Asian Cardiovasc Thorac Ann 2004;12:312-315
© 2004 Asia Publishing EXchange Ltd
Cardiac Surgery in an Iranian Teaching Hospital: Outcome and Risk Factors
Seyed-Ahmad Hassantash, MD,
Koorosh Mirpoor, MD,
Maryam Afrakhteh, MD
Department of Cardiovascular Surgery, Shahid Beheshti University of Medical Sciences, Tehran, Iran
For reprint information contact: Seyed-Ahmad Hassantash, MD Tel: 98 21 222 7330 Fax: 98 21 227 1119 Email: sahassan{at}pol.net Department of Cardiovascular Surgery, Modarres Medical Center, Shahid Beheshti University of Medical Sciences, Saadat-Abad, Tehran, Iran.
 |
ABSTRACT
|
|---|
Cardiac surgery in Iran has been associated with different facilities, equipment and patient populations in comparison to countries from which most of the academic papers used for identification of risk factors related to outcome and subsequent establishment of risk stratification models originate from. During a 15-month period all patients admitted for adult cardiac surgery using cardiopulmonary bypass (CBP) in a university affiliated teaching hospital were enrolled in a prospective study. Appropriate statistical tests were used to analyze data for mortality and morbidity. There were 730 adults (63% male, 37% female), with age ranged from 16 to 82 (mean, 51.4 ± 14.4). A mortality rate of 5.3% and morbidity of 14.8% (major + minor) were observed in the whole group. Factors correlated with mortality were: age ( p = 0.019), emergency surgery ( p < 0.0001), redo cardiac surgery ( p = 0.01), left ventricular (LV) aneurysm ( p < 0.001), presence of catastrophic states ( p < 0.001), low ejection fraction ( p = 0.04), history of hypertension ( p = 0.05), the individual surgeon ( p < 0.0001), and CPB duration ( p < 0.0001). Factors affecting morbidity included: female gender ( p = 0.04), age ( p = 0.03), emergency surgery ( p = 0.001), redo surgery ( p = 0.008), and catastrophic states ( p < 0.001). The mortality in our study group may be compared with reports presented in the literature. Factors such as age, emergency surgery, redo cardiac surgery, and catastrophic states are statistically related to both mortality and morbidity.
|
INTRODUCTION
|
|---|
Periodic evaluation of outcome is necessary in every facility for cardiac surgery considering the high cost of these surgeries.1,2 For this purpose, risk factors related to the patient population and the facilities are crucial. As long as risk factors are identified for the group of institutions in a certain area or continent, where cardiac surgeries are performed, appropriate risk stratification models can be established. While considerable information has been published from western countries on risk factors related to operative death of cardiac surgery, only a few studies have assessed such factors for both mortality and morbidity in the Asian Middle East population.1,20 This report from a teaching center describes the frequency and risk factors of these outcomes in a different set of facilities and different patient population.
|
PATIENTS AND METHODS
|
|---|
With both institutional and university review board approval, 750 consecutive patients undergoing cardiac surgery using CPB at Shahid Modarres hospital between February 2001 to March 2002 (15 months) were evaluated prospectively. This is a tertiary university hospital with a cardiac surgery residency program. No patient under 15 years of age was included in the study. Patients undergoing surgery without the association of CPB were excluded (patent ductus arteriosus ligation, pacemaker insertion, pericardial window creation). All potential risk factors were evaluated according to an information sheet which was completed during the treatment course. Other than the risk factors proposed by Parsonnet,3 the operating surgeon (6 surgeons) and some of the factors such as aortic cross clamping and CPB time were also evaluated.
The mortality and morbidity were considered as outcomes separately up to 30 days. Morbidities were divided into major and minor groups. Major complications included: postoperative low cardiac output syndrome, reoperation for bleeding, postoperative cerebral vascular accidents, acute pancreatitis, and sternal infection/dehiscence. Transient problems such as arrhythmias, small wound seroma/infections and jaundice were considered as minor morbidities. This information was obtained from the hospital database if the patient was still hospitalized and from clinic visits and inquiries over the telephone after discharge.
Statistical analysis was performed using SPSS software (version 11.0). Univariate analysis was used to test the association between mortality and the risk factors. Generally, Pearson’s chi-square test was used to evaluate relationship between risk factors and mortality. Fischer’s exact test was considered if the number of patients was low (less than 5) in one of the groups. A p-value of less than 0.05 was determined as statistically significant. Continuous variables, i.e. body mass index, ejection fraction, and age, were divided into two groups using an appropriate threshold and considering other reported papers for statistical purposes. To evaluate the effect of CPB time or aortic cross clamping time on mortality or morbidity, student’s t test was used. The same process was also performed for relating risk factors for major morbidities.
|
RESULTS
|
|---|
Seven hundred and thirty patients (37% female, 63% male) underwent cardiac surgery during the 15-month period with the mean age of 51 ± 14.4 years (16 to 82 years). A mortality rate of 5.3% was observed. Morbidity rate was 6.1% for major and 8.7% for minor complications (total = 14.8%). Table 1
summarizes the influence of each risk factor on mortality and morbidity in a univariate analysis. Significantly higher CPB time was observed in the mortality group compared to the surviving group (113 ± 46.9 minutes vs. 98.6 ± 37.1 minutes p < 0.0001). This was also true for morbidity (106.6 ± 40.9 vs. 97.1 ± 36.1 minutes, p = 0.03). Myocardial ischemic time, however, was not different in the mortality (74.3 ± 27 minutes) and surviving group (67.8 ± 36.4 minutes, p = 0.18). With regard to the relationship of the latter in the presence or absence of major morbidities, no statistical difference was found ( p = 0.22). A significant relationship was present between the individual operating surgeon and mortality ( p = 0.0001).
Among the female patients, 7.4% died in comparison to 4.1% in the male patients. The major and minor complications were 22% and 16%, respectively. Twenty four percent of the patients above the age of 65 years had some kind of morbidity verses 17% for the patients below this age. The mortality was 9.6% and 4.3%, respectively.
|
DISCUSSION
|
|---|
There have been many studies of risk factors in cardiac surgery.3–14 Most of them are from North America and in recent years from Europe. Their practices may not be necessarily applicable to Asia. This study was undertaken to establish an Asian, or more specifically, middle-eastern risk profile of cardiac surgery for the first time. It is accepted that this is a small series of patients from which to draw definite conclusions, however, this can be a starting point for further studies in the region or Asian continent. It is believed that the present study has produced valuable data, which is quite informative and can be used for future applications. The identified risk factors predisposing to cardiac surgery mortality and morbidity in the Middle East can be used to establish a risk stratification system for the prediction of hospital mortality and the assessment for quality of care.
Many risk factors have been associated with cardiac surgical mortality,4–14 they are preoperative patient characteristics, type and severity of the cardiac disease and the type and extent of the surgical procedure. Like most other studies, in addition to those risk factors present in Parsonnet’s3 original work, we also evaluated a few other objective and simple risk factors in this study. Some of the previous studies have stumbled in aspects which are either naturally complex, poorly defined, or both such as unstable angina, preoperative catastrophic states and associated diseases. To avoid ambiguity and loss of potential valuable information, we used simplified definitions and clear subclassifications for the variables. Regarding outcome evaluation there are at least four outcomes of interest to surgeons dealing with cardiac patients: mortality, morbidity (early or late, major or minor), resource utilization (length of ICU/hospital stay and cost), and patient satisfaction (the most complex to measure).15 Operative mortality is an easily defined, readily measured outcome, and its value to the patient is undeniable. The latter along with morbidity up to 30 days after surgery is measured in this study.
The information presented in this study is essential because of the profound differences between our setting in terms of facilities and patient population in comparison to the settings from where the usual reports come from. This database has, for the first time, provided a unique opportunity to assess the true cardiac surgery mortality rate and its risk factors in this framework. The differences are listed in Table 2. Most of them are related to shortage or non-usage of equipment and the non-engagement of other specialists in the cardiac surgerical team. A wide range of overall cardiac surgery mortality rates have been reported.11 Despite all the previously mentioned differences, the acceptable mortality rate of 5.3% and major morbidity rate of 6.1% in this study suggests that more adequate resources may be used in many other institutions. This can incur excessive costs on the patients or insurance providers and consequently on the community economy, in addition to extending unnecessary equipment use and providing the need for more sophisticated supplies.
Many of the preoperative risk factors identified as significant in our study such as age, ejection fraction, LV aneurysm, emergency surgery, presence of preoperative catastrophic state, redo surgery, for both mortality and morbidity have been identified elswere.16–18 Female gender was a contributing factor to mortality, although not reaching standard statistically significant levels ( p = 0.057), but was statistically significant as a risk factor for morbidity ( p = 0.04). In regard to operative factors, CPB time was significantly longer for both mortality ( p < 0.001) and morbidity ( p < 0.001). It must be taken into account that patients not coming off pump at surgery because of other reasons will have to be maintained on CPB for a longer time. Longer CPB time is, therefore, by itself dependent on poor patient condition and could not be considered as a risk factor for death. However, a longer CPB time may significantly contribute to postoperative morbidity ( p = 0.03). Interestingly, aortic cross clamping time is not a risk factor for death or morbidity ( p = 0.18 and 0.22, respectively). This encourages surgeons not to refrain from performing necessary and perfect procedure under cross clamping (accompanied by good myocardial protection) at the price of accomplishing lesser aortic cross clamping times.
An interesting finding of this study is a much higher female to male ratio in our patients. A female percentage of 37% is higher than any other report in the literature.2,19–20 Although there is a trend toward a higher proportion of women undergoing cardiac surgery in recent years,19 in our patient population a higher rate of valvular surgery compared to CABG may also be a contributing factor.5 This finding has encouraged us to conduct another study to verify the findings in a much larger patient population.
Presented at 11th Annual Meeting of the Asian Society for Cardiovascular Surgery (ASCVS), February 12–15, 2003, Kuala Lumpur, Malaysia.
|
REFERENCES
|
|---|
- Parsonnet V, Bernstein AD, Gera M. Clinical usefulness of risk-stratified outcome analysis in cardiac surgery in New Jersey. Ann Thorac Surg
1996;61:S8–11.
- Hannan EL, Kilburn H Jr, O’Donnell JF, Lukacik G, Shields EP. Adult open heart surgery in New York State. An analysis of risk factors and hospital mortality rates. JAMA
1990;264:2768–74.[Abstract/Free Full Text]
- Parsonnet V, Dean D, Bernstein AD. A method of uniform stratification of risk for evaluating the results of surgery in acquired heart disease. Circulation
1989;79:3–12.
- Roques F, Gabrielle F, Michel P, De Vincentiis C, David M, Baudet E. Quality of care in the adult heart surgery: proposal for a self-assessment approach based on a French multicenter study. Eur J Cardiothorac Surg
1995;9:433–9.[Abstract]
- Jamison WR, Edwards FH, Schwartz M, Bero JW, Clark RE, Grover FL. Risk stratification for cardiac valve replacement. National Cardiac Surgery Database. Database Committee of the Society of Thoracic Surgeons. Ann Thorac Surg
1999;67:943–51.[Abstract/Free Full Text]
- Higgins TL, Estafanous FG, Loop FD, Beck GJ, Blum JM, Paranandi L. Stratification of morbidity and mortality outcome by preoperative risk factors in coronary artery bypass patients. A clinical severity score. JAMA
1992;267:2344–8.[Abstract/Free Full Text]
- Tuman KJ, McCarthy RJ, March RJ, Najafi H, Ivankovich AD. Morbidity and duration of ICU stay after cardiac surgery. A model for preoperative risk assessment. Chest
1992;102:36–44.[Abstract/Free Full Text]
- Marshall G, Shroyer AL, Grover FL, Hammermeister KE. Bayesianlogit model for risk assessment in coronary artery bypass grafting. Ann Thorac Surg
1994;57:1492–500.[Abstract]
- Tremblay NA, Hardy JF, Perrault J, Carrier M. A simple classification of the risk in cardiac surgery: the first decade. Can J Anaesth
1993;40:103–11.[Medline]
- Tu JV, Jaglal SB, Naylor CD. Multicenter validation of a risk index for mortality, intensive care unit stay, and overall hospital length of stay after cardiac surgery. Circulation
1995;91:677–84.[Abstract/Free Full Text]
- Roques F, Nashaef SA, Michel P, Gauducheau E, DeVincentiis C, Baudet E, et al. Risk factors and outcome in European cardiac surgery: analysis of the EuroSCORE multinational database of 19030 patients. Euro J Cardiothoracic Surg
1999;15:816–22.
- Higgins TL, Estafanous FG, Loop FD, Beck GJ, Lee JC, Starr NJ, et al. ICU admission score for predicting morbidity and mortality risk after coronary artery bypass grafting. Ann Thorac Surg
1997;64:1050–8.[Abstract/Free Full Text]
- Turner JS, Morgan CJ, Thakrar B, Pepper JR. Difficulties in predicting outcome in cardiac surgery patients. Crit Care Med
1995;23:1843–50.[Medline]
- Tomasco B, Cappiello A, Fiorilli R, Leccese A, Lupino R, Romiti A, et al. Surgical revascularisation for acute coronary insufficiency: analysis of risk factors for hospital mortality. Ann Thorac Surg
1997;64:678–83.[Abstract/Free Full Text]
- Ferraris VA. Risk stratification and comorbidity. In: Edmunds LH Jr, editor. Cardiac surgery in the adult. 1st ed. New York: McGraw-Hill, 1997:165–90.
- Deiwick M, Tandler R, Mollhoff T, Kerber S, Rotker J, Roeder N, et al. Heart surgery in patients aged eighty years and above: determinants of morbidity and mortality. Thorac Cardiovasc Surg
1997;45:119–26.[Medline]
- Risum O, Abdelnoor M, Svennevig JL, Levorstad K, Gullestad L, Bjornerheim R, et al. Diabetes mellitus and morbidity and mortality risks after coronary artery bypass surgery. Scand J Thorac Cardiovasc Surg
1996;30:71–5.[Medline]
- Utley JR, Leyland SA, Fogarty CM, Smith WP, Knight EB, Feldman GJ, et al. Smoking is not a predictor of mortality and morbidity following coronary artery bypass grafting. J Card Surg
1996;11:377–84.[Medline]
- Edwards FH, Clark RE, Schwartz M. Coronary artery bypass grafting: the Society of Thoracic Surgeons National Database Experience. Ann Thorac Surg
1994;57:12–9.[Abstract]
- Grover FL, Hammermeister KE, Burchfiel C. Initial report of the Veterans Administration Preoperative Risk Assessment Study for Cardiac Surgery. Ann Thorac Surg
1990;50:12–28.[Abstract]
TOP
ABSTRACT
INTRODUCTION
