Impact of Body Mass Index on Outcomes After Percutaneous Coronary Intervention in Patients With Acute Myocardial Infarction
2007; Elsevier BV; Volume: 99; Issue: 7 Linguagem: Inglês
10.1016/j.amjcard.2006.11.038
ISSN1879-1913
AutoresLaxmi S. Mehta, William Devlin, Peter A. McCullough, William W. O’Neill, Kimberly A. Skelding, Gregg W. Stone, Judith Boura, Cindy L. Grines,
Tópico(s)Coronary Interventions and Diagnostics
ResumoObesity is a widespread problem, particularly in the cardiovascular disease population. Obese patients have a lower incidence of cardiovascular mortality after elective percutaneous coronary interventions (PCIs); however, there is a paucity of data in the acute myocardial infarction (AMI) setting. This study investigated the effects of body mass index (BMI) on outcomes after percutaneous coronary revascularization in patients with AMI. Patients were categorized into 3 groups based on their BMI, i.e., normal, overweight, or obese. Most patients undergoing primary PCI for AMI (70%) were overweight or obese. Obese patients were significantly younger and more often diabetic, hypertensive, and hyperlipidemic compared with other groups. Angiographically, there was no difference in presence of multivessel disease, final Thrombolysis In Myocardial Infarction grade 3 flow, and presence of thrombus or dissection. Mortality was significantly lower in the hospital at 6 and 12 months in the obese group. Multivariate analysis demonstrated age >70 years, final Thrombolysis In Myocardial Infarction grade 70 years, final Thrombolysis In Myocardial Infarction grade <3 flow, history of peripheral vascular disease, and ejection fraction to be the strongest predictors of mortality at 12 months. In conclusion, our data show that obese patients with AMI have a lower risk for in-hospital, 6-month, and 12-month mortality and cardiovascular events than patients with a normal BMI. Coronary artery disease treatment options have not differed based on body mass index (BMI). Paradoxically, databases of patients undergoing elective percutaneous coronary intervention (PCI) have shown lower incidences of in-hospital and long-term deaths in obese patients compared with their normal-weight counterparts.1Gurm H.S. Whitlow P.L. Kip K.E. BARI InvestigatorsThe impact of body mass index on short- and long-term outcomes in patients undergoing coronary revascularization Insights from the Bypass Angioplasty Revascularization Investigation (BARI).J Am Coll Cardiol. 2002; 39: 834-840Abstract Full Text Full Text PDF PubMed Scopus (188) Google Scholar, 2Powell B.D. Lennon R.J. Lerman A. Bell M.R. Berger P.B. Higano S.T. Holmes Jr, D.R. Rihal C.S. Association of body mass index with outcome after percutaneous coronary intervention.Am J Cardiol. 2003; 91: 472-476Abstract Full Text Full Text PDF PubMed Scopus (91) Google Scholar, 3Gurm H.S. Brennan D.M. Booth J. Tcheng J.E. Lincoff A.M. Topol E.J. Impact of body mass index on outcome after percutaneous coronary intervention (the obesity paradox).Am J Cardiol. 2002; 90: 42-45Abstract Full Text Full Text PDF PubMed Scopus (165) Google Scholar, 4Gruberg L. Weissman N.J. Waksman R. Fuchs S. Deible R. Pinnow E.E. Ahmed L.M. Kent K.M. Pichard A.D. Suddath W.O. Satler L.F. Lindsay Jr, J. The impact of obesity on the short-term and long-term outcomes after percutaneous coronary intervention: the obesity paradox?.J Am Coll Cardiol. 2002; 39: 578-584Abstract Full Text Full Text PDF PubMed Scopus (537) Google Scholar, 5Minutello R.M. Chou E.T. Hong M.K. Bergman G. Parikh M. Iacovone F. Wong S.C. Impact of body mass index on in-hospital outcomes following percutaneous coronary intervention (report from the New York State Angioplasty Registry).Am J Cardiol. 2004; 93: 1229-1232Abstract Full Text Full Text PDF PubMed Scopus (109) Google Scholar However, there is a paucity of data regarding BMI and acute myocardial infarction (AMI) outcomes. Greater body weights in patients with AMI were previously shown to have less efficacy in thrombolytic therapy,6Lundergan C.F. Reiner J.S. McCarthy W.F. Coyne K.S. Califf R.M. Ross A.M. Clinical predictors of early infarct-related artery patency following thrombolytic therapy: importance of body weight, smoking history, infarct-related artery and choice of thrombolytic regimen: the GUSTO-1 experience Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries.J Am Coll Cardiol. 1998; 32: 641-647Abstract Full Text Full Text PDF PubMed Scopus (61) Google Scholar perhaps due to lower administered doses. Our objective was to determine the effect of BMI in the modern era on short- and long-term outcomes after primary PCI in patients with AMI. We identified 2,325 patients with AMI from the Primary Angioplasty in Acute Myocardial Infarction (PAMI) database who underwent PCI. This database consists of several prospective, multicenter, international, randomized trials for the treatment of AMI. The present study group comprised 167 patients from PAMI-1, 882 patients from PAMI-2, and 1,276 patients from Stent PAMI. Details of these trials have been previously described.7Grines C.L. Browne K.F. Marco J. Rothbaum D. Stone G.W. O'Keefe J. Overlie P. Donohue B. Chelliah N. Timmis G.C. et al.Primary Angioplasty in Myocardial Infarction Study GroupA comparison of immediate angioplasty with thrombolytic therapy for acute myocardial infarction.N Engl J Med. 1993; 328: 673-679Crossref PubMed Scopus (1903) Google Scholar, 8Stone G.W. Marsalese D. Brodie B.R. Griffin J.J. Donohue B. Constantini C. Balestrini C. Wharton T. Esente P. Spain M. et al.PAMI-II Trial InvestigatorsA prospective, randomized evaluation of prophylactic intraaortic balloon counterpulsation in high risk patients with acute myocardial infarction treated with primary angioplasty.J Am Coll Cardiol. 1997; 29: 1459-1467Abstract Full Text Full Text PDF PubMed Scopus (258) Google Scholar, 9Grines C.L. Cox D.A. Stone G.W. Garcia E. Mattos L.A. Giambartolomei A. Brodie B.R. Madonna O. Eijgelshoven M. Lansky A.J. O'Neill W.W. Morice M.C. Stent Primary Angioplasty in Myocardial Infarction Study GroupCoronary angioplasty with or without stent implantation for acute myocardial infarction.N Engl J Med. 1999; 341: 1949-1956Crossref PubMed Scopus (897) Google Scholar In this pooled analysis, we included only those patients treated with emergency PCI in whom height and weight data were available for BMI calculation. All patients presented within 12 hours of symptom onset and demonstrated ≥30 minutes of angina or anginal equivalent symptoms. Electrocardiographic diagnostic criteria of an AMI included an ST-segment elevation ≥1 mm in ≥2 contiguous leads or new left bundle branch block. Trials excluded patients previously treated with thrombolytic agents for the index AMI and those with cardiogenic shock, renal failure, and stroke within the previous 1 month, life expectancy <1 year from a noncardiac condition, or women with childbearing potential. All patients were emergently taken to the cardiac catheterization laboratory for coronary angiography and received PCI when it was deemed necessary by the operator. Device selection and anticoagulation regimens were also determined by the study protocols and patients' cardiologists. Contemporary drug regimens after AMI were initiated. Patients were initially monitored in the cardiac intensive care unit and discharged from the hospital when medically stable. Height and weight on the case-report form consisted of direct measurements and self-report according to the clinical scenario. In most hemodynamically unstable patients, the self-reported data were the only available sources of data on height and weight. Clinical, angiographic, and in-hospital outcomes data were prospectively collected by a nurse or research coordinator. Clinical follow-up for long-term outcomes were obtained by telephone contact or doctor office visit at 1 month and 6 and 12 months. Detailed case-report forms were completed and reviewed by independent data monitors. Primary end points of each study were reviewed by a clinical events committee. Cine angiograms were assessed by a core laboratory for coronary anatomy, left ventricular ejection fraction, and angiographic outcomes. Adiposity was determined by BMI, which was calculated as weight in kilograms divided by height squared in meters. Patients were characterized into 3 weight categories based on their BMI. Obesity was classified as a BMI ≥30 kg/m2, overweight as a BMI from 25 to 29.9 kg/m2, and normal BMI (neither obese nor overweight) as a BMI 2 flow and 5); otherwise Fisher's exact test was used. Stepdown multivariate logistic regression analysis was completed on death at 12 months. All variables that were used in the comparison across BMI groups with a p value 70 years, female gender, diabetes mellitus, hypertension, hyperlipidemia, previous peripheral vascular disease, family history of coronary artery disease, current tobacco use, initial Killip class >I, ejection fraction, baseline heart rate >100 beats/min, baseline systolic blood pressure <100 mm Hg, β-blocker usage in the emergency room or catheterization laboratory, door-to-balloon time, initial percent stenosis (increments of 10), final TIMI grade <3 flow, left circumflex or left anterior descending arteries as the infarct-related artery, groin bleeds, and blood transfusions. Statistical analysis was completed using SAS 8.0 (SAS Institute, Carey, North Carolina). A p value <0.05 was considered statistically significant. Data were analyzed in 2,325 patients with AMI who received primary PCI. Obese patients comprised 25% of the group, 45% were overweight, and 30% were of normal weight. Mean BMI in the obese group was 33.9 ± 3.7 kg/m2. Baseline clinical characteristics differed significantly among the 3 groups and are listed in Table 1. Obese patients were younger and less likely to be women, whereas patients with normal BMI were typically older and had a larger percentage of women. Cardiac risk factors, including diabetes mellitus, hypertension, and hyperlipidemia, were more prevalent in the obese group. Normal BMI patients had higher rates of peripheral vascular disease and smoking history compared with the other 2 groups. Obese patients were more likely to receive β-blocker therapy in the emergency room or catheterization laboratory (48% vs 43% vs 35%, p <0.001). Door-to-balloon time was significantly longer in obese patients than in overweight and normal BMI patients (153 vs 143 vs 140 minutes, p = 0.0003). Angiographic details are presented in Table 2.Table 1Baseline clinical characteristicsVariableBMI (kg/m2)p Value<25 (n = 703)25–29.9 (n = 1,039)≥30 (n = 583)Mean BMI (kg/m2)22.8 ± 1.927.3 ± 1.433.9 ± 3.7Age (yrs)63 ± 1360 ± 1257 ± 12 70 yrs32%24%16%<0.0001Women33%21%27%<0.0001Diabetes mellitus11%15%23%<0.0001Hypertension39%45%57% I12.3%12.1%7.2%0.0046 Open table in a new tab Table 2Angiographic dataVariableBMI (kg/m2)p Value<25 (n = 703)25–29.9 (n = 1,039)≥30 (n = 583)Initial TIMI grade flow0.091 065.1%62.2%68.3% 112.1%12.1%9.7% 212.4%15.8%14.5% 310.3%9.9%7.4%Initial percent stenosis98 ± 598 ± 598 ± 40.049Multivessel coronary disease47%45%45%0.70Ejection fraction (%)48 ± 1248 ± 1249 ± 120.55Final TIMI grade flow 02.0%1.7%0.4%0.04 11.6%0.5%0.7% 25.1%5.7%6.1% 391.3%92.2%92.9%0.58Final percent stenosis18 ± 2017 ± 1716 ± 160.23Thrombus11%12%14%0.23Dissection18%17%17%0.72 Open table in a new tab Use of aspirin and angiotensin-converting enzyme inhibitors was similar across groups, but utilization of β-blocker medications remained higher in the obese group than in the overweight and normal BMI groups (66% vs 64% vs 59%, p = 0.024). Short-term outcomes are presented in Table 3. Vascular complications consisting of groin bleeds (7.6% vs 6.8% vs 11%, p = 0.014) were higher in the normal BMI group, and they, in turn, had a higher incidence of blood transfusions (6.9% vs 6.3% vs 9.7%, p = 0.031). Reinfarction, ischemic target vessel revascularization, and disabling stroke rates were similar in all 3 groups. In-hospital mortality was higher and length of hospital stay was longer in the normal BMI group despite similar procedural success.Table 3In-hospital outcomesVariableBMI (kg/m2)p Value<25 (n = 703)25–29.9 (n = 1,039)≥30 (n = 583)Pulmonary edema2.8%3.5%4.8%0.25Sustained hypotension4.6%5.3%4.5%0.78Groin bleed11%6.8%7.6%0.014Renal failure requiring dialysis0.2%0.9%0.7%0.33Disabling stroke0.4%0.1%0.5%0.26Ventricular tachycardia or fibrillation5.7%4.8%3.4%0.19Coronary artery bypass5.3%4.0%3.4%0.22Reinfarction2.8%1.9%1.9%0.37Ischemic target vessel revascularization3.2%2.8%3.0%0.92Death4.4%3.0%1.4%0.0065Major adverse cardiac events8.8%6.6%5.0%0.031Length of stay (d)7.1 ± 5.96.9 ± 6.36.7 ± 6.00.014 Open table in a new tab Clinical outcomes for 6 and 12 months are shown in Figure 1. Reinfarction and ischemic target vessel revascularization rates were no different at 6 and 12 months, regardless of BMI group. Major adverse cardiac events were significantly higher at 6 months in the normal BMI group, and at 12 months there was a trend toward significance. Mortality rates were lower at 6 and 12 months in the obese group (Figure 2). After separating patients by gender, death at 12 months was significantly lower in men in the obese group compared with men in the overweight and normal BMI groups (2.8% vs 4.9% vs 6.9% vs 11%, p = 0.04), even after subdividing the normal BMI group into normal and underweight categories. This difference was not apparent in women (6.7% vs 9.7% vs 11.0%, p = 0.39); however, the sample size of women was <33% of the total study population. On a separate analysis, we examined 12-month mortality in all patients with a final TIMI grade 50, 50 to 59, 60 to 69, >69 years of age). Elderly patients had a significantly higher incidence of death at 12 months, regardless of BMIs; however, mortality progressively decreased as BMI increased in elderly patients. Age >70 years, final TIMI grade 70 yrs<0.00014.092.63–6.35Final TIMI grade <3 flow<0.00013.942.29–6.78History of peripheral vascular disease0.00232.991.48–6.06Initial percent stenosis (increments of 10)0.0492.231.03–4.94Multivessel coronary artery disease0.0171.731.10–2.70Ejection fraction<0.00010.950.93–0.97Normal BMI0.271.290.82–2.02 Open table in a new tab The purpose of this study was to assess the association of BMI and outcomes after AMI in the contemporary mechanical reperfusion therapy era. Our initial hypothesis was that the obese patients would have worse short- and long-term outcomes after infarct-related PCI. In this study, 70% of patients were overweight or obese, whereas only 30% of patients had a normal BMI; these rates are close approximations to the current prevalence of obesity in the general population. We found obese and overweight patients to have a worse baseline history of cardiovascular risk factors, including diabetes, hypertension, and dyslipidemia. Despite a poor clinical profile, obese patients had fewer in-hospital groin bleeds, shorter length of hospital stay, and lower incidence of mortality in the hospital and at 12 months compared with patients with normal BMI. The BMI data are greatly confounded with other factors. Elderly patients were more frequently in the normal BMI group, and all previous data show elderly patients to have worse clinical outcomes after AMI regardless of treatment options. On average, obese patients were 6 years younger than those with normal BMI. Our multivariate analysis demonstrated final TIMI grade 70 years, history of peripheral vascular disease, and initial percent stenosis to be the strongest predictors of mortality at 12 months. Of these factors, younger age is most likely implicated in the confounded relation between higher BMI and AMI outcomes. This implies that AMI occurs at a younger age in the obese, and it is this younger age that counterbalances the risks that diabetes and hypertension pose in the immediate course of care. As part of being younger, obese patients may have received more aggressive or attentive care. Conversely, older patients, more likely to be in the normal BMI group, may not have fared as well with the treatment provided. Previous AMI studies have shown a higher incidence of morbidity and mortality in older patients regardless of treatment options.11Prasad A. Stone G.W. Zimetbaum P.J. McLaughlin M. Mehran R. Garcia E. Tcheng J.E. Cox D.A. Grines C.L. Gersh B.J. CADILLAC trialImpact of ST-segment resolution after primary angioplasty on outcomes after myocardial infarction in elderly patients: an analysis from the CADILLAC trial.Am Heart J. 2004; 147: 669-675Abstract Full Text Full Text PDF PubMed Scopus (72) Google Scholar, 12Tespili M. Guaglium G. Valsecchi O. Musumeci G. Vassileva A. Saino A. Scuri P.M. Gavazzi A. In-hospital clinical outcomes in elderly patients with acute myocardial infarction treated with primary angioplasty.Ital Heart J. 2003; 4: 193-198PubMed Google Scholar In addition, obese patients were less likely to be in Killip class >I, indicating they were comparatively more hemodynamically stable. Obesity is related to impaired fibrinolysis and increased platelet aggregation; hence, we observed fewer procedurally related bleeding events. Conversely, excess groin bleeds and blood transfusions in patients with normal BMI may be secondary to excess anticoagulation in the thinner cohort of patients. Anticoagulation regimens may not have taken into account the weight of the patient and the age-adjusted creatinine clearance for appropriate dose administration. The results of our study are comparable to those described by Hoit et al13Hoit B.D. Gilpin E.A. Maisel A.A. Henning H. Carlisle J. Ross J. Influence of obesity on morbidity and mortality after acute myocardial infarction.Am Heart J. 1987; 114: 1334-1341Abstract Full Text PDF PubMed Scopus (54) Google Scholar during the thrombolytic era in which the obese patients were younger, less likely to be women, and more often had a history of hypertension and diabetes compared with the normal BMI group. In-hospital mortality was similar in the obese and normal BMI groups and mortality at 12 months was significantly lower in the obese group. However, in the subset of patients >65 years of age, obese patients had a higher incidence of in-hospital mortality. Our study demonstrated that age >70 years was an independent predictor of death at 12 months; however, mortality progressively decreased as BMI increased in elderly patients. The results of this study are also similar to data described in patients with a spectrum of BMIs undergoing elective PCI in the angioplasty and stent eras.2Powell B.D. Lennon R.J. Lerman A. Bell M.R. Berger P.B. Higano S.T. Holmes Jr, D.R. Rihal C.S. Association of body mass index with outcome after percutaneous coronary intervention.Am J Cardiol. 2003; 91: 472-476Abstract Full Text Full Text PDF PubMed Scopus (91) Google Scholar, 4Gruberg L. Weissman N.J. Waksman R. Fuchs S. Deible R. Pinnow E.E. Ahmed L.M. Kent K.M. Pichard A.D. Suddath W.O. Satler L.F. Lindsay Jr, J. The impact of obesity on the short-term and long-term outcomes after percutaneous coronary intervention: the obesity paradox?.J Am Coll Cardiol. 2002; 39: 578-584Abstract Full Text Full Text PDF PubMed Scopus (537) Google Scholar These studies demonstrated that lean patients have significantly higher rates of in-hospital and long-term mortalities compared with obese patients. Obese patients were younger but comparatively had a worse baseline clinical profile, including diabetes, hypertension, and dyslipidemia. The protective effect of obesity was attributed to excessive anticoagulation or the possibility of significant underlying medical co-mordities in lean patients. However, despite appropriate weight-adjusted dosing of heparin and glycoprotein IIb/IIIa inhibitors, Gurm et al3Gurm H.S. Brennan D.M. Booth J. Tcheng J.E. Lincoff A.M. Topol E.J. Impact of body mass index on outcome after percutaneous coronary intervention (the obesity paradox).Am J Cardiol. 2002; 90: 42-45Abstract Full Text Full Text PDF PubMed Scopus (165) Google Scholar reported a lower risk of bleeding complications, urgent revascularization, AMI, and death in obese patients undergoing PCI. The mechanism for the disparity in BMI and outcomes was unclear, but angiographic differences were not believed to be contributing factors. The incidence of TIMI grade 3 flow after PCI was higher in the low BMI group and procedural success and postintervention creatinine kinase-MB were similar across BMI groups. There has also been a surge of data regarding the extreme ends of BMI and outcomes after elective PCI. Low-normal BMI and extreme obesity are correlated with adverse outcomes in the hospital due to excess vascular complications.14Ellis S.G. Elliott J. Harrigan M. Raymond R. Howell G. Low-normal or excessive body mass index: newly identified and powerful risk factors for death and other complications with percutaneous coronary intervention.Am J Cardiol. 1996; 78: 642-646Abstract Full Text Full Text PDF PubMed Scopus (128) Google Scholar Inappropriate anticoagulation dosing, respiratory complications from chronic obstructive lung disease, or nephrotoxicity in underweight patients are potential mechanisms. Adverse outcomes in extremely obese patients may be secondary to hypercoaguability from low plasminogen activator inhibitor 1 levels, delayed recognition of femoral access site hemorrhage, and difficult resuscitative measures during cardiopulmonary collapse. There are several limitations to this study. In many cases we relied on self-reported height and weight, thus introducing systematic error in calculating BMI. Prevalence rates of the overweight and obesity groups may have been slightly underestimated because weight is often underestimated and height is overestimated. We acknowledge that BMI is a crude indicator of body adiposity and, in cases of high lean tissue mass, BMI may overestimate adiposity. Our study has all the limitations of retrospective anlayses using prospectively collected data. Importantly, we could not control for age-related treatment biases that may have confounded the relations between BMI and outcomes. We did not have long-term outcomes evaluating the course of patients according to BMI. Because obese patients in general presented in their 50s, in the long run BMI may be a predictor of worsened outcomes over time, which is in contrast to the 1-year findings in our study. The authors thank Sue Tomaszycki for her technical assistance with the illustrations in this report.
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