Late improvement in graft patency after coronary artery bypass grafting: Serial assessment with multidetector computed tomography in the early and late postoperative settings

Acute coronary syndrome due to native coronary occlusion proximal to a patent bypass graft: a case report

Background

Primary percutaneous coronary intervention (PCI) for acute coronary syndrome has significantly contributed to improvements in overall outcomes. However, clinical challenges exist when performing urgent PCI for patients with a history of coronary artery bypass grafting (CABG).

Case summary

An 83-year-old man with a history of CABG presented with an inferior ST-elevation myocardial infarction (STEMI). Emergent coronary angiography showed an occlusion of the right coronary artery that had been previously grafted with the right gastroepiploic artery. Primary PCI for the native coronary artery was performed on the assumption that the bypass graft had been occluded. We were unable to attain angiographic antegrade flow after balloon angioplasty, and intravascular ultrasound revealed a ruptured plaque with a thrombus proximally and a patent bypass graft with complete recanalization distally. These findings suggested that the plaque rupture with resultant thrombus formation proximal to the anastomosis eventually overlay the patent bypass graft. Subsequent stent implantation covering only the culprit site with a residual stenosis proximal to the anastomosis was performed, resulting in good patency of both the native coronary artery and bypass graft for more than 3 years.

Discussion

This is the first documented case of a patient with STEMI due to proximal native coronary artery occlusion with a thrombus overlying a patent bypass graft. Intravascular ultrasound was helpful to recognize the distal patency and guide optimal stent implantation. This case illustrates the complexity of treating a patient with a history of CABG and the importance of a multifaceted approach in such an urgent situation.

Functional Recovery of a Failed Radial Artery Graft After Progression of Native Coronary Stenosis

Competitive flow from the native vessel can lead to coronary graft failure. However, restoration of graft patency can occasionally occur. We present the case of subtotal occlusion of a radial artery graft bypassing a lesion with moderate stenosis, with subsequent late functional recovery once the native vessel disease had progressed. (Level of Difficulty: Intermediate.).

Sequential Versus Individual Saphenous Vein Grafting During Coronary Arterial Bypass Surgery

BACKGROUND

Although multiarterial grafting or bilateral mammary artery use is being increasingly emphasized for contemporary coronary artery bypass grafting (CABG) practice, saphenous vein graft (SVG) is still the most frequently used CABG conduit, and it accounts for 80% of all CABG conduits. Research focusing on modifiable surgical factors such as anastomosis technique, however, is scarce. This study aimed to compare clinical outcomes and graft patency according to anastomosis methods of vein grafting.

METHODS

From January 2005 through December 2016, patients who underwent CABG using SVG either by a sequential or an individual grafting technique were enrolled in this study. Graft patency was evaluated with coronary computed tomographic angiography. Propensity-score matching was used to compare the clinical outcomes and graft patency of these 2 grafting techniques to reduce treatment selection bias.

RESULTS

Overall 2515 eligible patients, 1,037 in the sequential SVG graft group (41.3%) and 1478 (58.8%) in the individual SVG graft group were enrolled. After propensity-score matching, 901 matched pairs of patients and 891 matched pairs of grafts were included in the final outcome analysis. There were no significant differences in unadjusted (P = .83) and adjusted overall mortality (hazard ratio [HR], 0.96; 95% confidence interval [CI], 0.79 to 1.17; P = .67). The composite outcome of death, nonfatal myocardial infarction, and repeat revascularization also did not significantly differ between the sequential SVG and the individual SVG groups for both before (P = .20) and after matching (HR, 0.91; 95% CI, 0.75 to 1.09; P = .30). The sequential grafts showed superior patency as compared with the individual grafts for both before (P = .015) and after adjustment (HR, 0.61; 95% CI, 0.45 to 0.82; P < .001).

CONCLUSIONS

The sequential grafting technique of SVG showed fairly acceptable safety and efficacy with superior long-term graft patency than individual grafts. Sequential SVG grafts perhaps can be a reasonable option as a second graft in CABG in some clinical situations.

Fate of Grafts Bypassing Nonischemic Versus Ischemic Inducing Coronary Stenosis

There is a lack of evidence regarding the efficacy of ischemia-guided coronary artery bypass grafting. We compared the incidence of graft failure between grafts bypassing ischemia-inducing and nonischemia-inducing stenoses. Between 1997 and 2011, 2,304 patients for whom baseline coronary angiography and myocardial perfusion imaging were available were identified from a single-center coronary artery bypass grafting registry. According to baseline myocardial perfusion imaging, each graft was assigned to either graft bypassing ischemia-inducing or nonischemia-inducing stenoses (ischemia-related grafts, n = 4,904; ischemia-unrelated grafts, n = 2,709). Graft failure was defined as total occlusion on coronary computed tomography angiography, performed at the discretion of the treating physician. The incidence of graft failure was compared on a per-graft basis. At 5 years, the incidence of graft failure was significantly higher in the ischemia-unrelated grafts (4.2% vs 2.9% in ischemia-related grafts; p = 0.003). Ischemia-related graft was an independent determinant of graft patency (adjusted hazard ratio 0.61; 95% confidence interval 0.44 to 0.84; p = 0.002). Increased risk of graft failure associated with ischemia-unrelated graft was observed only in the internal thoracic artery (3.3% vs 2.0%, p = 0.021) and arterial grafts (6.5% vs 4.3%, p = 0.020), but not in the venous grafts (2.7% vs 2.7%; p = 0.99). In terms of major adverse cardiac and cerebrovascular events, 5-year incidences were comparable between the patients with and without ischemia-unrelated grafts (219, 19.3% vs 160, 18.0%; p = 0.61). In conclusion, ischemia-unrelated grafts became dysfunctional more frequently than ischemia-related grafts, and were not preventive of adverse events.

Comparison of graft patency following coronary artery bypass grafting in the left versus the right coronary artery systems: a systematic review and meta-analysis

Although coronary artery bypass grafting has been the standard of care for patients with complex coronary artery disease for over 50 years, the evolution of graft patency over time in the left versus the right coronary systems remains poorly documented. This systematic review and meta-analysis aimed to characterize the evolution of graft patency over time comparing the left (excluding left anterior descending artery) and right coronary systems, with an emphasis on the comparison of venous versus arterial grafts and symptomatic versus asymptomatic patients. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) and MEDLINE from inception to August 2016. We also searched clinical trials registers and reference lists of relevant studies. We included randomized clinical trials and observational studies comparing graft patency in the left versus the right coronary systems. Our outcome was graft patency defined as a binary variable according to whether grafts were reported as patent or failed at the time of angiogram. Data collection and analysis were performed according to the methodological recommendations of the Cochrane Collaboration. From a total 2275 papers, 52 studies were included in the qualitative analysis and 48 studies (including 36 006 grafts) in the meta-analysis. There was a 3.3% significant difference between the left-sided and right-sided graft patency, and the difference appeared to increase over time. Furthermore, patency of arterial grafts was higher in the left coronary system, while venous grafts performed similarly irrespective of the coronary circulation. Symptom recurrence also seemed related to a higher failure rate in the right coronary circulation. However, the high degree of heterogeneity precluded drawing definite conclusions. This meta-analysis suggested that graft patency might be better for left-sided vessels and that this difference might be driven by the better performance of arterial grafts in the left coronary system. However, evidence currently available is limited, and further research is warranted to understand whether certain grafts achieve better patency in the right versus the left coronary circulations.

Relationship between Serum Uric Acid Concentration and Acute Kidney Injury after Coronary Artery Bypass Surgery

An elevated serum concentration of uric acid may be associated with an increased risk of acute kidney injury (AKI). The aim of this study was to investigate the impact of preoperative uric acid concentration on the risk of AKI after coronary artery bypass surgery (CABG). Perioperative data were evaluated from patients who underwent CABG. AKI was defined by the AKI Network criteria based on serum creatinine changes within the first 48 hr after CABG. Multivariate logistic regression was utilized to evaluate the association between preoperative uric acid and postoperative AKI. We evaluated changes in C statistic, the net reclassification improvement, and the integrated discrimination improvement to determine whether the addition of preoperative uric acid improved prediction of AKI. Of the 2,185 patients, 787 (36.0%) developed AKI. Preoperative uric acid was significantly associated with postoperative AKI (odds ratio, 1.18; 95% confidence interval, 1.10-1.26; P<0.001). Adding uric acid levels improved the C statistic and had significant impact on risk reclassification and integrated discrimination for AKI. Preoperative uric acid is related to postoperative AKI and improves the predictive ability of AKI. This finding suggests that preoperative measurement of uric acid may help stratify risks for AKI in in patients undergoing CABG.

Association of prediabetes with diffuse coronary narrowing and small-vessel disease

BACKGROUND

A significant number of patients may not benefit from conventional techniques of myocardial revascularization due to diffuse coronary artery disease (CAD) or small coronary arterial sizes because of smaller arteries causing anastomotic technical difficulties and poor run-off. Diabetic patients have a more severe and diffuse coronary atherosclerosis with smaller coronary arteries limiting the possibility to perform a successful and complete revascularization, but this has not been examined in prediabetics.

OBJECTIVE

To evaluate whether there is an association between prediabetes and the coronary arterial size.

METHODS

We prospectively studied 168 consecutive patients with CAD and 172 patients with normal coronary artery anatomy (NCA). Patients were divided into three groups according to hemoglobin (Hb) A1c levels as "normal," "prediabetic," and "diabetic" groups, and the coronary artery sizes and Gensini scores were analyzed.

RESULTS

There were 78 female patients and 90 male patients in the CAD group, and 87 female patients and 85 male patients in the NCA group. There was a statistically significant difference in distal and proximal total coronary arterial size among the CAD and NCA groups for both genders. There was a positive correlation between the HbA1c subgroups and Gensini score (Spearman's ρ: 0.489, p<0.001 in female group; Spearman's ρ: 0.252 p=0.016 in male group).

CONCLUSION

We found that prediabetic patients have a smaller coronary size and diffuse coronary narrowing for both genders, particularly in distal coronary arterial tree of left anterior descending coronary artery. The early detection of prediabetes in daily cardiology practice may provide more appropriate coronary lesion for percutaneous or surgical revascularization.

Computerized tomography may underestimate the patency of internal thoracic artery composite grafts

BACKGROUND

Multidetector-row computerized tomography (MDCT) has been regarded as useful for noninvasive assessment of the bypass grafts after coronary artery bypass grafting (CABG), but there have been few reports validating its accuracy in assessment of composite arterial graft patency.

METHODS

In 108 patients who underwent CABG with a Y-composite graft made of bilateral internal thoracic arteries (ITAs), early postoperative (mean interval, 4.9 months) MDCT findings were compared with the findings of subsequent conventional coronary angiography (19 patients, mean 4.7 months after initial MDCT) or later MDCT (89 patients, mean 31.0 months after surgery). A total of 248 grafts with 409 distal anastomoses (mean 3.8/patient) were assessed.

RESULTS

In the early MDCT, the left ITA was patent in 94.4%. The right ITA with multiple sequential anastomoses was completely patent in 73.8% and partially patent in 21.4%. Discrepancy of findings between early computed tomography (CT) and later imaging studies was found in 18 patients (16.7%). Fourteen (42.4%, 4 left and 10 right ITAs) among the 33 initially nonvisualized grafts showed improved patency in later MDCT or conventional angiogram. The positive predictive value of the early MDCT for ITA composite graft occlusion was calculated at 57.6% or lower, whereas the negative predictive value was 97.8% or higher.

CONCLUSIONS

For a composite graft made of bilateral ITAs, especially for those with multiple sequential anastomoses, MDCT may reflect only the functional patency and underestimate the actual anatomic patency.