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Ann Thorac Surg 2004;78:2028-2032
© 2004 The Society of Thoracic Surgeons

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Original article: cardiovascular

Factors Associated With Presence of Ascending Aortic Atherosclerosis in CABG Patients

^a Department of Cardiac Surgery, Innsbruck University Hospital, Innsbruck, Austria

Accepted for publication April 20, 2004.

^* Address reprint requests to Dr Bonatti, Department of Cardiac Operation, Innsbruck University Hospital, Anichstrasse 35, Innsbruck 6020, Austria.
johannes.o.bonatti{at}uibk.ac.at

	Abstract

Top Abstract Introduction Patients and Methods Results Comment Conclusion Acknowledgments References

 
BACKGROUND: The indication for epiaortic scanning during coronary artery operation is still a matter of debate. Whether this test should be carried out selectively or on a routine basis is unclear. The aim of this study was to determine factors that predict the presence of atherosclerotic ascending aortic wall thickening in patients undergoing coronary artery bypass grafting (CABG).

METHODS: A total of 500 CABG patients underwent epiaortic scanning using a high-frequency linear ultrasonic probe. Maximum ascending aortic wall thickness was measured and correlated with patient-related variables.

RESULTS: Maximum ascending aortic wall thickness significantly correlated with age (p < 0.001), preoperative creatinine level (p = 0.004), European system for cardiac operative risk evaluation (EuroSCORE, p < 0.001), and maximum descending aortic wall thickness (p < 0.001). Body mass index and left ventricular ejection fraction showed no correlation with maximum ascending aortic wall thickness. Of the categorical variables, hypertension (p = 0.02), unstable angina (p = 0.04), chronic obstructive pulmonary disease (p = 0.02), cerebrovascular disease (p < 0.001), and peripheral vascular disease (p < 0.001) were associated with increased ascending aortic wall thickness whereas sex, diabetes, acute cases, and previous cardiac operation were not. Multivariate analysis revealed maximum descending aortic wall thickness (p < 0.001), cerebrovascular disease (p = 0.03), and peripheral vascular disease (p = 0.04) as independent variables significantly associated with maximum ascending aortic wall thickness.

CONCLUSIONS: If epiaortic scanning is not carried out routinely for detection of ascending aortic arteriosclerosis it should at least be performed in patients with old age, hypertension, unstable angina, chronic obstructive pulmonary disease, cerebrovascular disease, peripheral vascular disease, elevated creatinine levels, higher EuroSCOREs, and increased wall thickness of the descending aorta.

	Introduction

Top Abstract Introduction Patients and Methods Results Comment Conclusion Acknowledgments References

 
Cerebrovascular accidents are an important concern during cardiac operation [1]. Atheroemboli from the ascending aorta are an important cause of stroke in patients undergoing cardiac operation [2]. The embolization rate is correlated with the severity of ascending aortic arteriosclerosis [3, 4], and severe arteriosclerosis of the ascending aorta increases the risk of postoperative neuropsychologic dysfunction and stroke after coronary artery bypass grafting (CABG) [5, 6]. Ascending aortic arteriosclerosis can be determined easily and accurately by epiaortic scanning [7, 8]. However use of epiaortic scanning is still a matter of debate. Some surgeons advocate the use of this examination in all cases whereas others prefer a selective application. Although some authors have found factors associated with ascending aortic arteriosclerosis, the population at risk for this disease still needs to be more closely determined. Therefore the aim of our study was to determine risk factors associated with ascending aortic wall thickening in patients undergoing CABG.

	Patients and Methods

Top Abstract Introduction Patients and Methods Results Comment Conclusion Acknowledgments References

 
Between 1998 and 2003 500 CABG patients underwent epiaortic scanning using a 7.5-MHz linear ultrasound probe (Site Rite II, Dymax Inc, Pittsburgh, PA) after sternotomy and opening of the pericardium. A film of ultrasound gel was applied on the tip of the probe and a sterile plastic bag was wrapped around the tip. In cases of inadequate visualization of the anterior aortic wall, the pericardial sac was filled with saline solution to create a better acoustic transmission. The ascending aortic wall thickness was measured in longitudinal and transversal axes and the maximum values were used for calculations in this study. Descending aortic wall thickness was determined by transesophageal echocardiography (TEE; Sonos 5500, Hewlett-Packard Company, Palo Alto, CA), which is performed in all our patients undergoing cardiac operation. All TEEs were performed independently from epiaortic ultrasound by the attending anesthesiologist. Patient characteristics are listed in Table 1.

Ascending aortic arteriosclerosis was graded as normal/mild (aortic wall less than 3 mm), moderate (aortic wall 3 to 5 mm), and severe (aortic wall thickness more than 5 mm or the presence of marked calcification, protruding or mobile intraluminal atheromatous portions, and ulcerated plaques) according to the classification reported by Wareing and coworkers [10].

Statistical Analysis
Statistical analysis was carried out using the SPSS 10.0 software (SPSS Inc, Chicago, IL). Continuous variables are given as mean ± standard deviation. Categorical variables are given as percentage. Spearman correlation coefficients () were calculated for continuous variables. The Mann-Whitney U test was applied for comparisons of maximum ascending aortic wall thickness between categorical factors.

Multivariate analysis for the independent effect on maximum ascending aortic wall thickness of the factors that have been found to be associated with maximum ascending aortic wall thickness in the univariate analysis was performed using a general linear model. Significance was determined at p < 0.05.

	Results

Top Abstract Introduction Patients and Methods Results Comment Conclusion Acknowledgments References

 
The ascending aortic wall could be adequately visualized and measured in all patients. The results of prediction of ascending aortic atherosclerosis by inspection and palpation in different stages of aortic atherosclerosis are summarized in Table 2. We found a sensitivity of 98% for inspection and of 92% for palpation. The specificity for detecting moderate atherosclerosis was 4% for inspection and 24% for palpation. The specificity for detecting severe arteriosclerosis was 27% for inspection and 80% for palpation.

View larger version (21K): [in this window] [in a new window]   Fig 1. Correlation between age (years) and maximum ascending aortic wall thickness (MAAWT) in 500 patients who underwent coronary artery bypass grafting. The regression line was significant (p < 0.001) and followed the function: y = 0.041 x age + 0.71, where y = MAAWT (in millimeters).

View larger version (21K): [in this window] [in a new window]   Fig 2. Correlation between preoperative serum creatinine levels (mg/dL) and maximum ascending aortic wall thickness (MAAWT) in 490 patients who underwent coronary artery bypass grafting (data of 10 patients with creatinine levels > 2.5 mg/dL are not shown). The regression line was significant (p < 0.001) and followed the function: y = 1.14 x serum creatinine level + 2.10, where y = MAAWT (in millimeters).

View larger version (17K): [in this window] [in a new window]   Fig 3. Correlation between European system for cardiac operative risk evaluation (EuroSCORE) and maximum ascending aortic wall thickness (MAAWT) in 500 patients who underwent coronary artery bypass grafting. The regression line was significant (p < 0.001) and followed the function: y = 0.12 x EuroSCORE + 2.83, where y = MAAWT (in millimeters).

View larger version (17K): [in this window] [in a new window]   Fig 4. Correlation between maximum descending aortic wall thickness (MDAWT in millimeters) and maximum ascending aortic wall thickness (MAAWT) in 500 patients who underwent coronary artery bypass grafting. The regression line was significant (p < 0.001) and followed the function: y = 0.35 x MDAWT + 2.06, where y = MAAWT (in millimeters).

	Comment

Top Abstract Introduction Patients and Methods Results Comment Conclusion Acknowledgments References

 
In our study we demonstrated that palpation and inspection of the ascending aorta are too insensitive for detecting aortic atherosclerosis. In cases of moderate atherosclerosis less than one third would have been suspected by palpation and less than 5% would have been suspected by inspection. This finding is in agreement with those of Davila-Roman and coworkers [7], who found epiaortic ultrasound to be superior to both TEE and palpation for diagnosis of atherosclerosis of the ascending aorta. If epiaortic scanning cannot be carried out in all patients the procedure should be considered in patients at risk for ascending aortic atherosclerosis.

We identified age to be correlated with maximum ascending aortic wall thickness. Age is also known risk factor for aortic atherosclerosis. The average age of the population with aortic atheromas is approximately 70 years [11].

We also found that patients with elevated serum creatinine levels were at risk for ascending aortic atherosclerosis. This finding is in agreement with those from Goto and coworkers [5]. Davila-Roman and coworkers [12] demonstrated that arteriosclerosis of the ascending aorta is a predictor for renal dysfunction after cardiac operation in patients with preoperatively normal renal function. Our findings, combined with those of Davila-Roman and coworkers [12], suggest a relation between preoperative renal retention (as evidenced by elevated serum creatinine levels) and ascending aortic atherosclerosis. This relation may be related to an atherosclerotic process that also involves the renal arteries or even to atheroembolic damage of the kidneys.

Patients with higher EuroSCOREs were also found to be at risk for ascending aortic atherosclerosis. Of 17 factors contributing to the EuroSCORE only 2 factors (ie, age and extracardiac arteriopathy) represent known risk factors for aortic arteriosclerosis [11]. Nevertheless the EuroSCORE was associated with ascending aortic atherosclerosis.

Maximum descending aortic wall thickness correlated with maximum ascending aortic wall thickness in our series. Identification of this risk factor is possible because TEE is commonly used in cardiac operation. Van der Linden and coworkers [13] demonstrated that patients with atherosclerotic disease in the ascending aorta had a higher incidence of atherosclerotic disease in the aortic arch and in the descending aorta.

Interestingly, body mass index was not correlated with maximum ascending aortic wall thickness in our series. In contrast to our finding Davila-Roman and coworkers [14] found an association of ascending aortic arteriosclerosis with a lower body mass index. Preoperative left ventricular ejection fraction was also found not to be correlated with maximum ascending aortic wall thickness in our patients.

Male sex and diabetes mellitus were also not correlated with maximum ascending aortic wall thickness. This finding is in accordance with those by Davila-Roman and coworkers [14]. Yet in a subgroup of elderly patients (60 years and older) Goto and coworkers [5] found a higher rate of male patients in the group of moderate and severe ascending aortic arteriosclerosis than in the control group.

Cerebrovascular disease was associated with ascending aortic atherosclerosis in our series. This finding is in agreement with other authors who demonstrated that carotid artery disease is associated with aortic arteriosclerosis [11, 13–15].

Peripheral vascular disease was also associated with ascending aortic atherosclerosis in our series. Van der Linden and coworkers [13] found that patients with ascending aortic arteriosclerosis had a higher incidence of intermittent claudication.

Hypertension was also associated with ascending aortic atherosclerosis. On the one hand, hypertension had been found previously to be a risk factor for aortic atheromas [11]. However, Davila-Roman and coworkers found no association between hypertension and ascending aortic arteriosclerosis [14].

Another interesting association was noted between ascending aortic atherosclerosis and COPD. An association exists between COPD and abdominal aortic aneurysms [16, 17]. However, we can only speculate on the mechanism of COPD as a risk factor for ascending aortic atherosclerosis; its effect was undetectable on multivariate analysis.

From a surgical point of view we found that redo cardiac operation and acute cases were not significantly associated with atherosclerosis of the ascending aorta, whereas unstable angina was associated with the disease.

	Conclusion

Top Abstract Introduction Patients and Methods Results Comment Conclusion Acknowledgments References

 
We conclude that epiaortic scanning is an adequate tool for determining the ascending aortic wall thickness in patients undergoing coronary operation. If epiaortic scanning is not used regularly it should at least be performed in patients with old age, hypertension, unstable angina, COPD, cerebrovascular disease, peripheral vascular disease, elevated serum creatinine levels, higher EuroSCORE, and increased wall thickness of the descending aorta.

	Acknowledgments

Top Abstract Introduction Patients and Methods Results Comment Conclusion Acknowledgments References

 
We thank Dr Alexandar Tzankov for his help with statistical analysis.

	References

Top Abstract Introduction Patients and Methods Results Comment Conclusion Acknowledgments References

 

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