Abstract
Aim
To assess the impact on in-hospital and long-term survival of thrombus aspiration (TA) during primary percutaneous coronary intervention (PPCI) for ST-segment elevation myocardial infarction (STEMI) complicated by cardiogenic shock (CS).
Methods and Results
From September 2001 to May 2010 we collected data from 155 patients affected with STEMI complicated by CS undergoing PPCI (12.4% of all PPCI) including 70 patients (45.2%) in TA group and 85 patients (54.8%) in conventional PCI group. Patients in TA group were more likely to have right ventricular infarction (24.3% vs 5.9%, p = 0.002), higher mean left ventricular ejection fraction (40% ± 9% vs 35% ± 7%, p < 0.0001) and lower left main coronary artery occlusion (2.8% vs 21.2%, p = 0.002). TA was associated with a lower rate of in-hospital and long-term mortality (31.4% vs 48.2%, p = 0.05 and 42.8% vs 64.7%, p = 0.01 respectively) at a mean follow-up time of 6.1 ± 2.1 years. At multivariate analysis the only independent predictor of in-hospital and long-term survival was the procedural success (HR 0.18 95% CI 0.025–0.31, p = 0.03 and HR 0.46 95% CI 0.09–0.74, p = 0.034 respectively).
Conclusions
In this retrospective study TA, performed during PPCI for STEMI complicated by CS, was not an independent predictor of in-hospital and long-term survival.
1
Introduction
Reperfusion therapy with primary percutaneous coronary intervention (PCI) has become the treatment of choice for patients with ST-segment elevation acute myocardial infarction (STEMI) , but it can be complicated by spontaneous or angioplasty-induced embolization of atherothrombotic material, which is associated with an higher mortality . Cardiogenic shock (CS) is the most important complication of STEMI with a very high mortality rate up to 50%–60% . Manual thrombus aspiration (TA) has been associated to both better myocardial perfusion and improved survival . However, very few data are available on the efficacy of such devices in STEMI complicated by CS, mostly because such patients are generally excluded from clinical trials. In this retrospective study we evaluated the feasibility and the impact on survival of TA in this high-risk population.
2
Methods
We retrospectively reviewed data of all patients with STEMI complicated by CS who underwent PCI between September 2001 and June 2010 in our catheterization laboratory. Demographic, clinical and procedural data were prospectively collected in a dedicated database (Cardioplanet V.3.0.8, Ebit Aet S.p.A., Genoa, Italy). The study protocol was reviewed and approved by the Ethics Committee of our Institution (ASL 103, Piemonte Region, Italy). STEMI was defined as prolonged (≥ 30 min) typical chest pain or symptoms with the presence of at least 0.1 mV ST-segment elevation or new pathologic Q waves in ≥ 2 contiguous electrocardiogram (ECG) leads or new left bundle branch block lasting more than 20 min. CS was defined as systolic blood pressure < 90 mmHg (without inotropic drugs or intra-aortic balloon pump support) secondary to severe ventricular dysfunction and associated with signs of end-organ hypoperfusion (e.g. cold or diaphoretic extremities, altered mental status or anuria). Patients with hypotension related to hypovolemia, transient hypotension related to vasodilatation and bradycardia associated with spontaneous reperfusion were not included in the analysis. All STEMI patients with CS who complained symptoms for ≤ 12 h were immediately transferred to the catheterization laboratory for PCI. The devices used for manual TA were Diver CE (Invatec, Roccandelle, Italy) and Export (Medtronic Inc, Minneapolis, MN). In our center, the indications for manual TA were usually driven by few parameters evaluated after diagnostic angiography as already reported : a) visual estimation of infarct related artery (IRA) diameter ≥ 3 mm; b) the absence of severe proximal tortuosity and/or calcifications; c) complete vessel occlusion with distal convex contrast stain and the presence of visual thrombus in case of a patent IRA. However, the final decision to the use of TA was left to the discretion of the operator as well as the use of abciximab and the intra-aortic balloon pump (IABP) support. All patients were routinely treated with aspirin (325 mg upon arrival, and then 100 mg daily), clopidogrel (loading dose of 300 or 600 mg, and then 75 mg daily) and with intravenous bolus of unfractionated heparin (100 U/kg body weight or 60 U/kg body weight if abciximab was also given). Heparin therapy was stopped after the procedure, but, in case of IABP use, it was continued until its removal. When used, abciximab infusion was continued for 12 h after the procedure. Beta-adrenergic blockers and ACE inhibitors were used as in-hospital standard therapy, if not contraindicated.
A successful procedure was defined as a residual stenosis of treated vessels < 50% associated with a Thrombolysis In Myocardial Infarction (TIMI) 3 grade flow . Before the procedure all patients underwent an echocardiogram to assess left ventricular ejection fraction (LVEF) by Simpson’s rule , and to exclude mechanical complications as a cause of CS (i.e., cardiac tamponade, interventricular septum or LV free wall rupture, acute mitral regurgitation due to papillary muscle rupture).
2.1
Clinical end-points
The primary end points of the study were in-hospital and long-term overall mortality. Furthermore, we also assessed the combined end-points of major adverse clinical events (MACE), including death from any cause, recurrent myocardial infarction (MI), non fatal stroke and target vessel revascularization (TVR). ST-segment resolution (STR) at 60 min after PCI, Stent thrombosis (ST), admission for heart failure, implant of an automatic cardioverter defibrillator (ICD) and major bleedings were also separately evaluated. In-hospital events were derived from clinical records. Clinical follow-up was performed by ambulatory clinical visits or telephone calls. In case of events, clinical records were updated or, if not available, detailed history was acquired from patients or (in case of death) from patients’ relatives or physicians.
Recurrent MI was diagnosed in case of typical chest pain with newly occurring ECG abnormalities and increase of creatine kinase to twice the basal level (after an initial decline in the in-hospital phase); stroke was defined as any focal and nonconvulsive neurological deficit lasting more than 24 h; TVR was defined as repeated PCI or CABG due to restenosis or progression of the disease in the treated vessels. Major bleeding was defined according to the Bleeding Academic Research Consortium classification . ST was defined as definite, probable or possible according to the Academic Research Consortium .
2.2
Statistical analysis
Data are reported as means (with standard deviations) or proportions. Continuous variables were compared by t-test, whereas categorical variables were compared by chi-square test. A multivariate Cox proportional hazard regression was applied to identify independent predictors of in-hospital and long-term mortality. The variables with a p value < 0.1 at univariate analysis were entered into the multivariate model. A p value < 0.05 was always required for statistical significance. Furthermore, parsimonious propensity matched analysis has been performed, considering as covariates the variables reaching statistical significance at univariate analysis. Analyses were performed using the statistical software IBM SPSS Statistics, Version 20 (New York, NY, USA).
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