Impact of smoking on the incidence and survival of cardiogenic shock complicating acute myocardial infarction treated with reperfusion therapy

Abstract

C shock due to predominant left ventricular failure remains the main cause of death among patients with ST-segment elevation acute myocardial infarction (AMI). Identification of baseline characteristics associated with the occurrence and prognosis of cardiogenic shock may help to prevent its development and improve its outcome. • • • Between 1988 and 1998, 1,000 patients were consecutively admitted to our department within 6 hours of the onset of symptoms with ST-segment elevation AMI. All were screened for emergency angiography and reperfusion therapy. AMI was defined by prolonged chest pain consistent with ongoing myocardial ischemia and 1 mm ST-segment elevation in 2 contiguous leads on the admission electrocardiogram. The diagnosis of cardiogenic shock was based on the combination of systolic blood pressure 90 mm Hg despite inotropic support and volume expansion, and symptoms of acute circulatory failure (cyanosis, cold extremities, restlessness, mental confusion, or coma). When necessary, the cardiogenic etiology of shock was confirmed by hemodynamic assessment of the cardiac index ( 2 L·min ·m ) and the pulmonary artery wedge pressure ( 18 mm Hg) using a SwanGanz catheter. In all cases, mechanical complications were excluded by emergency echocardiography. The study was divided into 2 parts: (1) assessment of the baseline variables associated with the development of cardiogenic shock on the whole cohort; (2) assessment of the variables associated with in-hospital mortality among patients who developed cardiogenic shock. In a first step, univariate analysis was performed to test the relations between the criterion of interest (i.e., shock vs no shock, and survival vs death) and the set of potential risk factors. This analysis involved the chi-square test or the Fisher’s exact test for qualitative factors, and the Student’s t test for continuous variables. In a second step, a stepwise logistic regression was performed. Variables with a p value 0.20 in the univariate analysis were included in the model. Goodness of fit of the final model was assessed by the Hosmer and Lemeshow test. Statistical analysis was performed using the SAS statistical package (SAS Inc., Cary, North Carolina). Among the entire cohort, 51 patients (5%) presented with cardiogenic shock on admission. All of them underwent reperfusion therapy. The emergency interventions used are shown in Figure 1. Rescue coronary angioplasty was performed in 4 of 10 patients who were treated with intravenous thrombolysis. Successful reperfusion, defined as Thrombolysis In Myocardial Infarction 3 flow in the infarct-related artery, was achieved in 32 patients (63%), and incomplete reperfusion (Thrombolysis In Myocardial Infarction 2 flow) in 12 patients (23%). In-hospital mortality was 39 of 51 patients (76%) who presented with cardiogenic shock on admission, versus 48 of 949 (5%) among patients who did not present with shock (p 0.001). The main baseline characteristics encountered in patients with and without cardiogenic shock are listed in Table 1. Shock patients were older, had a lower prevalence of hyperlipidemia and smoking, and were more likely to have an anterior AMI and multivessel disease. Table 2 lists the 4 variables found to be significantly associated with the risk of development of cardiogenic shock in multivariate analysis. Hyperlipidemia and smoking had a protective effect with regard to the development of cardiogenic shock, From the Service de Cardiologie A, Hopital Bichat-Claude Bernard, Paris; and INSERM U 436 and Informatique Medicale, Hopital de la Pitie Salpetriere, AP-HP Paris, France. Dr. Himbert’s address is: Service de cardiologie A, Hopital Bichat-Claude Bernard, AP-HP, 46 rue Henri Huchard 75018 Paris, France. E-mail: himbert.dominique@ wanadoo.fr. Manuscript received July 2, 2001; revised manuscript received and accepted August 29, 2001. FIGURE 1. Emergency reperfusion therapy in 51 patients with ST-segment elevation AMI complicated by cardiogenic shock. Light gray section, primary percutaneous transluminal coronary angioplasty; medium gray section, intravenous thrombolysis; small dark gray section, spontaneous reperfusion.