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Obesity is associated with higher mortality in patients with cardiogenic shock
International Journal of Cardiology 117 (2007) 278 – 279 www.elsevier.com/locate/ijcard
Letter to the Editor
Obesity is associated with higher mortality in patients with cardiogenic shock Paari Dominic Swaminathan, Monica Stancu, Prasannakumar Venkatesh, Sandeep Khosla, Rohit R. Arora⁎ Division of Cardiovascular Diseases, Department of Medicine, Chicago Medical School at Rosalind Franklin University of Medicine and Science, United States Received 30 January 2006; accepted 26 May 2006 Available online 7 August 2006
Abstract Cardiogenic shock is the leading cause of death in patients with acute myocardial infarction. Studies that have focused on identifying mortality predictors in patients with cardiogenic shock have not evaluated outcomes in obese patients. A study of sixty-one patients with cardiogenic shock demonstrated that obese patients with cardiogenic shock have a higher mortality risk compared to non-obese patients. © 2006 Elsevier Ireland Ltd. All rights reserved. Keywords: Myocardial infarction; Shock; Obesity
Cardiogenic shock (CS) is the leading cause of death in patients hospitalized with acute myocardial infarction with the mortality of patients with cardiogenic shock remaining high between 50% and 60% [1], despite advances in therapy. Given the magnitude of this problem intense efforts have focused on identifying patients at risk and mortality predictors. However, there is a paucity of studies evaluating the outcome in obese patients with cardiogenic shock. Therefore we investigated the relationship between body mass index (BMI) and mortality in patients with cardiogenic shock. Sixty-one consecutive patients with AMI (STEMI and non-STEMI) complicated by CS in a single institution over a five year period were evaluated. Patients were classified by body mass index (BMI) into obese (BMI ≥ 30, n = 24), or non-obese (BMI b 30, n = 37). The primary endpoint (in-hospital cardiovascular mortality) and secondary endpoints (length of hospitalization and re-hospitalization) were compared between the two groups. Differences in ⁎ Corresponding author. Chicago Medical School – NCVAMC, 3001, Green Bay Road, North Chicago, IL 60064, United States. Tel.: +1 2246104503; fax: +1 224 610 3878. E-mail address: [email protected] (R.R. Arora). 0167-5273/$ - see front matter © 2006 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2006.05.039
continuous variables were analyzed by ANOVA and categorical variables by Fisher's Exact Test. The baseline variables were similar between the two groups. About 33% (8/24) of obese patients with CS died in hospital compared to only 3% (1/37) of non-obese (p = 0.002). There were no significant differences between obese and non-obese groups in the length of hospital stay and re-hospitalization rates. The results of the study demonstrate that obese patients with CS secondary to acute myocardial infarction have a higher mortality risk during their hospital stay than their nonobese counterparts. Within the obese patients there was a trend for those who died to have higher BMI than those who survived, although the results were not statistically significant. Obesity has variable impact on the cardiovascular system and can cause hemodynamic overload, higher left ventricular mass, poor systolic function, greater impairment of left ventricular diastolic filling and defects in neuroendocrine pathways [2,3]. Despite these effects there is considerable evidence in medical literature that obesity may have a protective effect in patients with chronic heart failure [4]. Our findings, which do not show a similar protective effect but rather shows a deleterious effect, may be explained by the differences in the causation of mortality in cardiogenic
P.D. Swaminathan et al. / International Journal of Cardiology 117 (2007) 278–279
shock and chronic heart failure. Cardiogenic shock is an acute process involving pump failure causing myocardial and systemic hypo-perfusion, with compensatory physiological mechanisms which spiral out into a vicious cycle causing multiple organ dysfunction. Cardiac Power (product of cardiac index and mean arterial pressure) is a hemodynamic measure that strongly correlates with mortality in patients with cardiogenic shock [5]. Patients with lower cardiac power index were found to have higher mortality rates. As cardiac index in this equation, has cardiac output as the numerator and BMI as the denominator, patients with higher BMI values could have lower cardiac index and therefore lower cardiac power. This could explain our finding that obese patients with cardiogenic shock have higher mortality rates. Prospective studies with bigger sample size are needed to validate these observations.
279
References [1] Hochman JS, Buller CE, Sleeper LA, et al. Cardiogenic shock complicating acute myocardial infarction—etiologies, management and outcome: a report from the SHOCK Trial Registry. SHould we emergently revascularize Occluded Coronaries for cardiogenic shocK? J Am Coll Cardiol 2000;36(3 Suppl A):1063–70. [2] Alexander JK, Dennis EW, Smith WG, Mad KH, Duncan WC, Austin RC. Blood volume, cardiac output, and distribution of systemic blood flow in extreme obesity. Cardiovasc Res Cent Bull 1962;1:39–44. [3] Alpert MA. Obesity cardiomyopathy: pathophysiology and evolution of the clinical syndrome. Am J Med Sci 2001;321(4):225–36. [4] Horwich TB, Fonarow GC, Hamilton MA, MacLellan WR, Woo MA, Tillisch JH. The relationship between obesity and mortality in patients with heart failure. J Am Coll Cardiol 2001;38(3):789–95. [5] Fincke R, Hochman JS, Lowe AM, et al. Cardiac power is the strongest hemodynamic correlate of mortality in cardiogenic shock: a report from the SHOCK trial registry. J Am Coll Cardiol 2004;44(2):340–8.
Letter to the Editor
Obesity is associated with higher mortality in patients with cardiogenic shock Paari Dominic Swaminathan, Monica Stancu, Prasannakumar Venkatesh, Sandeep Khosla, Rohit R. Arora⁎ Division of Cardiovascular Diseases, Department of Medicine, Chicago Medical School at Rosalind Franklin University of Medicine and Science, United States Received 30 January 2006; accepted 26 May 2006 Available online 7 August 2006
Abstract Cardiogenic shock is the leading cause of death in patients with acute myocardial infarction. Studies that have focused on identifying mortality predictors in patients with cardiogenic shock have not evaluated outcomes in obese patients. A study of sixty-one patients with cardiogenic shock demonstrated that obese patients with cardiogenic shock have a higher mortality risk compared to non-obese patients. © 2006 Elsevier Ireland Ltd. All rights reserved. Keywords: Myocardial infarction; Shock; Obesity
Cardiogenic shock (CS) is the leading cause of death in patients hospitalized with acute myocardial infarction with the mortality of patients with cardiogenic shock remaining high between 50% and 60% [1], despite advances in therapy. Given the magnitude of this problem intense efforts have focused on identifying patients at risk and mortality predictors. However, there is a paucity of studies evaluating the outcome in obese patients with cardiogenic shock. Therefore we investigated the relationship between body mass index (BMI) and mortality in patients with cardiogenic shock. Sixty-one consecutive patients with AMI (STEMI and non-STEMI) complicated by CS in a single institution over a five year period were evaluated. Patients were classified by body mass index (BMI) into obese (BMI ≥ 30, n = 24), or non-obese (BMI b 30, n = 37). The primary endpoint (in-hospital cardiovascular mortality) and secondary endpoints (length of hospitalization and re-hospitalization) were compared between the two groups. Differences in ⁎ Corresponding author. Chicago Medical School – NCVAMC, 3001, Green Bay Road, North Chicago, IL 60064, United States. Tel.: +1 2246104503; fax: +1 224 610 3878. E-mail address: [email protected] (R.R. Arora). 0167-5273/$ - see front matter © 2006 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2006.05.039
continuous variables were analyzed by ANOVA and categorical variables by Fisher's Exact Test. The baseline variables were similar between the two groups. About 33% (8/24) of obese patients with CS died in hospital compared to only 3% (1/37) of non-obese (p = 0.002). There were no significant differences between obese and non-obese groups in the length of hospital stay and re-hospitalization rates. The results of the study demonstrate that obese patients with CS secondary to acute myocardial infarction have a higher mortality risk during their hospital stay than their nonobese counterparts. Within the obese patients there was a trend for those who died to have higher BMI than those who survived, although the results were not statistically significant. Obesity has variable impact on the cardiovascular system and can cause hemodynamic overload, higher left ventricular mass, poor systolic function, greater impairment of left ventricular diastolic filling and defects in neuroendocrine pathways [2,3]. Despite these effects there is considerable evidence in medical literature that obesity may have a protective effect in patients with chronic heart failure [4]. Our findings, which do not show a similar protective effect but rather shows a deleterious effect, may be explained by the differences in the causation of mortality in cardiogenic
P.D. Swaminathan et al. / International Journal of Cardiology 117 (2007) 278–279
shock and chronic heart failure. Cardiogenic shock is an acute process involving pump failure causing myocardial and systemic hypo-perfusion, with compensatory physiological mechanisms which spiral out into a vicious cycle causing multiple organ dysfunction. Cardiac Power (product of cardiac index and mean arterial pressure) is a hemodynamic measure that strongly correlates with mortality in patients with cardiogenic shock [5]. Patients with lower cardiac power index were found to have higher mortality rates. As cardiac index in this equation, has cardiac output as the numerator and BMI as the denominator, patients with higher BMI values could have lower cardiac index and therefore lower cardiac power. This could explain our finding that obese patients with cardiogenic shock have higher mortality rates. Prospective studies with bigger sample size are needed to validate these observations.
279
References [1] Hochman JS, Buller CE, Sleeper LA, et al. Cardiogenic shock complicating acute myocardial infarction—etiologies, management and outcome: a report from the SHOCK Trial Registry. SHould we emergently revascularize Occluded Coronaries for cardiogenic shocK? J Am Coll Cardiol 2000;36(3 Suppl A):1063–70. [2] Alexander JK, Dennis EW, Smith WG, Mad KH, Duncan WC, Austin RC. Blood volume, cardiac output, and distribution of systemic blood flow in extreme obesity. Cardiovasc Res Cent Bull 1962;1:39–44. [3] Alpert MA. Obesity cardiomyopathy: pathophysiology and evolution of the clinical syndrome. Am J Med Sci 2001;321(4):225–36. [4] Horwich TB, Fonarow GC, Hamilton MA, MacLellan WR, Woo MA, Tillisch JH. The relationship between obesity and mortality in patients with heart failure. J Am Coll Cardiol 2001;38(3):789–95. [5] Fincke R, Hochman JS, Lowe AM, et al. Cardiac power is the strongest hemodynamic correlate of mortality in cardiogenic shock: a report from the SHOCK trial registry. J Am Coll Cardiol 2004;44(2):340–8.