Anesthesiology 2003; 99:1287–94 © 2003 American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc. Tissue Factor and Platelet Glycoprotein Ib-␣ Alleles Are Associated with Age at First Coronary Bypass Operation Brian S. Donahue, M.D., Ph.D.,* Daniel W. Byrne, M.S.,† David Gailani, M.D.,‡ Alfred L. George Jr., M.D.§ Background: Age is a known risk factor for postoperative the impact of specific polymorphic variants in coagula- complications, but the genetic factors that account for variabil- tion system genes on age at first CABG. ity in age at presentation for surgery have not been character- Tissue factor (TF), which associates with factor VII to ized. Because thrombosis is a critical process in the develop- ment of coronary syndromes, the authors hypothesized that initiate activation of factor X, is present in activated 11,12 patients bearing the -1208 insertion allele of tissue factor (TF) endothelium and atherosclerotic plaque and may be ␣ ␣ and longer glycoprotein Ib- (GpIb ) variants may come to responsible for the events leading to coronary occlusion. Downloaded from http://pubs.asahq.org/anesthesiology/article-pdf/99/6/1287/338272/0000542-200312000-00009.pdf by guest on 27 September 2021 surgical attention sooner and undergo coronary artery bypass In addition, the glycoprotein Ib–IX–V complex, respon- grafting (CABG) at a younger age. The authors tested this hy- sible for platelet adhesion to the subendothelium via pothesis in a cardiac surgery population. 13 Methods: The impact of the number of TF -1208 insertion von Willebrand factor, also mediates key early events alleles and the number of GpIb␣ repeats on age at first CABG in thrombosis. Both TF and glycoprotein Ib have com- were tested in 424 elective coronary bypass patients. Multivar- mon genetic variants that may impact their respective iate regression included traditional risk factors of sex, hyper- activities. TF promoter polymorphisms comprise two tension, diabetes, hyperlipidemia, and smoking. The authors common haplotypes, characterized by the presence also tested the hypothesis that these alleles are correlated with age at first noncoronary cardiac surgery in a group of 143 (-1208 Ins) or absence (-1208 Del) of an 18-bp sequence patients undergoing noncoronary cardiac operations. at position -1208. The -1208 Ins allele has been associ- Results: Both the number of TF -1208 insertion alleles and ated with higher plasma TF concentrations and in- total number of GpIb␣ repeats were associated with younger creased risk for venous thromboembolism.14 The gene age at first CABG in a univariate analysis. In multivariate regres- for the glycoprotein Ib␣ (GpIb␣) subunit of the GpIb– sion in which traditional risk factors were included, the num- ber of TF -1208 insertion alleles and the total number of GpIb␣ IX–V complex contains a 39-bp variable number of tan- repeats were independent contributors toward age at first dem repeat (VNTR) polymorphism, resulting in one to CABG. Neither polymorphism had a significant impact on age at four repeats of a 13–amino acid sequence in the carbo- first noncoronary cardiac surgery. hydrate-binding region of the peptide. In several stud- ␣ Conclusions: Genetic variants in TF and GpIb are associated ies,15 the three- and four-repeat alleles have been asso- with younger age at first CABG, indicating that the younger and 16 older first-time CABG populations are different on the genetic ciated with increased risk for stroke, acute coronary 16,17 18 level. How these genetic differences may account for age-asso- syndromes, and sudden cardiac death. ciated differences in perioperative risk will be the subject of Because these proteins mediate initiation of thrombo- future investigations. sis, they represent reasonable candidates for association studies of cardiovascular risk. We were specifically inter- AGE is a known risk factor for complications of cardiac ested in whether these variants could impact coronary surgery. Adverse neurologic outcomes,1–4 renal dysfunc- disease progression and account for some of the variabil- tion,5 atrial fibrillation,6–8 gastrointestinal complica- ity in age at first CABG. tions,9 and hemostatic complications10 are all indepen- dently associated with advanced age. Although it is clear that patients present for their first coronary artery bypass Materials and Methods grafting (CABG) across a wide range of ages, the genetic factors that impact the age at first CABG have not been Patient Enrollment characterized. Because thrombus formation is a crucial This study was conducted after approval by the event in acute coronary syndromes, we sought to define Vanderbilt University Institutional Review Board (Nash- ville, Tennessee) and in accord with institutional guide- lines. We retrospectively examined the records of adult * Assistant Professor, Department of Anesthesiology, † Director of Biostatistics and Study Design, § Professor, Department of Medicine, ‡ Associate Professor, CABG patients in the Vanderbilt Cardiac Surgery Registry Departments of Medicine and Pathology. for whom the age at first CABG was known (n ϭ 424). Received from the Department of Anesthesiology, Vanderbilt University, Nash- This registry is an ongoing repository of cardiac surgery ville, Tennessee. Submitted for publication April 7, 2003. Accepted for publica- tion July 11, 2003. Supported by a Clinical Research Starter Grant from the patient data, with DNA storage and clinical data record Foundation for Anesthesia Education and Research, Mayo Clinic, Rochester, keeping, to facilitate studies of genetic variants and sur- Minnesota, and AstraZeneca Pharmaceuticals, Wilmington, Delaware; grant Nos. HL04476 and HL65962 from the National Institutes of Health/National Heart, gical outcomes. For patients undergoing second or sub- Lung, and Blood Institute, Bethesda, Maryland; and award No. RR00095 from the sequent CABG, the age at first CABG was determined by National Institutes of Health/General Clinical Research Center, Bethesda, Maryland. the date assigned to their first surgery, as listed in the Address reprint requests to Dr. Donahue: Department of Anesthesiology, 504 patient history. Patients undergoing emergency surgery Oxford House, Vanderbilt University, Nashville, Tennessee 37232. Address elec- tronic mail to: [email protected]. Individual article reprints may be and those with unstable hemodynamics were excluded. purchased through the Journal Web site, www.anesthesiology.org. For a control group, we included all adults from the Anesthesiology, V 99, No 6, Dec 2003 1287 1288 DONAHUE ET AL. registry who were undergoing first-time noncoronary C/D, and B/D heterozygous genotypes, determined by a cardiac surgery (mostly valve repair or replacement, sep- separate method, to serve as positive controls. Our re- tal defect repairs) and who did not have a history of sulting GpIb␣ VNTR genotyping method is as follows. coronary surgery (n ϭ 143). All patient care providers Amplification was performed in 25-␮l volumes consist- were blinded to patients’ genetic data. ing of 100 ng genomic DNA template; 1 U Taq polymer- ase; 10 pmol each primer (described by Kaiser et al.19); Definition of Parameters 50 ␮M each dNTP, with 50% of the dGTP present as Ethnicity consisted of patient-reported description, re- 7-deaza-dGTP; 10% betaine (Sigma); 7% dimethylsulfox- calling the last two generations. Diabetes and hyperten- ide; and buffer containing 10 mM Tris-HCl (pH 8.3 stock), sion were defined as present if included in the patient’s 1.5 mM MgCl2 and 150 mM KCl. Amplification cycles problem list on the preoperative evaluation. Current consisted of 10 cycles (94°C: 10 s; 55°C: 20 s; 68°C: Downloaded from http://pubs.asahq.org/anesthesiology/article-pdf/99/6/1287/338272/0000542-200312000-00009.pdf by guest on 27 September 2021 tobacco use was defined as the self-reported packs per 2 min), followed by 25 cycles (94°C: 10 s; 55°C: 20 s; day at the preoperative evaluation, and smoking history 68°C: 120 s ϩ 15 s/cycle), with ϩ15 denoting an exten- was defined in terms of packs per day and years smoked, sion of the elongation time by 15 s/cycle, and a final the product of which was pack-years. Because recent extension time of 7 min at 72°C. Because we predicted fasting lipid chemistries were not available for most that a gene-dose effect may be present regarding the patients, hyperlipidemia was defined as present if the number of VNTRs, we classified patients by the sum total patient was receiving lipid-lowering therapy at the time of GpIb␣ repeats carried on both chromosomes. For of preoperative evaluation. For brevity, we adopted the example, genotype C/D was classified as three total common nomenclature for the GpIb␣ alleles, referring repeats, genotypes C/C (the most common genotype) to them as A (four repeats), B (three repeats), C (two and B/D were each classified as four total repeats, geno- repeats), and D (one repeat). type B/C was classified as five total repeats, and so on. Genotype Analysis Statistical Analysis Blood was drawn for genotype analysis at anesthetic Allele frequencies were evaluated for Hardy-Weinberg induction, and DNA was isolated by standard protocols. equilibrium using a two-sided chi-square test. Because To evaluate the -1208 I/D polymorphism of the TF pro- the population was 92.6% white and 93% of the non- moter, we performed polymerase chain reaction (PCR) white patients were African-American (only three pa- amplification of a 99-bp segment (nucleotides -1145 to tients were neither white nor African-American), ethnic- -1243) of the TF gene. Amplification primers were 5'-GCA- ity was classified as white or nonwhite. The effects of the CAGTTTTATTCTGTTAAAACA-3' and 5'-CCTCTCTCCTT- number of -1208 Ins alleles and the total number of CTTTCCCACGTTT-3'. Amplification was performed in GpIb␣ repeats on age at first CABG were first evaluated ␮ 25- l volumes containing 100 ng DNA, 25 pmol each using one-way analysis of variance with linear contrast primer, 1 U Taq polymerase (Roche, Basel, Switzerland), for trend.