Total arterial revascularization is associated with long-term survival benefit in coronary artery bypass grafting: systematic review with meta-analysis

Importance

Total arterial revascularization (TAR), the complete avoidance of saphenous vein grafting (SVG) in coronary artery bypass grafting (CABG), is advocated based on the superior conduit durability and resistance against atherosclerosis. However, the low adoption rate of TAR indicates a high level of controversy.

Objective

To compare long-term survival between TAR and conventional CABG involving SVG.

Data sources

A comprehensive literature search was conducted through digital databases including MEDLINE, Embase, and Cochrane Central Register of Controlled Trials from the inception to May 2021.

Study selection

The inclusion criteria were randomized clinical trials, or propensity-score balanced or multivariable-adjusted observational studies with a sample size of at least 100 patients in each arm, isolated CABG, comparing TAR (SVG=0) vs. non-TAR (SVG≥1), and inclusion of all-cause mortality.

Data extraction and synthesis

Two reviewers performed independent extraction following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Pooled hazard ratios (HR) and 95% confidence intervals (CI) were estimated with random-effect and fixed-effect models using generic inverse variance weighting. Individual patient time-to-event data were reconstructed to create an overall Kaplan-Meier survival function for matched studies. Sensitivity analyses were performed according to the risk of bias, matching status, and source of HR.

Main outcomes and measures

The primary endpoint was all-cause mortality.

Results

A total of 23 studies (100,314 patients), all with a retrospective observational design, were identified. The weighted mean follow-up time was 8.8 years post-operatively. Total arterial revascularization was associated with greater freedom from all-cause mortality than non-TAR (HR, 0.77, 95% CI, 0.71 to 0.84, p<0.001). There was evidence of low heterogeneity (I2=45%) across studies. Low publication bias was observed. Leave-one-out influence analysis and sensitivity analyses produced consistent results. Cochrane Collaboration signaling domains showed no critical risk of bias.

Conclusions and relevance

This meta-analysis found superior late survival associated with total arterial revascularization. Further randomized clinical trials are needed.

Funding Acknowledgement

Type of funding sources: None.

1657 Systematic Review and Meta-Analysis of Mortality Risk Prediction Models in Adult Cardiac Surgery

Background

The most used mortality risk prediction models in cardiac surgery are the European System for Cardiac Operative Risk Evaluation(EuroSCORE)(ES) and Society of Thoracic Surgeons(STS) score. There is no agreement on which score should be considered more accurate nor which score should be utilised in each population sub-group. We sought to provide a thorough quantitative assessment of these 2 models.

Method

We performed a systematic literature review and captured information on discrimination, as quantified by the area under the receiver operator curve(AUC), and calibration, as quantified by the ratio of observed-to-expected mortality(O:E). We performed random effects meta-analysis of the performance of the individual models as well as pairwise comparisons and sub-group analysis by procedure type, time and continent.

Results

The ES2(AUC 0.783[95%CI 0.765-0.800];O:E 1.102[95%CI 0.943-1.289]) and STS(AUC 0.757[95%CI 0.727-0.785];O:E 1.111[95%CI 0.853-1.447]) both showed good overall discrimination and calibration. There was no significant difference in the discrimination of the two models(Difference in AUC -0.016; 95%CI -0.034 to -0.002;p0.09). However, the calibration of ES2 showed significant geographical variations(p < 0.001) and a trend towards miscalibration with time(p0.0057). This was not seen with STS.

Conclusions

ES2 and STS are both reliable predictors of short-term mortality following adult cardiac surgery in the populations from which they were derived. STS may have broader applications when comparing outcomes across continents and time periods as compared to ES2.

Outcomes after coronary artery bypass graft surgery: systematic review and meta-analysis comparing bilateral versus single internal thoracic artery grafts

Background

Patients with diabetes and/or obesity are at higher risk of adverse outcomes following coronary artery bypass grafting (CABG). The use of bilateral internal thoracic arteries (BITA) can potentially offer survival benefit in higher risk patients compared to single internal thoracic artery (SITA) in patients undergoing CABG, but the overall evidence base for BITA has not influenced guidelines, and there are concerns over increased risk of sternal wound complications.

Methods

We conducted a systematic review of the literature to identify observational studies and randomised controlled trials (RCT) comparing the efficacy (mortality) and safety (sternal wound infection) of BITA and SITA in diabetic and obese patients.

Results

We identified 18 observational studies and one RCT to obtain data comparing BITA and SITA in 19,589 diabetic patients, and two observational studies and one RCT comparing BITA and SITA in 6972 obese patients. Pooled analysis demonstrated significant mortality benefit of BITA compared to SITA in diabetic patients (risk ratio [RR] 0.79; 95% confidence interval [CI] 0.70, 0.90; Z=3.62, p=0.0003; I2=88%) (Figure 1a). Pooled analysis in obese patients found no significant difference in mortality rates between BITA and SITA (RR 0.73, 95% CI 0.47, 1.12; Z=1.43, p=0.15; I2=78%) (Figure 1b). A significantly higher rate of sternal wound complications following BITA was observed in diabetic (RR 1.53, 95% CI 1.23, 1.90; Z=3.86, p=0.0001; I2=4%) and obese patients (RR 2.24, 95% CI 1.63, 3.07; Z=5.00, p<0.00001; I2=0%).

Conclusions

BITA is associated with better long-term survival in diabetic patients, but most of the supportive data comes from observational studies. The effects of BITA grafting in patients who are obese is uncertain due to low numbers. BITA is associated with higher rates of sternal wound complications than SITA in both diabetic and obese patients. Further research is needed to understand if BITA has a role in higher risk patients undergoing CABG.

Figure 1. Pooled all-cause mortality

Funding Acknowledgement

Type of funding source: None

Improved long-term survival with coronary artery bypass graft surgery compared to percutaneous coronary intervention in diabetics with multivessel disease

Background

While randomized clinical trials have demonstrated the superiority of coronary artery bypass grafting (CABG) over percutaneous coronary intervention (PCI) in patients with diabetes and multivessel coronary artery disease (CAD), there remains a paucity of observational evidence comparing these two modalities.

Methods

Clinical and administrative databases for Canada's most populous province, Ontario, were linked to obtain records of all patients with angiographic evidence of multivessel CAD (defined as: 2-vessel and 3-vessel disease) treated with either isolated CABG or PCI from October 2008 to March 2017. Left main disease was excluded in the primary analysis. Baseline characteristics of patients undergoing CABG and PCI were compared and 1:1 propensity score matching was performed to account for baseline differences. 30-day mortality was compared in the matched groups. Late mortality and the composite of major cardiovascular and cerebrovascular events (MACCE, consisting of stroke, myocardial infarction (MI), repeat revascularization, and death) were compared between the matched groups using a stratified log rank test and Cox-proportional hazards model. The individual non-fatal components of MACCE were compared using the Fine-Gray model that accounted for death as a competing risk. A secondary analysis that included patients with left main disease was also performed for the outcome of late mortality. A sensitivity analysis that excluded patients with acute coronary syndrome was also conducted for late mortality.

Results

A total of 9,395 and 4,016 patients underwent CABG and PCI respectively. Prior to matching, CABG patients were younger (65.7 vs 68.5 years, p<0.001), more likely male (78% vs 73%, p<0.001) and with more severe CAD. Propensity score matching based on 24 baseline covariates yielded 3,782 well-balanced pairs. There was no difference in early mortality between CABG and PCI (2.3% vs 2.5%, p=0.65). The rate of all-cause mortality over 8-years was significantly higher with PCI compared to CABG (Figure- HR: 1.35, 95% CI: 1.23–1.50). The cumulative incidence of MI (HR 1.91, 95% CI: 1.66–2.20) and need for repeat revascularization (HR: 4.06, 95% CI: 3.54–4.66) were significantly higher with PCI over 8 years. There was no difference in late stroke between PCI and CABG (stroke (HR: 0.85, 95% CI: 0.68–1.07). Overall MACCE was higher in PCI compared to CABG (HR: 1.94, 95% CI: 1.80–2.09). In our secondary analysis that included patients with left main disease, findings were robust and late mortality remained higher with PCI compared to CABG (HR: 1.42, 95% CI: 1.30–1.54). In a sensitivity analysis where patients with acute coronary syndrome at the time of presentation were excluded, late mortality remained higher with PCI (HR: 1.30, 95% CI: 1.12–1.49) in 2,028 matched pairs.

Conclusions

In patients with multivessel CAD and diabetes we observed improved long-term mortality and freedom from MACCE at 8-years with CABG compared to PCI.

Figure 1

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Canadian Institutes of Health Research

Percutaneous vs. surgical revascularization for patients with unprotected left main stenosis: a meta-analysis of 5 years follow-up RCTs

Introduction

5-year survival of patients with ULM (Unprotected Left Main) stenosis according to the choice of revascularization (percutaneous vs. surgical) remains to be defined.

Methods and results

Randomized Controlled Trials (RTCs) comparing Percutaneous Coronary Intervention (PCI) vs. Coronary Artery Bypass Graft (CABG) with a follow-up of at least 5 years were included. All-cause death was the primary endpoint. MACCE (a composite endpoint of all-cause mortality, myocardial infarction [MI], stroke and repeat revascularization) along with its single components and cardiovascular (CV) death were the secondary ones. Analyses were stratified according to use of first vs. last generation coronary stents. Subgroup comparisons were performed according to Syntax Score (below or above 33) and to age (using cutoffs of each trial's subgroup analysis). 4 RCTs with 4394 patients were identified: 2197 were treated with CABG, 657 with first generation and 1540 with last generation stents. At 5 years rates of all-cause death did not differ (OR 0.93: 0.71–1.21), as those of CV death and stroke. CABG reduced rates of MACCE (OR 0.69: 0.60–0.79), mainly driven by MI (OR 0.48: 0.36–0.65) and revascularization (OR 0.53: 0.45–0.64). Benefit of CABG for MACCE was consistent, although with different extent, across values of Syntax Score (OR 0.76: 0.59–0.97 for values <32 and OR 0.63: 0.47–0.84 for values ≥33) while was not evident for “younger” patients (OR 0.83: 0.65–1.07 vs. OR 0.65: 0.51–0.84 for “older” patients, all CI 95%).

Conclusion

For patients with ULM disease, PCI and CABG yielded same survival benefit at 5 years. CABG reduced risk of MI, revascularization and MACCE especially in older patients and in those with diffuse coronary disease.

Funding Acknowledgement

Type of funding source: None

Effects of diabetes and obesity in patients undergoing coronary artery bypass graft surgery: ten-year results from the Arterial Revascularisation Trial

Background

Coronary artery bypass graft (CABG) surgery is an effective way to manage advanced coronary heart disease. Diabetes is associated with higher risk of mortality in patients undergoing CABG but the effects of obesity, and the interactions between diabetes and obesity in the context of CABG, have not been fully explored.

Methods

The Arterial Revascularisation Trial (ART) compared ten-year mortality in patients undergoing CABG randomised to single or bilateral internal thoracic arterial grafts. Effects of diabetes and obesity on mortality and risk (sternal wound complications) were explored. Diabetes was defined according to clinical history at baseline and combined insulin and non-insulin dependent patients, and obesity was defined as body mass index (BMI) ≥30kg/m2 at baseline.

Results

Information on diabetes, obesity and ten-year mortality were documented for 3094 patients who were included in the analysis. Mean age was 64 years, 86% male, mean weight 82kg and BMI 28. Diabetes was documented in 24% and obesity in 30% and as expected obese patients were more likely to be diabetic. The hazard ratios (95% confidence intervals) for ten-year mortality using the no diabetes, non-obese group as a reference were 1.33 (1.08, 1.64) (diabetes, non-obese), 0.93 (0.75, 1.16) (no diabetes, obese) and 1.18 (0.91, 1.54) (diabetes, obese) groups (Figure 1). Similar patterns of risk were observed whether patients were randomised to receive single or bilateral internal thoracic arteries and diabetes appeared to be the main driver of elevated risk of early sternal wound complications following CABG.

Conclusions

Obesity and diabetes are closely associated but our analysis shows that patterns of risk of death after CABG are not additive for these characteristics, and obesity may actually be associated with lower death rates in patients with and without diabetes. These findings will be explored further to understand mechanisms and interactions with other factors.

Figure 1. Hazard ratios at 10 years

Funding Acknowledgement

Type of funding source: None

Impaired coronary and myocardial flow in severe aortic stenosis is associated with increased apoptosis: a transthoracic Doppler and myocardial contrast echocardiography study

OBJECTIVE

To test the hypothesis that impaired coronary and myocardial blood flow are linked with increased myocyte apoptosis, thus establishing a link between pressure overload and left ventricular (LV) remodelling.

METHODS AND RESULTS

Peak diastolic coronary blood flow velocity (CBFV) was evaluated at transthoracic Doppler echocardiography, and signal intensity (SI) and the rate of SI rise (beta) were measured at myocardial contrast echocardiography in 11 patients with severe aortic stenosis and LV hypertrophy. In the same patients, biopsies were obtained from the anterolateral LV free wall during surgery and analysed for cardiomyocyte apoptosis. LV mass corrected CBFV (CBFVI) was significantly lower in patients than in controls (median 0.100 cm.g/s (interquartile range 0.07-0.115) v 0.130 cm.g/s (0.130-0.160), p = 0.002). Similarly, SI*beta was significantly lower in patients than in controls (11 1/s (8-66) v 83 1/s (73-95), p = 0.001). Apoptotic rate was increased in aortic stenosis more than 100-fold versus controls (1.2% (0.8-1.4) v 0.01% (0.01-0.01), p < 0.001) and inversely correlated with lower CBFVI and SI*beta (r = -0.77, p = 0.001 for both).

CONCLUSIONS

Patients with severe aortic stenosis and LV hypertrophy have impaired myocardial perfusion, which is associated with enhanced cardiomyocyte apoptosis. Impaired myocardial perfusion and the ensuing oxygen demand-supply imbalance may, at least partially, be responsible for increased apoptosis and possible transition to heart failure, thus establishing a link between pressure overload, LV remodelling, and heart failure.

Clinical and angiographic effects of chronic calcium channel blocker therapy continued beyond first postoperative year in patients with radial artery grafts: results of a prospective randomized investigation

BACKGROUND

This study was conceived to elucidate the clinical and angiographic effects of chronic calcium channel blocker therapy (CCCBT) continued after the first postoperative year in patients in whom the radial artery (RA) was used for myocardial revascularization.

METHODS AND RESULTS

Patients who received RA grafts at our institution and who at 1 year had no scintigraphic evidence of ischemia in the RA territory or angiographic evidence of RA malfunction (n=120) were randomly assigned to continue (n=63) or suspend (n=57) the CCCBT with diltiazem (120 mg/d). After 5 years, all patients were reassessed clinically and by stress myocardial scintigraphy, and 87 of them (45 from the continued group that continued CCCBT and 42 from the group that suspended CCCBT) were restudied angiographically. No differences regarding either the clinical and scintigraphic results or the RA angiographic status were demonstrated between the 2 groups.

CONCLUSIONS

After the first postoperative year, the continuation of CCCBT does not affect RA graft patency or clinical and scintigraphic results.

An unusual source of massive intra-abdominal hemorrhage during cardio-pulmonary bypass

Intra-abdominal hemorrhage occurring while on cardio-pulmonary bypass (CPB) is a rare and potentially lethal event during coronary artery bypass procedures. We herein report an unusual case in which massive intra-abdominal bleeding during CPB originated from a previously undiagnosed ovarian tumor, leading to acute anemization and hemodynamic instability and requiring emergency gynecologic surgery.

Should severe monolateral asymptomatic carotid artery stenosis be treated at the time of coronary artery bypass operation?

OBJECTIVE

The optimal treatment of severe monolateral asymptomatic carotid artery stenosis (SMACS) in patients undergoing coronary artery bypass grafting (CABG) is still controversial.

MATERIALS AND METHODS

This study is based on the in-hospital and mid-term (>5 years) clinical results of a cohort of 139 consecutive CABG patients with SMACS operated at our Institution between January 1989 and December 1995. In the first 73 patients (no carotid surgery group), the SMACS was left untouched at the time of coronary surgery, whereas in the remaining 66 (carotid endoarterectomy group), the carotid stenosis was treated either immediately before or concomitantly with the CABG procedure (depending on the severity of the anginal symptoms).

RESULTS

The overall preoperative characteristics of the patients were comparable. The in-hospital results were similar between the two groups with regard to mortality, stroke and major postoperative complications. However, at mid-term follow-up, significantly more patients of the no carotid surgery group suffered cerebral events (transient or permanent) ipsilateral to the SMACS or the lesion had to be operated on.

CONCLUSIONS

The concomitant treatment (either staged or simultaneous) of SMACS at the time of CABG does not influence the in-hospital results, but confers significant neurological protection during the years after the operation.

The unclampable ascending aorta in coronary artery bypass patients: A surgical challenge of increasing frequency

BACKGROUND

The unclampable ascending aorta (UAA) is a condition increasingly encountered during CABG procedures. We report our experience with CABG patients with UAA and place particular emphasis on the preoperative diagnosis and surgical management.

METHODS AND RESULTS

UAA was diagnosed in 211 of 4812 consecutive CABG patients (4.3%). On the basis of the chest radiograph, echocardiogram, and coronary angiograph, a preoperative diagnosis was achieved in only 58 patients (27.4%). An age of >70 years, diabetes, smoking, unstable angina, diffuse coronaropathy, and peripheral vasculopathy were all predictors of UAA. Patients were treated with hypothermic ventricular fibrillation (no-touch technique n=129) or beating heart revascularization (no-pump technique n=82) depending on the possibility of founding an arterial cannulation site. The overall in-hospital mortality rate was 2.8% (6 of 211) with no differences between the 2 surgical strategies. The no-touch technique was associated with a greater incidence of neurological complications (stroke and transient ischemic attack), renal insufficiency, and stay in the intensive care unit and hospital. However, at midterm follow-up, more patients of the no-pump group had ischemia recurrence.

CONCLUSIONS

A preoperative diagnosis of UAA is achievable only in a minority of patients, which highlights the necessity revising the current diagnostic protocols. The use of the no-touch technique is associated with an high perioperative risk but a superior possibility of complete revascularization, whereas adoption of the no-pump strategy ensures a smoother postoperative course at the expense of an higher incidence of ischemia recurrence.

Midterm endothelial function and remodeling of radial artery grafts anastomosed to the aorta

BACKGROUND

The purpose of this study was to elucidate the midterm endothelium-dependent vasodilatory capacity of radial artery grafts anastomosed to the aorta, as well as their morphometric evolution with the time.

METHODS

Five years after surgery we evaluated the response of aorta-anastomosed radial artery grafts to the endovascular infusion of acetylcholine in 11 of the first 61 patients operated on at our institution, and we compared it to the response with that of internal thoracic artery grafts. Moreover, the first 20 patients who had a perfect radial artery graft on angiography at 1 year were restudied at 5 years and subjected to a comparative analysis of the diameters of the radial artery graft and the grafted coronary arteries.

RESULTS

At midterm angiography, dilation of the 2 types of grafts was similar in response to acetylcholine administration (radial artery, from 2.61 +/- 0.39 to 2. 90 +/- 0.34 mm; internal thoracic artery, from 2.68 +/- 0.21 to 2.93 +/- 0.27 mm; P =.01 for both). The diameters of aorta-anastomosed radial artery grafts and grafted coronary arteries increased between both 1 and 5 years according to angiographic studies (radial artery grafts, from 2.08 +/- 0.45 to 2.54 +/- 0.53 mm; grafted coronary arteries, from 1.92 +/- 0.47 to 2.18 +/- 0.41 mm; P <.001 for both), but the increase was greater for the radial artery grafts (P <.001).

CONCLUSIONS

Aorta-anastomosed radial artery grafts maintain an appreciable capacity for endothelium-dependent vasodilatation 5 years after implantation and undergo a progressive increase in luminal diameter with time. These observations contradict the presumed tendency for progressive fibrous intimal hyperplasia to develop in radial artery grafts.

Are pulmonary homografts which were subjected to pulmonary hypertension more appropriate for aortic valve replacement than normal pulmonary homografts? A long-term multicentric echography study

OBJECTIVE

To compare long-term results of the European Homograft Bank (LHB) cryopreserved pulmonary homograft in left ventricular outflow tract (LVOT) subjected to pulmonary hypertension with those subjected to normal pulmonary pressure. The mid-term study of this material published in 1997 showed different results.

METHODS

Statistical analysis is calculated by the Kaplan-Meier survival curves, while differences in prevalence by the Log-Rank test.

RESULTS

Follow-up (FU) was available in 69 cases (76.7%): 46 in group 1 and 23 in group 2. Five patients have been excluded from the study because of early homograft explantation (technical problems or early valve incompetence). Fourteen out of 43 cases of group 1 (32. 6%) and seven out of 21 cases of group 2 (33.3%) have been explanted after 2.5-88 months and 7-88 months, respectively. Significant echography changes have been found in 19 of 43 (44.18%) of group 1 and 11 of 21 cases (52.38%) of group 2 during the follow-up. Histology showed essentially wear and tear induced lesions. Mean FU was 36.9 (range, 6-88) and 41.3 months (range, 4-88) for group 1 and 2, respectively. No significant difference in the long-term outcome have been found between the two groups (P=0.38).

CONCLUSION

Contrary to our previous echocardiography study of mid-term implants the long-term follow up of the PHGs implanted in the LVOT did not show better function of the pulmonary homografts subjected to pulmonary hypertension than those with normal pulmonary pressure. The high failure rate of the PHGs should discourage their use for LVOT reconstruction. Further echocardiography studies of remaining PHGs implanted in the LVOT, and gross and microscopic explant studies are required to judge on the definitive outcome of these grafts.

Hemodynamic and functional consequences of radial artery removal for coronary artery bypass grafting

Five years after surgery the echo-Doppler characteristics of the forearm circulation and the transcutaneous oxygen and carbon dioxide pressures of the operated and control arm were determined at rest and under conditions of hand exercise in 34 patients who received a radial artery graft for myocardial revascularization. Doppler measurements showed the ulnar compensation to radial artery removal, and transcutaneous measurements demonstrated a moderate degree of exercise-induced hand ischemia on the operated site.

Effect of skeletonization of the internal thoracic artery on vessel wall integrity

BACKGROUND

This study was conceived to evaluate the effect of internal thoracic artery (ITA) skeletonization on vessel wall integrity.

METHODS

Forty consecutive patients undergoing coronary artery bypass were randomized to receive a skeletonized (n = 22) or a pedicled (n = 18) ITA graft. ITA harvesting was performed by 2 experienced surgeons using the same instrumentation and technique. Specimens were examined by light and electron microscope in order to assess vascular wall integrity. A specific immunohistochemical staining and a computerized method were used to quantify the degree of endothelial integrity after surgical preparation.

RESULTS

Morphologic analysis revealed 2 cases of limited subadventitial hemorrhage (one for each group) and no case of major arterial damage. Immunohistochemical staining demonstrated an extremely high degree of maintenance of the endothelial integrity in both groups (97.2% +/- 1.9% in the skeletonized and 96.8% +/- 2.1% in the pedicled one; p = 0.53).

CONCLUSIONS

Skeletonization does not affect ITA wall integrity in humans submitted to coronary artery bypass procedures.

Superior extension of intraoperative brain damage in case of normothermic systemic perfusion during coronary artery bypass operations

OBJECTIVE

Despite the controversies on the potential detrimental effects of normothermic cardiopulmonary bypass on neurologic outcome, to date no correlation between the severity of intraoperative brain lesions and the cardiopulmonary bypass temperature used at operation has been reported. This study compares the prevalence and the severity of brain lesions in patients who underwent operation in condition of normothermic versus hypothermic systemic perfusion.

METHODS

Data are derived from the analysis of 2987 consecutive primary isolated myocardial revascularizations performed at our institution between April 1990 and January 1997. Of these cases, 1385 procedures were hypothermic and 1602 procedures were normothermic systemic perfusion. In all cases the neurologic outcome and extent of ischemic areas were prospectively recorded.

RESULTS

Overall, 31 patients had a perioperative stroke (1.0%). The prevalence of neurologic events was similar in the 2 groups (15 cases in the hypothermic group and 16 cases in the normothermic perfusion group; P, not significant). However, the mean Glasgow Outcome Scale score and computed tomography-demonstrated extent of brain lesions were significantly worse in the normothermic group.

CONCLUSIONS

Although the prevalence of intraoperative stroke was similar with hypothermic or normothermic cardiopulmonary bypass, the use of normothermic systemic perfusion was associated with more extended brain damage at computed tomographic scan and with a worse neurologic outcome. These results demand caution in the use of normothermic cardiopulmonary bypass and claim further investigation on the neurologic safety of normothermia.

Internal mammary artery grafts and competitive flow. Controversies persist

We report one case in which chronic native competitive flow from an almost normal target coronary artery did not influence IMA graft patency. This patient underwent control postoperative angiography 11 months after surgery and the mammary artery-left anterior descending graft was found to be normofunctioning despite the fact that the coronary artery showed no residual stenosis.

Patent side branches do not affect coronary blood flow in internal thoracic artery-left anterior descending anastomosis: an experimental study

BACKGROUND

It has been reported that large side branches of internal thoracic artery grafts may steal flow from the coronary circulation. Material an.

METHODS

To assess the importance of the side branches, we measured the proximal and distal flow and pressures (mean subclavian artery pressure and mean arterial anastomotic pressure) at baseline and during infusion of adenosine (0.5 mg/kg/min) in 10 Landrace pigs in which an internal thoracic artery-left anterior descending anastomosis was constructed without interruption of the side branches. The difference between proximal and distal flow was considered to represent the blood flow of the internal thoracic artery side branches. Measurements were then repeated after surgical occlusion of all the side branches.

RESULTS

At baseline, blood flow of the side branches represented 18% of the total flow in the proximal internal thoracic artery, and this percentage remained constant under the infusion of adenosine, which caused a 220% increase of the cardiac index and a 368% increase of the proximal flow. The infusion reduced the gradient along the left internal thoracic artery (mean subclavian artery pressure-mean arterial anastomotic pressure) from 15 to 10 mm Hg (P =.02) as the result of a lower mean subclavian artery pressure, although the mean arterial anastomotic pressure remained constant. Interruption of all the side branches resulted in a small and not significant increase in distal flow even after adenosine infusion.

CONCLUSION

These observations suggest that blood flow in the side branches is minimal either at baseline and under combined systemic and coronary vasodilation. Clinically significant flow steal from the coronary circulation to the internal thoracic artery side branches seems then unlikely.

Repair of an ascending aorta pseudoaneurysm by way of superior ministernotomy

A wide ascending aorta pseudoaneurysm occurring 10 years after uncomplicated aortic valve replacement was successfully repaired using a superior ministernotomy and femoral-femoral cannulation. In this setting, a limited sternal incision minimized the risk of pseudoaneurysm rupture during dissection and allowed safe isolation of the target cardiac structures.

Individualized surgical strategy for the reduction of stroke risk in patients undergoing coronary artery bypass grafting

BACKGROUND

This study was designed to evaluate the efficacy of a protocol of systematic screening of the ascending aorta and internal carotid arteries and individualization of the surgical strategy to the ascending aorta and internal carotid arteries status in reducing the stroke incidence among patients undergoing coronary artery bypass grafting.

METHODS

On the basis of a pre- and intraoperative screening of the ascending aorta and internal carotid arteries, 2,326 consecutive patients undergoing coronary artery bypass grafting were divided in low, moderate, and high neurologic risk groups. In the high-risk group dedicated surgical techniques were always adopted and the reduction of the neurologic risk was considered more important than the achievement of total revascularization.

RESULTS

The incidence of perioperative stroke in the high-risk group was similar to those of the other two groups (1.1 versus 1.3 and 1.1%, respectively; p = not significant); however, angina recurrence was significantly more frequent in the high-risk group.

CONCLUSIONS

The described strategy allows a low rate of perioperative stroke in high-risk patients undergoing coronary artery bypass grafting. Whether the reduction of the neurologic risk outweighs the benefits of complete revascularization remains to be determined.

Perioperative management of a patient with Werlhof disease undergoing myocardial revascularization

We herein report the case of a patient with idiopathic thrombocytopenic purpura (Werlhof disease) and coronary artery disease undergoing myocardial revascularization. The use of monomeric immunoglobulins, corticosteroids, platelets transfusion, use of a cell saver, normothermic cardiopulmonary bypass, aprotinine and homologous blood transfusion were combined in order to minimize the risk of bleeding complications in the postoperative period.

[Remodelling of the radial artery graft 5 years after aortocoronary bypass intervention]

BACKGROUND

The radial artery (RA) is being employed as coronary artery bypass graft with good results, but when it is proximally anastomosed to the ascending aorta, undergoes substantial hemodynamic changes which could lead to significant graft intimal hyperplasia. The aim of this study was to investigate the evolution of RA graft morphology over time.

METHODS

We studied 20 patients with a perfectly patent RA graft at both 1 and 5 year angiography after coronary artery bypass graft.

RESULTS

Both RA graft and grafted coronary artery diameters, assessed by quantitative coronary angiography, significantly increased at 5 years, in comparison to 1 year angiography (2.08 +/- 0.45 vs 2.54 +/- 0.53 mm, +22%, p < 0.001 and 1.92 +/- 0.47 vs 2.18 +/- 0.41 mm, +13.3%, p < 0.001, respectively).

CONCLUSIONS

Hemodynamic changes following RA employment for coronary artery bypass graft stimulate a remodeling of RA graft itself and of the grafted coronary arteries. The progressive increase of diameters observed in RA grafts strongly argues against the development of flow-limiting graft intimal hyperplasia when RA is proximally anastomosed to the ascending aorta. Moreover, grafted coronary artery dilation suggests that hemorrheologic changes following coronary artery bypass graft could play a major role in the development of RA remodeling over time.

Do internal mammary artery side-branches have the potential for haemodynamically significant flow steal?

OBJECTIVE

To evaluate the potential for flow steal of the internal mammary artery (IMA) side-branches at rest and in case of dilatation of their vascular bed (as probably occurs during physical exercise).

METHODS

Transthoracic echo-Doppler evaluation of IMA flow was performed preoperatively in 40 patients undergoing myocardial revascularization. IMA flow was measured at rest and in condition of peripheral vasodilatation (obtained using forced ventilation for 2 min, dypiridamole 0.84 mg/kg endovenous (e.v.), xantinole nicotinate 500 mg e.v., nifedipine 20 mg sublingual (s.l.)).

RESULTS

IMA mean peak systolic velocity increased 23% after forced ventilation (from 67 to 83 cm/s), 6% after dypiridamole (from 75 to 80 cm/s), 30% after xantinole infusion (from 62 to 81 cm/s) and 23% after nifedipine administration (from 60 to 74 cm/s). IMA flow increased 17.7% after forced ventilation (from 39.5 to 46.5 ml/min), 4.8% after dypiridamole (from 39.2 to 41.1 ml/min), 20.2% after xantinole infusion (from 41.4 to 49.8 ml/min) and 16.5% after nifedipine administration (from 41.6 to 48.5 ml/min).

CONCLUSIONS

The limited functional flow reserve of the in situ IMA, even after pure muscular vasodilatation, seems to minimize the possibility of significant flow steal from patent IMA graft collaterals.

[The radial artery in coronary surgery: the midterm clinical and angiographic results and the variation in vasoreactivity over time]

OBJECTIVE

To evaluate the mid-term angiographic results of radial artery grafts used for myocardial revascularization.

METHODS

The first 68 consecutive surviving patients who received a radial artery graft proximally anastomosed to the aorta at our institution were restudied in a five-year follow-up (mean 59 +/- 6.5 months); 48 of these patients had already undergone an early angiographic examination. The response of the radial artery to the endovascular infusion of serotonin was evaluated one and five years after surgery and the mid-term status of the radial artery grafts was correlated with the degree of stenosis of the target vessel and with the Ca(++)-channel-blocker therapy.

RESULTS

The patency and perfect patency rates of the radial artery five years after the operation were 91.9 and 87.0% respectively. All radial artery grafts that were patent early after surgery remained patent at mid-term follow-up and in seven patients early parietal irregularities disappeared after five years. The early propensity to graft spasm after serotonin challenge decreased markedly at mid-term follow-up. The continued use of Ca(++)-antagonists after the first postoperative year did not affect the status of the radial artery graft, whereas the severity of target-vessel stenosis markedly influenced the angiographic results.

CONCLUSIONS

The mid-term angiographic results of RA grafts used for myocardial revascularization are excellent. A correct surgical indication is essential, whereas continued therapy with Ca(++)-antagonists after the first year does not influence the mid-term angiographic results.

Midterm clinical and angiographic results of radial artery grafts used for myocardial revascularization

OBJECTIVE

To evaluate the midterm angiographic results of the use of radial artery grafts for myocardial revascularization.

METHODS

The first 68 consecutive surviving patients who received a radial artery graft proximally anastomosed to the aorta at our institution were studied again at 5 years (mean 59 +/- 6.5 months) of follow-up; 48 of these patients had previously undergone an early angiographic examination. The response of the radial artery to the endovascular infusion of serotonin was evaluated 1 and 5 years after the operation, and the midterm status of the radial artery graft was correlated with the degree of preoperative stenosis of the target vessel and with calcium-channel blocker therapy.

RESULTS

The patency and perfect patency rates of the radial artery grafts 5 years after the operation were 91.9% and 87.0%, respectively. All radial artery grafts that were patent early after the operation remained patent at midterm follow-up, and early parietal irregularities in 7 patients were seen to have disappeared after 5 years. The early propensity toward graft spasm after serotonin challenge was markedly decreased at midterm follow-up. The continued use of calcium-channel antagonists after the first postoperative year did not influence the radial artery graft status, whereas the preoperative severity of the target-vessel stenosis markedly influenced the angiographic results.

CONCLUSIONS

The midterm angiographic results of radial artery grafts used for myocardial revascularization are excellent. The correct surgical indication is essential. Continued therapy with calcium-channel antagonists after the first year does not influence the midterm angiographic results.

Steal phenomenon from mammary side branches: when does it occur?

BACKGROUND

The hemodynamic significance of patent mammary graft side branches is still controversial. This study was designed to evaluate the potential for flow steal of patent mammary side branches in different hemodynamic conditions.

METHODS

Echo-Doppler measurement of mammary graft flow was performed at rest and after dipyridamole-induced coronary vasodilatation in 10 patients with angiographic demonstration of evident mammary graft side branches (study group) and in 10 matched control patients (control group). Concomitant thallium-201 myocardial scintigraphy was performed to assess the adequacy of mammary flow to the myocardial oxygen demand. Patients of the study group were also submitted to flow evaluation in condition of selective muscular or combined systemic and coronary relaxation.

RESULTS

No difference in mammary flow and adequacy to myocardial oxygen demand was detected between patients of the study and control groups both at rest and after dipyridamole infusion. In patients with patent side branches the systolic-to-diastolic flow ratio was maintained in case of combined coronary and peripheral vasodilatation, whereas selective muscular relaxation led to an increase in the systolic and a reduction in the diastolic flow.

CONCLUSIONS

Flow steal from patent mammary graft side branches is possible only in case of selective muscular vasodilatation. As this situation is unlikely to occur in the clinical setting, the potential for flow steal of mammary side branches in cardiac surgery patients seems to be minimal.

Tepid systemic perfusion and intermittent isothermic blood cardioplegia in coronary surgery

BACKGROUND

To evaluate the safety and effectiveness of tepid perfusion and isothermic blood cardioplegia in coronary surgery.

METHODS

We studied 200 patients undergoing myocardial revascularization: 100 procedures were performed with moderate systemic hypothermia (28 degrees C) and cold crystalloid cardioplegia (4 degrees C); the other 100 patients received tepid systemic perfusion (TP) (34 degrees C) and intermittent blood cardioplegia at the same temperature according to the minicardioplegia technique (Group 2). The two groups were comparable with regards to age, extent of disease, preoperative left ventricular function and extra-corporeal circulation (ECC) time.

RESULTS

In the tepid group we observed a higher incidence of spontaneous resumption of cardiac rhythm at cross-clamp removal compared to the hypothermic group (93% vs 34%; p<0.001). No difference was found in cardiac index at specified intervals, myocardial enzymes, inotrope requirements, arrhythmias, need for vasopressors and postoperative blood loss. Fluid balance at the end of ECC was significantly lower in the tepid group (343+/-635 ml vs 883+/-925 ml; p<0.001). Hospital mortality and morbidity were the same in the two groups.

CONCLUSIONS

Our data suggest that TP and isothermic blood cardioplegia represent a simple, safe and effective method of systemic and myocardial protection which may be an alternative to traditional hypothermia.

Non-invasive evaluation of mammary artery flow reserve and adequacy to increased myocardial oxygen demand

OBJECTIVE

To evaluate the flow reserve and adequacy to meet myocardial requests in stress conditions of mammary artery-left anterior descending (IMA-LAD) grafts using a non-invasive method.

METHODS

Patients (20) with angiographic evidence of normofunctioning left IMA-LAD grafts were submitted to dypiridamole Tl201 myocardial scintigraphy and concomitant transthoracic echo-doppler evaluation of the IMA flow at a mean interval of 32.5 months after surgery.

RESULTS

Under basal conditions, the mean peak and end flow velocities in systole were 0.39 and 0.06 m/s, respectively. In diastole, the mean peak and end flow velocities were 0.27 and 0.02 m/s and mean tele-diastolic flow velocity was 0.14 m/s, with a mean systolic/diastolic ratio of 1.51. After dypiridamole infusion, mean systolic velocities were 0.47 (peak) and 0.23 (end) m/s, respectively + 20 and + 283%, whereas mean diastolic velocities were 0.56 (peak) and 0.06 (end) m/s, +107 and +200%, respectively. Mean tele-diastolic flow velocity increased to 0.32 m/s (+128%) and the systolic-diastolic index changed to 0.85. In all cases no significant scintigraphic evidence of induced ischemia was demonstrated in the LAD region.

CONCLUSIONS

Transthoracic echo-doppler evaluation combined with Tl201 myocardial scintigraphy is a useful tool for the assessment of IMA flow reserve and adequacy to stress conditions. In the late postoperative period, the IMA shows the possibility of increasing the flow velocity, almost 2-fold; the increase in flow is prevalently diastolic and leads to a complete reversal of the physiological systolic/diastolic flow ratio. The flow reserve of IMA is always able to meet the augmented myocardial oxygen demand after dypiridamole infusion.

Systematic clinical and angiographic follow-up of patients undergoing minimally invasive coronary artery bypass

OBJECTIVE

We herein analyze the results of the systematic clinical and angiographic control performed in a series of 77 consecutive patients undergoing minimally invasive coronary artery bypass.

METHODS AND RESULTS

From January 1995 to June 1997, 77 patients underwent minimally invasive coronary artery bypass at our institution. There was one inhospital death, one noncardiac late death, and five patients had to be reoperated for graft malfunction. A total of 76 patients underwent postoperative angiographic follow-up. In 66 cases (86.8%) the thoracic artery graft, the target vessel, and the anastomosis were patent and functioning normally. In one case the graft was occluded. In the remaining nine cases the thoracic artery graft was patent but with major anomalies of either the anastomosis, the target vessel, or the course of the thoracic artery. Patients operated using especially designed instruments had angiographic results clearly superior to those of patients operated using conventional instrumentation (perfect patency rate 100% vs 81.8%). At a mean follow-up of 18 months, 98.5% of the surviving patients are asymptomatic with negative myocardial scintigraphy.

CONCLUSIONS

The perfect patency rate of minimally invasive revascularization performed without the use of dedicated instruments is unacceptably low. The use of specific devices is likely to result in a substantial improvement in the angiographic results.

Integrated approach for revascularization in multivessel coronary artery disease and porcelain aorta

We report two cases in which combined beating heart revascularization of the left anterior descending artery (LAD) and percutaneous angioplasty of the non-LAD target arteries were adopted after the intraoperative detection of porcelain aorta and impossibility to complete surgical revascularization. This type of strategy preserves the benefits of surgical LAD grafting and complete revascularization and results in a simple and low-risk technical procedure in an otherwise challenging setting.

Palliative coronary artery surgery in patients with severe noncardiac diseases

Eight patients with severe systemic pathologies and refractory angina unsuitable for angioplasty were submitted to palliative surgical revascularization without the use of cardiopulmonary bypass and limited to the culprit vessels. Complete relief from angina was achieved in all patients without postoperative mortality and morbidity.

Lesions of the target vessel during minimally invasive myocardial revascularization

BACKGROUND

Minimally invasive coronary artery bypass grafting has recently been introduced into cardiac surgery. In this report we discuss the incidence of surgically induced distal target vessel stenosis in patients who undergo the minimally invasive coronary artery bypass grafting procedure, which represents a major drawback of the procedure in our experience.

METHODS

Doppler evaluation of mammary artery flow was performed postoperatively in all 55 patients who underwent minimally invasive coronary artery bypass grafting at our institution. Angiography was performed in the first 35 consecutive patients for control purposes and in 2 patients who complained of angina recurrence.

RESULTS

In 32 of the first 35 consecutive patients, the anastomosis was found to be functioning normally and the distal left anterior descending artery was normal; in the remaining 3 patients we found mammary artery occlusion, anastomotic stenosis, and stenosis of the anastomosis and the distal left anterior descending artery in 1 patient each. A distal left anterior descending artery stenosis was found in the only 2 patients who underwent late angiography.

CONCLUSIONS

Surgically induced distal target vessel stenosis represents a major drawback of minimally invasive coronary artery bypass grafting in our experience. Further improvement in the means of achieving coronary artery occlusion, as well as in anticoagulant and antiplatelet therapy, is mandatory before minimally invasive coronary artery bypass grafting can be confidently accepted into clinical practice.

Unusual right coronary artery anomaly with major implication during cardiac operations

We report a case in which an unrevealed high origin of the right coronary artery (almost 4 cm above the left coronary sinus) led to major complications during a routine atrial septal defect closure. We stress that, in absence of preoperative coronary angiography, coronary artery anomalies should always be considered and minimal ascending aorta manipulation and antegrade/ retrograde myocardial protection should be recommended.