| Abstract|| |
Aims and Objectives: We evaluated the incidence and implications of coronary artery disease (CAD) in patients above 40 years presenting for valve surgery. Materials and Methods: Between January 2009 and December 2010, coronary angiography (CAG) was performed in all such patients ( n = 140). Results: Coronaries were normal in 119 (Group I), and diseased in 21 (Group II). In Group II, 11 patients were < 50 years, 3 were between 51 and 60 years and 7 were > 61 years. In 8 of these, only valve replacement was performed. Coronary artery bypass grafting (CABG) and aortic valve replacement was performed in 10, CABG and mitral valve replacement in 2 and CABG with mitral and aortic valve replacement in one. The number of vessels grafted in these 13 patients was 1.54 ± 0.66. Hypertension and diabetes were significant ( P < 0.05) in this group. The mortality was significant in Group II (11 vs. 6, P < 0.05). Six patients died in Group II, 5 had severe aortic stenosis and severe left ventricular hypertrophy; the sixth patient had severe mitral stenosis and was in CHF. The predominant cause of death was congestive heart failure (CHF). Conclusions: Fifteen percentage of these patients had CAD. CAG should be performed routinely in these patients while presenting for valve surgery. Combined CABG and valve replacement carries high mortality (28.5%), especially in patients with aortic stenosis. The study suggests that the cardio-protective measures should be applied more rigorously in this subset of patients.
Keywords: Cardiac surgery, Coronary artery bypass grafting, Coronary artery disease, Valve surgery
|How to cite this article:|
Tempe DK, Virmani S, Gupta R, Datt V, Joshi C, Dhingra A, Dutta R, Minhas HS. Incidence and implications of coronary artery disease in patients undergoing valvular heart surgery: The Indian scenario. Ann Card Anaesth 2013;16:86-91
|How to cite this URL:|
Tempe DK, Virmani S, Gupta R, Datt V, Joshi C, Dhingra A, Dutta R, Minhas HS. Incidence and implications of coronary artery disease in patients undergoing valvular heart surgery: The Indian scenario. Ann Card Anaesth [serial online] 2013 [cited 2019 Sep 17];16:86-91. Available from: http://www.annals.in/text.asp?2013/16/2/86/109732
This article is accompanied by an invited commentary by Dr. Harish Ramakrishna
| Introduction|| |
Elderly patients presenting for valve replacement may have concomitant asymptomatic coronary artery disease (CAD).  Lytle et al.,  observed that isolated surgical approach in the aortic valve had a negative impact on the operative mortality of patients with both CAD and valvular lesion. Karp et al.,  recommend that complete revascularization is superior to no revascularization in patients with valvular heart disease and CAD. A significant reduction in mortality is seen in such patients who undergo concomitant valve replacement and CABG.  Therefore, it is desirable to identify CAD in patients presenting for valve surgery. Coronary angiography (CAG) remains the gold standard for identifying such patients.  In India, the prevalence of rheumatic heart disease (RHD) is more than in the western world and some of these patients present after the third decade in advanced stage of the disease due to socio-economic reasons. However, the cut-off age for performing CAG in such patients is not clear. ,, In our institute with consensus of the team members, CAG is routinely performed in all patients at or above 40 years of age undergoing valve-replacement surgery. This prospective observational study was carried out with the aim of finding out the incidence and implications of CAD in such patients.
| Materials and Methods|| |
Between January 2009 and December 2010, 1562 adult patients underwent cardiac surgery in our institute. Out of these, 676 patients underwent valve replacement and 470 underwent CABG. CAG was performed in 140 patients who were ≥ 40 years of age and were scheduled for valve replacement. There were no exclusion criteria. Patients were divided into two groups: Group I (n = 119) wherein CAG revealed normal coronaries and Group II ( n = 21) wherein CAG revealed a lesion in the coronaries (presence of plaque, mild, moderate, or severe stenosis in one or more arteries). The decision to perform valve replacement alone or concomitant CABG and valve replacement was taken by the operating surgeon depending upon the severity of CAD.
Pre-operatively the data recorded were: demographic data, diagnosis, procedure planned, angiography report, ejection fraction (EF), and presence of any co-morbidity. All patients were pre-medicated with morphine 0.2 mg/kg body weight and promethazine 25 mg intramuscularly 1 h prior to surgery. In the operating room, a 23 G Y-cannula and radial artery cannula were inserted under local anesthesia. Anesthesia was induced with fentanyl 10-20 μg/kg, thiopentone sodium 50-100 mg and muscle relaxation was achieved with pancuronium bromide, vecuronium bromide, or rocuronium hydrochloride depending upon the lesion and baseline heart rate. Nitrous oxide in oxygen was administered (fractional inspired oxygen concentration [FiO 2 ] 0.5) before intubation. FiO 2 was reduced to 0.35 after intubation and increased to 1 before initiation of cardiopulmonary bypass (CPB). Patients were heparinized with 300 units/kg, 5 min before aortic cannulation and a further dose of 150 units/kg every hour during CPB with activated coagulation time maintained at >480 s. Standard CPB technique was followed using non-pulsatile flow @ 2-2.4 L/min/m 2 maintaining a temperature of 28-32°C with membrane oxygenator (affinity) and roller pump, with initial crystalloid prime volume of 1000 ml of lactated Ringer's solution and 250 ml of 18% mannitol. Cardiac arrest was induced and maintained using cold potassium containing blood cardioplegia solution delivered anterogradely using the cardioplegia delivery system and a 14 G needle inserted in the aortic root. The cardioplegia solution was repeated every 20 min for myocardial protection. After termination of CPB, heparinization was reversed with protamine in a ratio of 1.3 mg for every 100 units of initial dose of heparin. Intra-operatively, the perfusion and ischemia times and inotrope requirement were noted.
The primary end point of the study was the incidence of CAD in patients ≥ 40 years of age and the secondary end points were its implications in terms of the outcome (duration of elective ventilation, number of days for step-down of inotropes, length of stay in ICU, length of stay in hospital, the number of patients re-explored for excessive bleeding, and number of patients expired [death within 30 days of surgery]) as well as assessing possible predictive factors for the presence of CAD. Patients were considered to have a neurological complication, when a positive finding was detected on computed tomography scan in consultation with a neurologist.
Statistical analysis was performed using SPSS 17.0 software (SPSS Inc., Chicago, IL, USA). Continuous variables are presented as mean ± standard deviation (SD) and categorical variables are presented as absolute numbers and proportions. Means were compared using Student's t-tests. Pearson Chi-square and Fisher's exact test were used to analyze differences in categorical variables. A logistic regression model analysis was carried out in which CAD was considered the dependent variable and others as determinants. The variables included in this analysis were age, gender, body mass index (BMI), hypertension, diabetes, chronic obstructive pulmonary disease (COPD), chronic renal failure (CRF), and jaundice. Following convention, a " P" value of < 0.05 was considered statistically significant.
| Results|| |
[Table 1] shows the pre-operative data in the two groups. There were more males in Group II, and the age, BMI and pre-operative hemoglobin levels were comparable. The Euroscore was significantly more in Group II. Angiography revealed the presence of CAD in 11 patients < 50 years of age, three patients between 51 and 60 years of age, and seven patients > 61 years of age [Table 2]. [Table 3] shows various co-morbidities observed in the two groups. Diabetes and hypertension were significantly more commonly associated in patients who had concomitant CAD.
The most common surgical procedure in Group I [Table 4] was mitral valve replacement (MVR, n = 69) followed by double valve (mitral and aortic) replacement (DVR, n = 21) and aortic valve replacement (AVR, n = 21). In Group II, CABG and AVR was performed in 10 patients, CABG and MVR in two patients, and CABG and DVR in one patient. Concomitant CABG was performed in two patients who had triple-vessel disease, eight patients who had double-vessel disease, and three patients who had a significant lesion in the left anterior descending artery. In the remaining eight patients, concomitant CABG was not performed and only valve replacement was performed, as the surgeon did not consider the coronary lesion significant enough to warrant CABG [Table 5].
[Table 6] shows the intra-operative details. The duration of CPB and ischemia were longer in Group II, but not statistically significant. The other parameters such as duration of elective ventilation, lowest Hb on CPB and Hb at the time of transfer to ICU were similar in the two groups. Transfusion of fluids, blood, and blood products was more in Group II, but the difference between the two groups was not statistically different. The mean number of vessels grafted in the 13 patients who underwent combined CABG and valve replacement was 1.5 ± 0.66. Adrenaline, dopamine, and dobutamine were the inotropes used either alone or in combination, during separation from CPB. [Table 7] shows the outcome in terms of the number of days for step-down of inotropes, length of stay in ICU, length of stay in hospital, the number of patients re-explored for excessive bleeding, and number of patients who died. The mortality was significantly higher in Group II [11 patients (9.2%) in Group I vs. 6 patients (28.6%) in Group II, P < 0.05).
[Table 8] shows the details of the six patients who died in Group II. Five had severe AS and the predominant cause of death was congestive heart failure. Although patient number 1 underwent only AVR (LCX was 50% stenosed) and eventually died of septicemia, the patient also had congestive heart failure (CHF) requiring prolonged inotropic and ventilatory support in the post-operative period. The patient number 5 had severe MS with a valve area of 0.72 cm 2 and was in CHF before surgery.
| Discussion|| |
In 1980, Morrison et al.,  performed elective CAG in adult patients and concluded that asymptomatic significant coronary lesion exists in 33% of patients > 45 years of age scheduled for valve replacement. The peri-operative mortality (within 4 weeks of valve replacement) with combined CABG was higher (20%) as compared with valve replacement alone (5.9%). They concluded that as there are no adequate clinical markers of CAD in patients with valvular heart disease, routine CAG should be a part of the pre-operative investigation, but there was no data to recommend the lower age limit. Since then, the reported incidence of CAD in patients presenting for valve replacement has varied from 3% to 20% in different reports ,, depending upon the age at which routine angiography was performed (≥ 35 to ≥ 40 years), risk factors, and eating habits which differ in the different populations that have been studied. The results of the combined procedures (CABG and valve replacement) have also shown considerable improvement with more recent papers reporting an early mortality of 2-11% for AVR and CABG ,,, and 8-11% for MVR and CABG. , These findings suggest that combined valve replacement and CABG should be performed in case CAD is detected in a patient undergoing valve replacement. In the present study, the incidence of CAD is 15% in patients ≥ 40 years of age. This is similar to the one reported by Bozbas et al.,  (18.8%) who performed angiography in all patients above 40 years of age and in those < 40 years of age, if there was a clinical suspicion of CAD. However, they reported that only seven patients out of 41 were < 50 years of age with the youngest being a 40-year-old male with history of angina pectoris. They concluded that CAG can be omitted in patients below the age of 40 if there was no angina or coronary risk factors. They also reported that patients with CAD had significantly increased prevalence of diabetes, hypertension, history of smoking, and family history of CAD. Sampaio et al.,  identified a low prevalence of obstructive CAD (3.42%), with aortic valve pathology being the most frequent lesion associated with CAD and most of the patients being over 50 years of age. In fact, they challenged CAG as a pre-operative examination, especially in younger patients with valve pathology as none of their patients below 50 years of age, with no risk factor for CAD, had CAD. Kruczan et al.,  also recommend that CAG should not be performed indiscriminately in all patients, but for those who present a clear clinical evidence and predictive factor of the disease. According to the 2008 ACC AHA guidelines, CAG is indicated before valve surgery in men aged 35 years or older, pre-menopausal women aged 35 years or older who have coronary risk factors, and post-menopausal women (Level of evidence: C).  In the present study, CAD was detected in 8 patients (5.7%) < 45 years of age without any co-morbidity. These results suggest that CAG can be considered in all patients above 40 years of age presenting for valve replacement otherwise these 5.7% patients would have been missed.
In the present study, CAD was complicating the valvular heart disease (both rheumatic and non-rheumatic) but was not a cause of valvular dysfunction. When we consider the type of valve pathology and associated CAD, the prevalence of CAD among patients with rheumatic valvular heart disease is low and has been reported to vary from 4 to 14%. ,,, On the other hand, in sclero-degenerative AS the incidence of CAD is reported to be as high as 37% in patients aged between 40 and 59 years and 64% in those between 60 and 82 years. 
The operative mortality of patients undergoing MVR and CABG has been higher than those undergoing AVR and CABG. In early days, the mortality has been reported to be as high as 19%  in patients undergoing MVR (rheumatic and degenerative) and 30%  in patients with ischemic MR. This has been explained on the basis of poor functional class, severe MR-related volume overloaded ventricle and its failure to resume adequate function after a prolonged combined procedure, unstable ischemia, extensive CAD, compromised left ventricular function, and an elevated pulmonary vascular resistance. However, over the years, the mortality has considerably improved to 8% to 11%. , For combined AVR and CABG, the mortality has been relatively less, with earlier papers reporting a mortality of 10%  and the more recent ones reporting 2-11%. ,,, This is in stark contrast to our results where an overall mortality of 28.5% was observed in the combined procedure (in five patients of AVR and CABG and one patient of MVR and CABG). It is also noteworthy that in the present study, five out of six patients who died had severe AS. In combined AVR and CABG, LV dysfunction has been reported to be a risk factor. 
In India, patients present late with advanced disease with severe LVH (in those who died, the septal wall thickness was in the range of 1.5-1.75 cm and the valve area was in the range of 0.8-1.2 cm2), therefore, the mortality in them can be attributed to subendocardial ischemia despite special attention being given to myocardial protection by way of cooling the patient to 28°C and repeated dose of antegrade cold blood cardioplegia administered every 20 min. In an earlier report, Czer et al.,  have shown that co-existent CAD had no detrimental effect on mortality, if concomitant AVR and CABG is performed (early mortality 6.8%), but the mortality increased significantly, if CABG was not performed. They attributed the late cardiac mortality to the occurrence of late sudden death (42%) especially in the unbypassed CAD group. More recently, Gunay et al.,  report an overall operative mortality of concomitant AVR-CABG as 10%, with AS having a higher mortality (11.2%) than AR (5%), although their difference was not statistically significant. The increase in mortality in the AS group could be related to a smaller aortic valve size, higher mean age, female patients, and that the AS group may have increased subendocardial ischemia rates related to CAD with LV hypertrophy. Backeria et al.,  have also reported that severe LVH with narrow aortic fibrous annulus and small diastolic LV volume are associated with increased operative mortality in patients undergoing concomitant CABG and AVR. During CPB and cardioplegic arrest, the hypertrophied heart is more susceptible to inflammatory response and ischemia-reperfusion injury and may require additional protective measures.  Therefore, among patients who undergo concomitant CABG and valve surgery, especially those who have severe AS (hypertrophied LV), the prognosis in terms of mortality can be alarming and that the myocardial protection during the procedure should be taken care of (by way of inclusion of warm cardioplegia, retrograde cardioplegia, continuous perfusion, and the inclusion of various additives that aim at reducing Ca 2 + overload, provide energy substrates, and remove harmful reactive oxygen species). ,
| Conclusion|| |
Significant proportion of patients above 40 years of age can have CAD (15%). This being of therapeutic as well as of prognostic importance, CAG should be done in patients > 40 years of age even in the absence of any risk factor. Combined CABG and aortic valve replacement in AS carries a risk of high mortality which may be related to hypertrophied LV and susceptibility to suffer from subendocardial ischemia.
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Deepak K Tempe
Department of Anaesthesiology and Intensive care, G. B. Pant Hospital, New Delhi - 110 002
Source of Support: Institutional, Conflict of Interest: None
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8]