Arterial graft deterioration one year after coronary artery bypass grafting

Bilateral internal thoracic artery grafting: propensity analysis of the left internal thoracic artery versus the right internal thoracic artery as a bypass graft to the left anterior descending artery

OBJECTIVES

To compare different configurations of the bilateral internal thoracic arteries for the left coronary system and examine early and late outcomes, including mid-term graft patency.

METHODS

We reviewed 877 patients who underwent primary isolated coronary artery bypass grafting using in situ bilateral internal thoracic arteries [in situ right internal thoracic artery (RITA)-to-left anterior descending artery (LAD) grafting, n = 683; in situ left internal thoracic artery (LITA)-to-LAD grafting, n = 194]. We compared mid-term patency between the grafts. Propensity score matching was performed to investigate early and long-term outcomes.

RESULTS

The 2-year patency rate for RITA-to-LAD and LITA-to-LAD grafts were similar. Multivariate analysis revealed that RITA-to-non-LAD anastomosis (P = 0.029), postoperative length of stay (P = 0.003) and chronic obstructive pulmonary disease (P = 0.005) were associated with graft failure. After statistical adjustment, 176 propensity-matched pairs were available for comparison. RITA-to-LAD grafting enabled a more distal anastomosis. Kaplan-Meier analysis revealed that the incidences of death, repeat revascularization and myocardial infarction were significantly higher in the LITA-to-LAD group among both the unmatched and matched samples (P = 0.045 and 0.029, respectively).

CONCLUSIONS

The mid-term patency and outcomes of RITA-to-LAD grafting are good and reduces future cardiac event, in contrast to LITA-to-LAD grafting.

Does Moderate Coronary Stenosis Affect the Fate of the Left Internal Thoracic Artery Graft?

Introduction

In this study we try to observe the fate of the left internal thoracic artery grafts that were bypassed to left anterior descending artery with moderate stenosis identified with fractional flow reserve (FFR) technique. Doppler ultrasonography was chosen as a noninvasive screening method.

Methods

A total of 30 patients who underwent coronary artery bypass grafting depending on results of the fractional flow reserve between January 2007 and January 2012, were subjected to transthoracic color Doppler ultrasonographic evaluation irrespective of the presence of symptoms, and the presence of a systolic-diastolic flow pattern was investigated using the supraclavicular approach.

Results

The left internal thoracic artery graft was found to be functional in 63.3% of patients within a mean period of 35.1±19.7 months between coronary bypass and color Doppler ultrasonography. This period was found to be 29.4±19.6 months in the functional graft group, and 44.7±16.6 months in the dysfunctional graft group (P=0.046). Preoperative complaints of angina were reported to fall from 88.9% to 16.7% in the functional graft group, when compared to the postoperative period (P<0.001), but fell from 90.9% to 36.4% in the dysfunctional graft group (P=0.034).

Conclusion

Functional left internal thoracic artery graft rates of the study population were found to be lower than the studies reported in the literature.

Long-term patency of on- and off-pump coronary artery bypass grafting with bilateral internal thoracic arteries: the significance of late string sign development in the off-pump technique

OBJECTIVES

This study aimed to examine the effect of off-pump coronary artery bypass grafting (CABG) in patients who underwent revascularization with bilateral internal thoracic arteries (ITAs).

METHODS

Between January 2000 and December 2014, 499 patients underwent isolated CABG with bilateral ITAs for complete revascularization of the left coronary system at our institution. On-pump CABG was performed in 137 patients, and off-pump CABG was performed in 362 patients. We retrospectively compared the clinical outcomes and patency of the ITAs.

RESULTS

The off-pump group showed less respiratory failure and required a shorter postoperative stay than the on-pump group. The survival probability, freedom from cardiac events and early graft patency were similar in both groups. Five-year patency of the ITA anastomosed to the left anterior descending artery was significantly greater in the on-pump group than in the off-pump group (98.8% vs 91.2%, P = 0.010). The incidence of string change in the off-pump group was higher than that in the on-pump group (P = 0.017). There was no significant difference between the groups in the 5-year patency of the ITA anastomosed to the left circumflex artery (on-pump group: 93.8%, off-pump group: 91.8%; P = 0.46).

CONCLUSIONS

The early graft patency and the late patency of the ITA anastomosed to the left circumflex artery between the groups were similar, implying an equivalent quality of anastomoses. However, the patency of the ITA anastomosed to the left anterior descending artery in the off-pump group showed late deterioration, mainly because of string sign development.

Is the mid-term outcome of free right internal thoracic artery with a proximal anastomosis modification inferior to in situ right internal thoracic artery?

BACKGROUND

We investigated the mid-term results of free right internal thoracic artery (RITA) grafts used in an aorto-coronary fashion with a modified proximal anastomosis.

METHODS

The subjects were 214 patients who underwent coronary artery bypass grafting with anastomosis to the left circumflex arteries using the RITA as a free graft (Group A: 158 patients) or an in situ graft (Group B: 56 patients). In Group A, the proximal end of the free RITA was anastomosed onto the ascending aorta interposing free graft tissue or to part of its own tissue as a cuff.

RESULTS

The number of RITA anastomoses was 1.38 ± 0.50 in Group A and 1.04 ± 0.19 in Group B (P < 0.001). The relationship between perioperative variables and mid-term outcomes was assessed using Cox proportional hazard models. Survival was not associated with the way the RITA graft was performed (Hazard Ratio 5.26, 95 % CI 0.52-53.1, P = 0.159), however, the number of cardiac events was decreased in Group A (Hazard Ratio 2.55, 95 % CI 1.03-6.33, P = 0.043). The graft patency was evaluated in 187 of 214 patients, and at 1, 3 and 5 years was 97.0, 97.0 and 97.0 % in Group A, and 97.9, 92.5 and 80.5 % in Group B (P = 0.378), respectively.

CONCLUSION

By modifying the proximal anastomosis of the free RITA, cardiac events may be decreased, while survival and graft patency comparable with in situ RITA can be obtained, and a significantly larger number of targets can be revascularized.

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.

The right internal thoracic artery: the forgotten conduit--5,766 patients and 991 angiograms

BACKGROUND

The right internal thoracic artery (RITA) is biologically identical to the left ITA, yet is rarely used in coronary artery bypass graft surgery (CABG). We examined the results and long-term patency of RITA grafts.

METHODS

Between 1986 and 2008, 991 consecutive RITA graft angiograms for postoperative cardiac symptoms were evaluated by two independent observers. Grafts were considered nonpatent if they had a greater than 80% stenosis, string sign, or total occlusion. Patency was examined over time by coronary territory, whether in situ or free RITA, and compared with other conduits. Clinical results were collected prospectively and by the National Death Index.

RESULTS

A total of 5,766 patients had a RITA graft as part of a bilateral ITA CABG procedure. Operative mortality was 1.1%; deep sternal infection 1.5%. Of 7,780 coronary conduits studied, 991 RITA conduits were examined; a mean of 100±60 months postoperatively (1 to 288 months). Overall ten-year RITA patency was 90%. The RITA graft patency to the left anterior descending artery (LAD; n=149) was 95% at 10 years and 90% at 15 years. Ten-year RITA patency to the circumflex marginal (Cx; n=436) was 91%, right coronary artery (n=199) was 84% (p<0.001), and posterior descending artery (n=207) was 86%. Ten-year RITA and LITA patencies to the LAD were identical (95% vs 96%) and to the Cx (91% vs 89%), respectively. In situ RITA (n=450) and free RITA (n=541) had similar ten-year patencies (89% vs 91%; p=0.44). The RITA patency was always better than the radial artery (p<0.01) and saphenous vein grafts (p<0.001). Atheromatous changes were not seen in the RITA angiograms. Ten-year survival of patients with RITA and LITA for triple-vessel coronary disease was 89%.

CONCLUSIONS

Late patencies of RITA are excellent, equivalent to the LITA for identical territories, always better than radial arteries and saphenous vein grafts, and remain free of atheroma. Use of RITA in addition to LITA is associated with excellent survival in triple-vessel coronary disease. More extensive use of the RITA in CABG is recommended.

Bilateral Internal Thoracic Artery Grafting Current State of the Art

The purpose of this article is to review the key literature and assess the current status of bilateral internal thoracic artery grafting. Numerous retrospective studies have demonstrated a benefit of bilateral internal thoracic artery grafting over single internal thoracic artery grafting in terms of the long-term risk of all-cause death, cardiac-related death, and cardiac events. The survival benefit of bilateral internal thoracic artery grafting manifests relatively early after operation for high-risk patients. The skeletonization technique reduces the risk of sternal wound complications in all patients and particularly in those with diabetes. Both the left and right internal thoracic arteries have better patency when grated to the left coronary territory than saphenous vein. However, the right internal thoracic artery does not always have good patency when grafted to the right coronary artery. Bilateral internal thoracic artery grafting using the skeletonization technique is recommended for revascularization of the left coronary territory.