Predictors of mortality in patients with cardiogenic shock treated with primary percutaneous coronary intervention and intra-aortic balloon counterpulsation.

BACKGROUND: Cardiogenic shock remains the most serious complication of patients hospitalized with acute myocardial infarction (AMI). Early revascularization is the cornerstone of invasive therapy, while mechanical support with intra-aortic balloon pump (IABP) is debatable. From our institutional shock registry we sought to determine predictors of in-hospital mortality-including the aspect of IABP timing-and to develop a clinical risk score for shock patients with AMI.
METHODS: From January 2005 till December 2010, 102 patients with cardiogenic shock due to AMI treated with primary percutaneous coronary intervention (PCI) and IABP were analyzed. Univariate and multivariate logistic regression analyses were used to identify independent predictors of in-hospital mortality. Logistic regression analysis and receiver-operating curves were used to generate a mortality risk score.
RESULTS: The mean age of the cohort was 70.1 ± 11.0 years and 70 % were men. One third of patients had a non-ST segment elevation myocardial infarction and 30 % had to be resuscitated before coronary intervention. Mean left ventricular ejection fraction was 25 %. After admission, 23 % of patients developed an acute renal failure and 10 % needed renal dialysis during hospital stay. In 52 % of patients IABP therapy was initiated after primary PCI, while the remaining patients had an IABP-assisted primary PCI. All-cause in-hospital mortality was 40.2 %. Using multivariate analysis, age (odds ratio [OR] 1.08, p = 0.006), resuscitation before PCI (OR 3.46, p = 0.045), vasopressor use (OR 7.88, p = 0.003), acute renal failure (OR 11.18, p = 0.001), and IABP implantation after PCI (OR 4.36, p = 0.011) were independently associated with in-hospital mortality. Based on these predictors, a mortality-risk score was calculated as follows: 1.5 × IABP timing before PCI + 0.1 × age + resuscitation before PCI + 2 × vasopressor use + 2.5 × acute renal failure. Using a cut-off value of 10.4, this score had a specificity of 83 % and a sensitivity of 82 % for prediction of in-hospital death.
CONCLUSIONS: We identified age, vasopressor use, resuscitation before PCI, acute renal failure and IABP implantation after PCI as independent predictors of in-hospital mortality in patients with cardiogenic shock due to AMI. The timing of IABP insertion was the only modifiable factor predicting in-hospital mortality in our cohort. Consequently, balloon pumping should be started before PCI to improve outcome of cardiogenic shock patients.