenhausärzte-PCI registry. The investigators performed a multivariate regression analysis for independent predictors of in-hospital mortality that included all parameters with a P value of less than 0.1 in the univariate analysis, as well as diabetes, LM PCI, triple vessel disease, sex, age, and renal insufficiency. They included all patients receiving PCI on an intention-to-treat basis. They compared continuous variables by Mann-Whitney-Wilcoxon test and significance was given to P values less than 0.05.

Patients were divided by PCI type into the following 4 groups:

• LM (n=295 [15 for protected, 280 for unprotected]; 80.1% hypertension; 70.7% hyperlipidemia; 39.6% diabetes)
• 1-vessel (n=491; 70.0% hypertension; 56.2% hyperlipidemia; 19.3% diabetes)
• 2-vessel (n=524; 78.5% hypertension; 67.9% hyperlipidemia; 30.7% diabetes)
• 3-vessel (n=1038; 80.3% hypertension; 70.0% hyperlipidemia; 40.0% diabetes)

Additional patient characteristics that varied between groups were the following:

• LM (age, 70.5±11.8 years; 26.1% women; 61.8% current smokers; 50.5% left ventricular ejection fraction [LVEF] of <40%)
• 1-vessel (age, 63.0±14.2 years; 34.0% women; 63.2% current smokers; 35.8% LVEF of <40%)
• 2-vessel (age, 67.9±12.1 years; 27.9% women; 58.4% current smokers; 40.0% LVEF of <40%)
• 3-vessel (age, 69.9±11.5 years; 29.4% women; 57.0% current smokers; 51.7% LVEF of <40%)

The investigators noted no between-group difference in the periprocedural period with antithrombotic therapy, and no differences in the use of glycoprotein IIb/IIIa, ticagrelor, clopidogrel, or aspirin. Prasugrel was used less in the LM group. There was a significant difference between the affected vessels in the initial thrombolysis in myocardial infarction (TIMI) flow grade of 0 to 1, which was less frequent in the LM group. There were no between-group differences in bleeding complications, stroke, or nonfatal MI. There was increasing extent of coronary artery disease and an increase in usage of an intra-aortic balloon pump, especially in the LM group.

The investigators found that thrombolysis in myocardial infarction 3 patency of the culprit lesion after PCI was 84.6% in the LM PCI group, 84.3% in the 1-vessel PCI group, 84.0% in the 2-vessel PCI group, and 80.8% in the 3-vessel PCI group. In-hospital mortality after PCI was 55.9% in the LM PCI group, 27.9% in the 1-vessel PCI group, 33.9% in the 2-vessel PCI group, and 46.5% in the 3-vessel PCI group. There were no between-group differences in the low bleeding rates (2.0%-2.3%).

LM PCI, TIMI flow of less than 3 after PCI, and higher age were independent predictors of mortality in multivariate analysis.

Study limitations include the lack of wide-spread availability of multiple forms of mechanical circulatory support therapies.

“…LM PCI occurs in approximately 12% of patients with CS and is associated with higher mortality in comparison to other lesion locations,” the investigators wrote. “PCI success rates are high, and these findings, therefore, support the use of PCI in patients with LM-AMI complicated by CS.”