Ann Thorac Surg 2003;75:501-504
© 2003 The Society of Thoracic Surgeons
Original article: cardiovascular
Internal thoracic artery grafts for the entire heart at a mean of 12 years
Lester R. Sauvage, MDa,b,d*,
Joshua G. Rosenfelda,b,
Paul V. Roby, MDa,b,
David M. Gartman, MDc,
William P. Hammond, MDa,b,e,
Lloyd D. Fisher, PhDf
a The Hope Heart Institute, University of Washington, Seattle, Washington, USA
b Providence Seattle Medical Center, University of Washington, Seattle, Washington, USA
c Swedish Medical Center, University of Washington, Seattle, Washington, USA
d Department of Surgery, University of Washington, Seattle, Washington, USA
e Department of Medicine, University of Washington, Seattle, Washington, USA
f Department of Biostatistics, University of Washington, Seattle, Washington, USA
Accepted for publication August 21, 2002.
* Address reprint requests to Dr Sauvage, The Hope Heart Institute, 528 18th Ave, Seattle WA 98122, USA.
e-mail: lsauvage{at}hopeheart.org
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Abstract
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BACKGROUND: There is consensus today that the long-term results of bypassing the left anterior descending artery with an internal thoracic artery (ITA) graft are superior to those of a saphenous vein graft. Our hypothesis for this study was that three-vessel revascularization with only ITA grafts would also give excellent results.
METHODS: Using our previously described techniques to enhance the length of ITA grafts by skeletonization and high mediastinal mobilization, we were able to perform tension-free, three-vessel revascularization using only ITA grafts in 125 (83%) of a consecutive series of 150 patients with three-vessel occlusive coronary disease. We followed 100% of these 125 exclusive ITA graft patients (average of 3.9 anastomoses per patient) to their time of death (59; 47.2%) or current living status (66; 52.8%).
RESULTS: Combined intraoperative graft flows averaged 225 mL/min. Of the 125 patients in this study (average age, 63.5 years), 121 (96.8%) lived beyond 40 days. Of these 121 patients, 55 (45%) died at a mean of 7 years postoperatively and 66 (55%) are still living at a mean of 12.1 years. Of these 121 patients, 112 (93%) had angina at baseline. Of these 112, 92 (85%) were angina free at a mean of 9.1 years postoperatively. Freedom from infarction was 100% at 5 years and 97% at 10 years. Freedom from reintervention was 90% at a mean of 9.8 years.
CONCLUSIONS: Use of ITA grafts for three-vessel coronary revascularization provides excellent results and is both practical and appropriate for many patients.
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Introduction
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Tector and associates [1] have shown that three-vessel coronary revascularization (left anterior descending [LAD], circumflex [CX], and right coronary artery [RCA]) with only internal thoracic artery [ITA] grafts (used in a T or tandem manner with sequential anastomoses as needed) can be done safely with excellent results at a mean follow-up of 4.2 years. In this paper, we present the operative risks and longer-term results of a similar but smaller series followed for a mean of 12.1 years.
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Material and methods
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Case selection
Of 150 consecutive patients undergoing three-vessel (LAD, CX, and RCA) bypass by one surgeon (LRS) between March 20, 1985 and February 15, 1988, 125 (83%) received only ITA grafts. This exclusive-ITA procedure was performed for all nonemergency (elective or urgent) patients whose ITAs were satisfactory. Baseline clinical characteristics of our ITA patients are summarized in Table 1.
The exclusive-ITA procedure was not employed if the patient required emergency revascularization or the ITAs were not satisfactory for this procedure. Of these 150 three-vessel patients, 25 (17%) required the use of at least one vein graft for these reasons.
The coronaries proximal to the sites of the three-vessel exclusive-ITA graft anastomoses were either occluded or severely stenotic. Similarly, of the 14 exclusive-ITA patients who had received previous saphenous coronary artery bypass graft (CABG) procedures, the saphenous grafts were either occluded or severely stenotic.
Surgical technique
Extensively mobilized, skeletonized bilateral ITA grafts were used, with as many sequential coronary anastomoses as necessary (Fig 1)
[2, 3]. The total number of graft-to-coronary anastomoses averaged 3.9 (three to six per patient). Graft blood flow was measured intraoperatively with an electromagnetic flow meter. Procedures were selected from the three strategies (or closely related variations) shown in Figure 1.
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Fig 1. Strategies for complete three-vessel coronary artery bypass grafting using only internal thoracic artery (ITA) grafts, depending on graft length and coronary target sites. Shown are operative sketches and composite films from 3 patients, one for each strategy, during the follow-up period. Angios in A were performed after an episode of congestive failure, in B after a near-fainting episode, and in C for evaluation of a positive treadmill response (no angina). Arrows identify anastomoses. Number of patients receiving each strategy, average aggregate flow rates, and postoperative intervals are given. (A) Angiograms performed 6 years after Strategy I procedure in male patient, age 42 at time of surgery. In most Strategy I cases, the LITA was anastomosed first to the circumflex and then to the LAD. (B) Angiograms performed 12 years after Strategy II procedure in male patient, age 63 at the time of surgery. (C) Angiograms performed at 11 years after Strategy III procedure in male patient, age 67 at time of surgery. RITA was used as a free graft in constructing LITA-RITA bifurcation graft. (CABG = coronary artery bypass graft; LAD = left anterior descending; LITA = left ITA; RITA = right ITA.)
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The choice of strategy depended on the length of the ITAs and the distance to the target vessels. Strategy III was employed for patients with short ITAs. This strategy, which preserves the distal ITA and its superior epigastric and musculophrenic divisions and requires minimal extension of the skin incision or dissection into the epigastrium, was favored for obese patients, especially if diabetic, to avoid necrosis of epigastric fat.
Follow-up
All patients were followed with no loss to follow-up. Follow-up duration was calculated from the date of operation to the date of death or actual last direct contact either by phone or personal interview. After hospital disharge, all patients were seen within 3 weeks. Through 1991, 54% were followed by yearly visits, 18% by questionnaires, and 27% by telephone conversation. All surviving patients were again contacted by phone or in person in each of the years 1994, 1996, and 1998. Whenever follow-up angiograms were performed (usually for nonspecific chest discomfort), results were noted. Data on cause of death came from autopsy findings, the families, the patients’ physicians, or medical records.
Anginal status was classified according to the New York Heart Association Classification System [4]. Postoperative myocardial infarction (MI) was diagnosed on the basis of enzyme or electrocardiogram (ECG) evidence. Reintervention was defined as having postoperative coronary artery bypass grafting (CABG) or a percutaneous transluminal coronary angioplasty (PTCA) procedure.
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Results
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Graft flow rates
Total intraoperative graft flows averaged 225 mL/min (191 for strategy I, 248 for strategy II, and 201 for strategy III) (Fig 1).
Perioperative mortality and morbidity
Thse results are shown in Table 2.
There were no intraoperative deaths. Four patients died in the hospital in 40 or fewer days (3.2%). Of these early deaths, one was due to ventricular fibrillation at 1 day (grafts patent at autopsy) and three were due to multiple organ system failure at 13, 30, and 40 days (autopsies not performed).
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Table 2. Perioperative Mortality and Morbidity in Exclusive-ITA CABG Series (N = 125) for Three-Vessel Revascularization
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Mediastinitis did not occur. Superficial wound infection occurred in 6 patients (4.8%). Deeper wound infection requiring limited outer table sternal curettage occurred in three patients (2.4%). Reoperation for bleeding was necessary in 2 patients (1.6%). Pleural effusion requiring aspiration was necessary in 14 patients (11.2%). Temporary unilateral phrenic nerve impairment (elevated hemidiaphragm) occurred in 5 patients (4%). Mechanical ventilation beyond 1 day was necessary in 15 (12%) patients.
Late mortality
Of the 121 patients living beyond 40 days, follow-up was 100%, with 55 patients dying at an average of 7 years postoperatively (range, 3 months to 12.3 years), and 66 patients known living at an average of 12.1 years postoperatively (range, 10.7 to 13.6 years). The average follow-up of these 121 patients was 9.8 years. Of the 55 late deaths, 18 (33%) were classified as cardiac in origin (10 due to progressive congestive failure, 7 to unexplained sudden death, and 1 to MI). The remaining deaths were due to malignancy (14; 25%), stroke (7; 13%), pulmonary disease (4; 7%), renal disease (3; 5%), trauma (2; 4%), and other noncardiac causes (7; 13%).
Among the 55 deceased patients, nine autopsies were performed; all anastomoses were patent in eight at a mean of 4.3 years after surgery. The ninth autopsy, performed 10 years after surgery, showed that four of five anastmoses were patent.
All-cause mortality
The proportion of patients surviving after complete three-vessel CABG using only ITA grafts is shown in Figure 2.
The survival at 10 years is 61.6% (95% CI, 52.5% to 70.2%).
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Fig 2. This Kaplan-Meier survival curve shows the proportion of patients surviving after complete three-vessel coronary bypass using only internal thoracic artery grafts. Steps in the curve represent individual fatalities with censoring at that point. Tick marks indicate survival periods of individual patients living at last follow-up, with average follow-up of 12.1 years (range, 10.7 to 13.6 years).
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Postoperative angiography
Thirty-two patients underwent angiography during follow-up, usually for nonspecific chest discomfort. Of their 73 left internal thoracic artery (LITA) and 46 right internal thoracic artery (RITA) coronary anastomoses, 62 (85%) LITA and 40 (87%) RITA anastomoses were patent at a mean of 7.4 years (range, 11 days to 12.9 years) after operation. All anastomoses were patent in 16 patients. One patient had a severely stenotic RITA-to-LAD anastomosis, 13 patients had one occluded ITA anastomosis, and 2 patients had two occluded ITA anastomoses. No patient had more than two occluded anastomoses. Six of seven ITA-ITA anastomoses (strategy III, Fig 1) were patent; one free RITA-to-LITA anastomosis was occluded at 12.4 years after surgery (the distal RITA anastomoses were patent).
Anginal status at last follow-up
Of the 121 of 125 patients surviving beyond 40 days, 112 (93%) had angina at baseline. Table 3
shows that 95 of these 112 patients (85%) had no angina postoperatively at a mean of 9.1 years. None of these patients had suffered a myocardial infarction (MI) or undergone a repeat intervention.
MI-free survival
The proportion of patients without an MI after complete three-vessel CABG using only ITA grafts is shown in Figure 3.
Patients with non-MI fatality were censored at time of death. The MI freedom rates were 100% at a mean of 5 years and 97% at 10 years.
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Fig 3. This Kaplan-Meier curve shows the proportion of patients developing a myocardial infarction (MI) after complete three-vessel coronary bypass using only internal thoracic artery grafts. The four steps in the curve represent the occurrence of four MIs at those times: one at 6.5 years (patient living 6 years later at time of last follow-up), one at 7.5 years (patient died 15 months later of sudden cardiac death), one at 9.7 years (patient died 6 days later of pneumonia and congestive failure), and one at 10.5 years (patient living 3 months later at time of last follow-up). Tick marks represent the 121 censored non-MI patients comprising 57 patients dying without an MI during the observation period and 64 patients living at last follow-up. The heavy concentration of tick marks after 10 years of MI-free survival are mainly patients living at last follow-up.
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Reinterventions
Twelve patients underwent repeat vascularizations either by percutaneous transluminal coronary angioplasty (PTCA) (9 patients) or venous bypass (3 patients). There were eight PTCAs of stenotic native coronary vessels (mean of 6.8 years postoperatively). There was one PTCA of a stenotic ITA anastomosis at 1.5 years (successful). There were two vein-graft CABG procedures at 1.0 and 1.2 years after symptomatic occlusion of ITA graft anastomoses. There was one vein graft for an occluded ITA-LAD anastomosis at 8 years postoperatively in a patient without angina who was undergoing mitral repair for severe regurgitation.
Of the 121 patients surviving beyond the first 40 days, 109 (90%) did not require a reintervention procedure. The average follow-up to death or last contact of these 109 patients was 9.8 years.
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Comment
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The 85% and 87% patencies of the LITA and RITA grafts, respectively, at a mean of 7.4 years in patients undergoing angiography primarily for nonspecific chest discomfort suggest that graft patency in those patients without chest discomfort was at least as high, and possibly higher.
We have found three technical points to be important in preserving phrenic nerve function and attaining secure wound healing in the three-vessel ITA procedure. First, to minimize the possibility of injuring the phrenic nerves in the upper mediastinum, we used the bipolar cautery rather than the unipolar. Second, because the sternum is rendered partially ischemic by mobilizing both ITAs, we used as little cautery or bone wax as possible to secure sternotomy hemostasis. Third, in obese patients (especially if diabetic), we preserved a few millimeters of the distal ITA and did not incise the epigastric skin beyond the xyploid or dissect beneath it to avoid causing fat necrosis in this region. The strategy III procedure (Fig 1) facilitates these measures.
Apart from our 1985 report [2] with follow-up to 17 months in 41 patients, we know of no reports other than Tector and associates’ [1] in 2001 of exclusive three-vessel revascularization using only ITA grafts. Lytle and associates’ report in 1999 showed that two ITAs were better than one [5]. Most of their patients, however, also received supplemental vein grafts, making comparison of their large series to Tector’s or ours difficult. Our results, on the other hand, can be easily compared with those of Tector because all patients in both series received three-vessel revascularization using only ITA grafts.
Our long-term (mean of 12.1-year follow-up) results of three-vessel revascularization with only ITA grafts is similar to the midterm (mean of 4.2-year follow-up) results recently reported by Tector and associates [1]. The average age of Tector’s patients was 64.8 years (ours, 63.5 years); Tector’s follow-up percentage was 99.7% (ours, 100%); Tector’s 30-day mortality was 2.3% (our 40-day mortality was 3.2%); Tector’s 5- and 8-year survival percentages excluding the 2.3% early deaths were 86% and 75%, respectively (our survival percentages, including the four early deaths, were 84% and 71% at these times; if the early deaths were excluded, the 5- and 8-year survival percentages would be 87% and 74%); and Tector’s midterm freedom from reintervention was 95% at 5 years (our long-term freedom was 90% at 12.1 years).
Though our series is smaller than Tector’s (125 vs 897 patients), our longer-term follow-up (mean of 12.1 vs 4.2 years) with continued favorable anginal, infarction, and reintervention rates lends support to Tector’s advocacy of using ITA grafts for three-vessel revascularization to decrease the need for subsequent interventions.
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Acknowledgments
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This study was supported by The Hope Heart Institute. We are indebted to Mary Ann Sedgwick Harvey, Medical Editor; Mary-Ann Nelson, Medical Illustrator; and Eli Chiaviello, Executive Assistant to the Founder, for their essential contributions to the study and preparation of this manuscript.
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References
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- Tector A., McDonald M., Kness D., Downey F., Schmahl T. Purely internal thoracic artery grafts: outcomes. Ann Thorac Surg 2001;72:450-455.[Abstract/Free Full Text]
- Sauvage L., Wu H., Kowalsky T., et al. Healing basis and surgical techniques for complete revascularization of the left ventricle using only the internal mammary arteries. Ann Thorac Surg 1986;42:449-465.[Abstract]
- Sauvage L. Extensive myocardial revascularization using only internal thoracic arteries for grafting the anterior descending, circumflex, and right systems. Cardiac Surg State Art Rev 1992;6:397-419.
- The Criteria Committee of the New York Heart Association, Inc. Diseases of the Heart and blood vessels nomenclature and criteria for diagnosis, 6th ed Boston: Little, Brown, 1964.
- Lytle B., Blackstone E., Loop F., et al. Two internal thoracic artery grafts are better than one. J Thorac Cardiovasc Surg 1999;117:855-872.[Abstract/Free Full Text]
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Abstract
Introduction
