HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Chang Young Kim Dong Soo Lee Ki-Bong Kim Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kim, C. Y. Articles by Kim, K.-B. Search for Related Content PubMed PubMed Citation Articles by Kim, C. Y. Articles by Kim, K.-B. Related Collections Coronary disease

---

Original Articles: Adult Cardiac

Improved Myocardial Perfusion and Thickening After Off-Pump Revascularization: 5-Year Follow-Up

^a Department of Thoracic and Cardiovascular Surgery, Ilsan Paik Hospital, College of Medicine, Inje University, Go-yang, South Korea
^b Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Seoul, South Korea
^c Department of Nuclear Medicine, Seoul National University Hospital, Seoul, South Korea

Accepted for publication July 2, 2009.

^_* Address correspondence to Dr Ki-Bong Kim, Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, 28 Yeongeon-dong, Chongno-gu, Seoul, 110-744, South Korea (Email: kimkb{at}snu.ac.kr).

	Abstract

Top Abstract Introduction Patients and Methods Results Comment References

 
Background: Late improvements in myocardial perfusion and thickening after off-pump revascularization were evaluated during a 5-year follow-up by myocardial single photon emission computed tomography.

Methods: Between 2001 and 2003, 68 patients who underwent off-pump coronary artery bypass grafting using bilateral internal thoracic artery Y-composite (group Y, n = 41) or in situ (group I, n = 27) grafts for revascularization of the left coronary artery territory were enrolled. Myocardial single photon emission computed tomography was performed preoperatively and at 3 months, 1 year, and 5 years postoperatively. A 20-segment model was adopted. As an indicator of ischemic myocardium, the reversibility score was defined as a measure of rest minus stress perfusion values. A total of 374 segments that showed a reversibility score of 7 preoperatively were included. Z values for thickening were calculated as observed values minus reference values divided by the reference standard deviation. Mixed-model analysis was used to compare the two groups with respect to the time sequences of myocardial reversibility scores and Z values.

Results: Postoperative reversibility scores improved significantly at 3 months (p < 0.001) and further at 5 years (p = 0.030). Postoperative Z values improved significantly at 3 months (p < 0.001), between 1 year and 5 years (p = 0.006), and further at 5 years (p = 0.004). In the mixed models, there were no significant differences in reversibility scores and Z values between groups Y and I at any point.

Conclusions: Reversibility scores and thickening gradually improved during 5 years after off-pump revascularization using bilateral internal thoracic arteries. No significant differences were observed between Y-composite and bilateral in situ grafts in terms of reversibility score and thickening improvement at 5 years postoperatively.

	Introduction

Top Abstract Introduction Patients and Methods Results Comment References

 
The use of the left internal thoracic artery (ITA) for grafting of the left anterior descending artery with supplemental saphenous vein grafts became the standard coronary artery bypass grafting (CABG) technique on the basis of reports of superior graft patency, reduced cardiac events, decreased need for reintervention, and enhanced long-term survival when compared with patients receiving only vein grafts [1, 2]. The widely accepted success of the left ITA has led to the use of both ITAs. The use of two ITAs instead of one has also demonstrated advantages, such as greater freedom from reinterventions and enhanced long-term survival rates in surgical revascularization for multivessel coronary artery disease [3–5]. For bilateral ITA grafting in an in situ or Y-composite configuration is used; however, the superiority of one method over the other has not been established. The use of bilateral ITAs as in situ grafts has the presumptive advantage that multiple blood sources may be more favorable than a single blood source for improving long-term outcome. However, there is a concern that construction of an ITA Y-composite graft may not supply sufficient blood flow to a wider area of myocardium because it emanates from a single blood source [6, 7].

Myocardial single photon emission computed tomography (SPECT) has been shown to be an effective modality for identifying myocardial viability, guiding appropriate management, and evaluating the improvement of myocardial stress perfusion after revascularization [8, 9].

The aims of this study were (1) to evaluate late improvements in myocardial perfusion and thickening after off-pump coronary artery bypass grafting (OPCAB) using bilateral ITAs, and (2) to compare the time course of myocardial perfusion and thickening improvement for bilateral ITA Y-composite and in situ grafts during 5 years of follow-up by myocardial SPECT.

	Patients and Methods

Top Abstract Introduction Patients and Methods Results Comment References

 
The study protocol was reviewed by the institutional review board and approved as a minimal risk retrospective study (approval no. H-0712-004-227) that did not require individual consent according to the institutional guidelines for waiving consent.

Of 452 patients who underwent OPCAB between January 2001 and December 2003, we retrospectively studied 68 patients who underwent myocardial SPECT preoperatively, and at 3 months, 1 year, and 5 years postoperatively. Myocardial SPECT was performed as part of the routine clinical follow-up, and postoperative 5-year (61 ± 5 months) coronary angiography was performed regardless of anginal symptoms. Inclusion criteria included (1) patients who underwent myocardial revascularization during OPCAB; (2) patients who received bilateral skeletonized ITAs as either Y-composite or in situ grafts to completely revascularize the left coronary territory; (3) patients with a graft patency confirmed by coronary angiography performed at 5 years postoperatively; and (4) patients in whom both resting and stress myocardial SPECT were performed preoperatively and at 3 months, 1 year, and 5 years postoperatively. Patients who received other arterial grafts or free grafts anastomosed on the ascending aorta to revascularize the left coronary artery territory, and patients who did not receive stress myocardial SPECT preoperatively because of intractable resting angina or an urgent or emergency situation were excluded. Bilateral ITAs were used as Y-composite grafts (group Y) in 41 patients and as in situ grafts (group I) in 27 patients. No differences were observed between the two study groups in terms of sex, age, preoperative risk factors (except hypertension and left ventricular ejection fraction), the ratio of unstable to stable angina, or angiographic diagnoses (Table 1). Group Y had a higher left ventricular ejection fraction than group I by transthoracic echocardiography (0.61 ± 0.10 versus 0.54 ± 0.10; p = 0.011) and myocardial SPECT (0.55 ± 0.12 versus 0.46 ± 0.18; p = 0.016).

Myocardial Single Photon Emission Computed Tomography Testing
Thallium 201 rest/dipyridamole stress technetium 99m methoxyisobutylisonitrile (MIBI)–gated SPECT was performed. Briefly, ²⁰¹Tl (111 MBq) was injected at rest, and SPECT was performed. Coronary perfusion reserve was then assessed by injecting dipyridamole (0.56 mg/kg) for more than 4 minutes to induce stress, and ^99mTc (925 MBq) was injected 3 minutes after stress. Gated ^99mTc-MIBI SPECT was performed 90 minutes after stress using a dual-head camera equipped with a low-energy, high-resolution collimator (Vertex EPIC; ADAC Laboratories, Milpitas, CA). This procedure was repeated at 3 months (99 ± 9 days), 1 year (15 ± 3 months), and 5 years (62 ± 6 months) postoperatively.

Quantification of Myocardial Regional Perfusion and Thickening
After overall image quality was assessed by two experts, reconstructed images were analyzed using an automatic quantifying software package (AutoQUANT; ADAC Laboratories) without manual intervention. A 20-segment model was adopted for regional analysis. Each segment was subtended to two coronary arterial territories (right and left coronary artery territories), and all 16 segments representing the left coronary artery territory (left anterior descending artery and left circumflex artery territories) were analyzed as a whole (Fig 1). Segments representing the right coronary artery territory were excluded. Resting and stress segmental myocardial perfusions were quantified by measuring radioactivity, and were expressed as percentages of maximal radioactivity uptake. It was presumed that segments with a preoperative resting perfusion of 50% or less contained less viable myocardium and more fibrotic or necrotic myocardium than segments with a resting perfusion of greater than 50% [11, 12]. Therefore, probable nonviable segments with a preoperative resting perfusion of 50% or less were excluded from this study. Reversibility score, an indicator of perfusion impairment reversibility, was calculated as rest minus stress perfusion values in each segment. To select perfusion-impaired segments in the left coronary artery territory, a reversibility score cutoff of 7 was used [13]. Segmental myocardial thickening, presented as percentages, was quantified by measuring systolic increments in myocardial thickness. Because segmental thickening values are different, Z values for thickening, defined as observed values minus reference values, then divided by the standard deviation of reference values, were used [14].

View larger version (37K): [in this window] [in a new window]   Fig 1. A 20-segment model. (LAD = left anterior descending coronary artery; LCX = left circumflex coronary artery; RCA = right coronary artery.)

	Results

Top Abstract Introduction Patients and Methods Results Comment References

 
Operative Results
Average numbers of distal anastomoses per patient and per bilateral ITAs were 3.1 ± 0.8 and 2.5 ± 0.6, respectively. No significant differences were observed between the two groups with respect to the average number of distal anastomoses per patient (3.1 ± 0.9 in group Y versus 3.0 ± 0.6 in group I; p = 0.358) and per bilateral ITAs (2.6 ± 0.7 in group Y versus 2.4 ± 0.5 in group I; p = 0.355) or the number of patients with sequential anastomoses (48.8%, 20 of 41 versus 44.4%, 12 of 27; p = 0.806). There were no significant intergroup differences regarding the incidence of postoperative morbidities, such as atrial fibrillation (26.9%, 11 of 41 versus 14.8%, 4 of 27; p = 0.371), perioperative myocardial infarction (2.4%, 1 of 41 versus 3.7%, 1 of 27; p = 1.000), and reoperation for bleeding (7.3%, 3 of 41 versus 3.7%, 1 of 27; p = 1.000). We did not experience any low cardiac output syndrome, acute renal failure, mediastinitis, or stroke in either group.

Myocardial Single Photon Emission Computed Tomography Test
A total of 402 segments (256 segments in group Y, 146 segments in group I) showed a reversibility score of 7 or greater preoperatively. To choose reliable viable segments, probable nonviable segments with a preoperative resting perfusion of 50% or less (12 segments in group Y, 16 segments in group I) were excluded [11]. Group Y had a smaller proportion of nonviable segments than group I (4.7%, 12 of 256 versus 11.0%, 16 of 146; p = 0.024; Table 2). For all 374 segments, postoperative reversibility scores improved significantly at 3 months (14.8 ± 6.7 versus 3.9 ± 7.9; p < 0.001) and were further improved at 5 years (3.9 ± 7.9 versus 2.6 ± 8.5; p = 0.030). Postoperative Z values improved significantly at 3 months (–1.62 ± 1.49 versus –0.93 ± 1.59; p < 0.001), between 1 year and 5 years (–0.89 ± 1.34 versus –0.61 ± 1.38; p = 0.006), and were further improved at 5 years (–0.93 ± 1.59 versus –0.61 ± 1.38; p = 0.004). In group Y, postoperative Z values improved significantly at 3 months (–1.41 ± 1.43 versus –0.88 ± 1.43; p < 0.001), between 1 year and 5 years (–0.84 ± 1.18 versus –0.46 ± 1.25; p < 0.001), and were further improved at 5 years (–0.88 ± 1.43 versus –0.46 ± 1.25; p < 0.001). On the other hand, postoperative Z values improved significantly at 3 months (–2.03 ± 1.54 versus –1.01 ± 1.85; p < 0.001) but showed no significant improvement thereafter in group I (Fig 2). In group Y, irrespective of preoperative Z values, and in group I for preoperative Z values of –2.0 or less, postoperative Z values improved significantly at 3 months and were further improved at 5 years. In group I members with a preoperative Z value of greater than –2.0, postoperative Z values improved significantly at 3 months (–0.90 ± 0.81 versus –0.04 ± 1.60; p < 0.001) but showed no subsequent improvement (Figs 3, 4).

View larger version (33K): [in this window] [in a new window]   Fig 2. Reversibility scores and thickening Z values. The central box represents the values from the lower to upper quartile (25 to 75 percentile) and the middle line represents the median. A line extends from the minimum to the maximum value. *p < 0.0167, **p < 0.05. (Pre = preoperative.)

View larger version (24K): [in this window] [in a new window]   Fig 3. Comparisons of subgroups with preoperative Z values –2.0. *p < 0.0167, **p < 0.05. (Pre = preoperative.)

View larger version (23K): [in this window] [in a new window]   Fig 4. Comparisons of subgroups with preoperative Z values > –2.0. *p < 0.0167, **p < 0.05. (Pre = preoperative.)

	Comment

Top Abstract Introduction Patients and Methods Results Comment References

Greater freedom from reinterventions and enhanced long-term survival rates have been demonstrated when bilateral ITAs are used rather than a single ITA graft in surgical revascularization for multivessel coronary artery disease [3–5]. For bilateral ITA graftings in an in situ or Y-composite configuration, however, the superiority of one method versus the other has not been established. The use of bilateral ITAs as in situ grafts has the presumptive advantage that multiple blood sources may be more favorable than a single blood source for improving long-term outcome [6, 7], although the length of the right ITA is the main limitation in bilateral in situ ITA grafting. However, construction of a composite graft, such as a Y or T graft, increases the length of the ITA, and allows the extensive use of bilateral ITA grafts to revascularize the left coronary artery system as well as the right coronary artery system [10, 15]. There is a concern that because the composite graft only emanates from a single blood source, it may not supply sufficient blood flow to a wider area of myocardium [6, 7]. The skeletonization technique for harvesting the ITA has been shown to increase free-flow capacity [16], and the left ITA in a Y-composite graft has been shown to adapt its dimensions to flow demand immediately postoperatively [17]. In the present study, despite the assumption that two blood sources would provide better long-term outcomes than a single source, Y-composite grafts using skeletonized ITAs were constructed if the left coronary artery territory could not be completely revascularized with bilateral in situ ITA grafts.

In the present study, there were some baseline differences between the two groups. Group Y had a higher left ventricular ejection fraction (p < 0.05). In addition, because preoperative Z values between the two groups (p < 0.001) and interaction between the graft arrangement and follow-up period (p = 0.021) showed significant differences, these factors were included in the mixed-model analysis of the Z values. There were no significant differences between the two groups in comparisons of the time sequences of myocardial reversibility scores and Z values by using a mixed-model analysis. The present study divided each group into two subgroups based on preoperative thickening using a Z value cutoff of –2.0, based on the assumption that greater reductions in segmental thickening preoperatively would achieve greater thickening improvements after revascularization [18].

A previous study [9] demonstrated that postoperative myocardial reversibility scores improved substantially during the first 3 months and further improved until 1 year, and that perfusion improvements were similar for Y-composite and bilateral in situ ITA grafts in terms of reversibility scores. The present study also demonstrated that postoperative reversibility scores of whole segments improved during the first 3 months (p < 0.001) and further improved up to 5 years (p = 0.030), although no significant differences were observed between 3 months and 1 year. There are several explanations for long-term improvements in postoperative reversibility scores: (1) microcirculation improvements, associated with de novo vessel formation by endothelial progenitor cells (vasculogenesis) and with the development of new collateral vessels from established vascular networks (angiogenesis) after the restoration of blood flow into ischemic regions [19]; and (2) the overall effects of early and long-standing improvements in stress perfusion and early overcorrected and gradually normalized resting perfusion, which occurred in segments with enhanced perfusion under conditions of impaired autoregulation and endothelial dysfunction during the early postoperative period, such as cerebral hyperperfusion syndrome after carotid endarterectomy [20]. Interestingly, these "early-hyperperfused and gradually-normalized resting perfusion" patterns were obvious in group I.

The present study also assessed segmental thickening by measuring systolic increments of myocardial thickness, which could reflect a segmental contractility by definition. Z values of thickening were calculated to compare thickening improvements indirectly owing to different normal values of segmental thickening. We adopted reference values for segmental thickening [14]. Improvements in Z values in groups Y and I showed no significant differences in mixed-model analysis. In group I, postoperative Z values improved significantly at 3 months (p < 0.001); however, no further significant improvement was observed thereafter. This was particularly prominent in segments with a preoperative Z value of greater than –2.0. Functional recovery took more than 1 year in some segments, particularly in severely dysfunctional segments with preoperative Z values of less than –2.0. Most patients with ischemic cardiomyopathy have a mixture of stunned, hibernating, remodeled, and nonviable myocardium [21, 22] and may therefore show variable degrees and timings of functional improvement after revascularization depending on the preoperative ratios of these components [23]. Although myocardial thickening is not an absolute criterion for the assessment of hibernating myocardium, segments with higher preoperative thickening (Z value > –2.0), which may have included relatively less hibernating and more stunned myocardium, have been reported to show an earlier recovery pattern after coronary revascularization than segments with a lower Z value [24].

Some limitations of the present study must be recognized. First, this study was not performed in a randomized manner because randomized controlled trials on this topic are often unrealistic and impractical. Although the number of enrolled patients was relatively small and patients were not randomized, all experiences at one institution were collected using a computer-based database system. Second, because we adopted a 20-segment model for regional analysis and analyzed all 16 segments representing the left coronary artery territory, individual coronary artery dominance patterns were not considered. Third, segmental thickening Z values were used to analyze improvements in segmental contractility; however, segmental thickening improvements may not reflect improvements in individual cardiac function. Finally, graft patency was confirmed at 5 years postoperatively, but progression or new development of native coronary artery diseases were not considered in the analysis.

	References

Top Abstract Introduction Patients and Methods Results Comment References

 

1. Loop FD, Lytle BW, Cosgrove DM, et al. Influence of the internal-mammary-artery graft on 10-year survival and other cardiac events N Engl J Med 1986;314:1-6.[Medline]
2. Cameron A, Davis KB, Green G, Schaff HV. Coronary bypass surgery with internal-thoracic-artery grafts: effects on survival over a 15-year period N Engl J Med 1996;334:216-220.[Medline]
3. Buxton BF, Komeda M, Fuller JA, Gordon I. Bilateral internal thoracic artery grafting may improve outcome of coronary artery surgery. Risk-adjusted survival. Circulation 1998;98(Suppl 2):II-1-II-6.
4. Lytle BW, Blackstone EH, Loop FD, et al. Two internal thoracic artery grafts are better than one J Thorac Cardiovasc Surg 1999;117:855-872.[Abstract/Free Full Text]
5. Stevens LM, Carrier M, Perrault LP, et al. Single versus bilateral internal thoracic artery grafts with concomitant saphenous vein grafts for multivessel coronary artery bypass grafting: effects on mortality and event-free survival J Thorac Cardiovasc Surg 2004;127:1408-1415.[Abstract/Free Full Text]
6. Lev-Ran O, Paz Y, Pevni D, et al. Bilateral internal thoracic artery grafting: midterm results of composite versus in situ crossover graft Ann Thorac Surg 2002;74:704-711.[Abstract/Free Full Text]
7. Sakaguchi G, Tadamura E, Ohnaka M, Tambara K, Nishimura K, Komeda M. Composite arterial Y graft has less coronary flow reserve than independent grafts Ann Thorac Surg 2002;74:493-496.[Abstract/Free Full Text]
8. Travin MI, Bergmann SR. Assessment of myocardial viability Semin Nucl Med 2005;35:2-16.[Medline]
9. Cho KR, Hwang HY, Kang WJ, Lee DS, Kim K-B. Progressive improvement of myocardial perfusion after offpump revascularization with bilateral internal thoracic arteries: comparison of early versus 1-year postoperative myocardial single photon emission computed tomography J Thorac Cardiovasc Surg 2007;133:52-57.[Abstract/Free Full Text]
10. Kim K-B, Cho KR, Chang W-I, Lim C, Ham BM, Kim YL. Bilateral skeletonized internal thoracic artery graftings in off-pump coronary artery bypass: early result of Y versus in situ grafts Ann Thorac Surg 2002;74(Suppl):1371-1376.
11. Perrone-Filardi P, Pace L, Prastaro M, et al. Dobutamine echocardiography predicts improvement of hypoperfused dysfunctional myocardium after revascularization in patients with coronary artery disease Circulation 1995;91:2556-2565.[Abstract/Free Full Text]
12. Ragosta M, Beller GA, Watson DD, Kaul S, Gimple LW. Quantitative planar rest-redistribution ²⁰¹Tl imaging in detection of myocardial viability and prediction of improvement in left ventricular function after coronary bypass surgery in patients with severely depressed left ventricular function Circulation 1993;87:1630-1641.[Abstract/Free Full Text]
13. Paeng JC, Lee DS, Cheon GJ, et al. Consideration of perfusion reserve in viability assessment by myocardial Tl-201 rest-redistribution SPECT: a quantitative study with dual-isotope SPECT J Nucl Cardiol 2002;9:68-74.[Medline]
14. Sharir T, Berman DS, Waechter PB, et al. Quantitative analysis of regional motion and thickening by gated myocardial perfusion SPECT: normal heterogeneity and criteria for abnormality J Nucl Med 2001;42:1630-1638.[Abstract/Free Full Text]
15. Calafiore AM, Contini M, Vitolla G, et al. Bilateral internal thoracic artery grafting: long-term clinical and angiographic results of in situ versus Y grafts J Thorac Cardiovasc Surg 2000;120:990-998.[Abstract/Free Full Text]
16. Wendler O, Tscholl D, Huang Q, Schafers HJ. Free flow capacity of skeletonized versus pedicled internal thoracic artery grafts in coronary artery bypass grafts Eur J Cardiothorac Surg 1999;15:247-250.[Abstract/Free Full Text]
17. Lemma M, Innorta A, Pettinari M, et al. Flow dynamics and wall shear stress in the left internal thoracic artery: composite arterial graft versus single graft Eur J Cardiothorac Surg 2006;29:473-478.[Free Full Text]
18. Rizzello V, Biagini E, Schinkel AFL, et al. Comparison of functional recovery of mildly hypokinetic versus severely dysfunctional left ventricular segments after revascularization in patients with ischemic cardiomyopathy Am J Cardiol 2004;93:394-398.[Medline]
19. Carmeliet P. Angiogenesis in health and disease Nat Med 2003;9:653-660.[Medline]
20. van Mook WNKA, Rennenberg RMW, Schurink GW, et al. Cerebral hyperperfusion syndrome Lancet Neurol 2005;4:877-888.[Medline]
21. Narula J, Dawson MS, Singh BK, et al. Noninvasive characterization of stunned, hibernating, remodeled and nonviable myocardium in ischemic cardiomyopathy J Am Coll Cardiol 2000;36:1913-1919.[Abstract/Free Full Text]
22. Hughes GC, Landolfo CK, Yin B, et al. Is chronically dysfunctional yet viable myocardium distal to a severe coronary stenosis hypoperfused? Ann Thorac Surg 2001;72:163-168.[Abstract/Free Full Text]
23. Shivalkar B, Maes A, Borgers M, et al. Only hibernating myocardium invariably shows early recovery after coronary revascularization Circulation 1996;94:308-315.[Abstract/Free Full Text]
24. Haas F, Jennen L, Heinzmann U, et al. Ischemically compromised myocardium displays different time-course of functional recovery: correlation with morphological alterations? Eur J Cardiothorac Surg 2001;20:290-298.[Abstract/Free Full Text]

This article has been cited by other articles:

				H. Nakajima, J. Kobayashi, K. Toda, T. Fujita, Y. Shimahara, Y. Kasahara, and S. Kitamura Angiographic evaluation of flow distribution in sequential and composite arterial grafts for three vessel disease Eur J Cardiothorac Surg, December 21, 2011; (2011) ezr057v1. [Abstract] [Full Text] [PDF]

				H. Y. Hwang, J. S. Kim, K. R. Cho, and K.-B. Kim Bilateral Internal Thoracic Artery In Situ Versus Y-Composite Graftings: Five-Year Angiographic Patency and Long-Term Clinical Outcomes Ann. Thorac. Surg., August 1, 2011; 92(2): 579 - 586. [Abstract] [Full Text] [PDF]

				K.-B. Kim Invited Commentary Ann. Thorac. Surg., March 1, 2010; 89(3): 687 - 688. [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Chang Young Kim Dong Soo Lee Ki-Bong Kim Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kim, C. Y. Articles by Kim, K.-B. Search for Related Content PubMed PubMed Citation Articles by Kim, C. Y. Articles by Kim, K.-B. Related Collections Coronary disease