Association of coronary angiography with ST-elevation and no ST-elevation in patients with refractory ventricular fibrillation - A substudy of the DOuble SEquential External Defibrillation for Refractory Ventricular Fibrillation (DOSE-VF randomized control trial).

BACKGROUND: Refractory ventricular fibrillation or pulseless ventricular tachycardia (rVF/pVT) during out-of-hospital cardiac arrest (OHCA) is associated with poor survival. Double sequential defibrillation (DSED) and vector change (VC) improved survival for rVF/pVT in the DOSE-VF RCT. However, the role of angiography and percutaneous coronary intervention (angiography/PCI) during the trial is unknown. OBJECTIVES: To determine the incidence of ST-elevation (STE) and no ST-elevation (NO-STE) on post-arrest ECG and the use of angiography/PCI in patients with rVF/pVT during the DOSE-VF RCT. METHOD: Adults (≥18-years) with rVF/pVT OHCA randomized in the DOSE-VF RCT who survived to hospital admission were included. The primary analysis compared the proportion of angiography in STE and NO-STE. We performed regression modelling to examine association between STE, the interaction with defibrillation strategy, and survival to discharge controlling for known covariates. RESULTS: We included 151 patients, 74 (49%) with STE and 77 (51%) with NO-STE. The proportion of angiography was higher in the STE cohort than NO-STE (87.8% vs 44.2%, p < 0.001); similarly the proportion of PCI was also higher (75.7% vs 9.1%, p < 0.001). Survival to discharge was similar between STE and NO-STE (63.5% vs 51.9%, p = 0.15). Use of angiography/PCI did not differ between defibrillation strategies. Decreased age (OR 0.95, 95% CI 0.92-0.98; p = 0.001) and angiography (OR 9.33, 95% CI 3.60-26.94; p < 0.001) were predictors of survival; however, STE was not. CONCLUSION: We found high rates of angiography/PCI in patients with STE compared to NO-STE, however similar rates of survival. Angiography was an independent predictor of survival. Improved rates of survival employing DSED and VC were independent of angiography/PCI.

SUPERIOR SVG: no touch saphenous harvesting to improve patency following coronary bypass grafting (a multi-Centre randomized control trial, NCT01047449).

BACKGROUND: Single centre studies support No Touch (NT) saphenous vein graft (SVG) harvesting technique. The primary objective of the SUPERIOR SVG study was to determine whether NT versus conventional (CON) SVG harvesting was associated with improved SVG patency 1 year after coronary artery bypass grafting surgery (CABG). METHODS: Adults undergoing isolated CABG with at least 1 SVG were eligible. CT angiography was performed 1-year post CABG. Leg adverse events were assessed with a questionnaire. A systematic review was performed for published NT graft patency studies and results aggregated including the SUPERIOR study results. RESULTS: Two hundred and-fifty patients were randomized across 12-centres (NT 127 versus CON 123 patients). The primary outcome (study SVG occlusion or cardiovascular (CV) death) was not significantly different in NT versus CON (NT: 7/127 (5.5%), CON 13/123 (10.6%), p = 0.15). Similarly, the proportion of study SVGs with significant stenosis or total occlusion was not significantly different between groups (NT: 8/102 (7.8%), CON: 16/107 (15.0%), p = 0.11). Vein harvest site infection was more common in the NT patients 1 month postoperatively (23.3% vs 9.5%, p < 0.01). Including this study's results, in a meta-analysis, NT was associated with a significant reduction in SVG occlusion, Odds Ratio 0.49, 95% Confidence Interval 0.29-0.82, p = 0.007 in 3 randomized and 1 observational study at 1 year postoperatively. CONCLUSIONS: The NT technique was not associated with improved patency of SVGs at 1-year following CABG while early vein harvest infection was increased. The aggregated data is supportive of an important reduction of SVG occlusion at 1 year with NT harvesting. TRIAL REGISTRATION: NCT01047449 .

A Clinical Risk Scoring Tool to Predict Readmission After Cardiac Surgery: An Ontario Administrative and Clinical Population Database Study.

BACKGROUND: Reducing readmission after cardiac surgery remains a quality improvement priority yet most readmission risk models examine only coronary artery bypass grafting (CABG). Our objective was to develop a predictive risk score for readmission after discharge in cardiac surgery. METHODS: All adults > 18 years undergoing isolated CABG, isolated/multiple valve, or combined CABG/valve surgery from 2008 to 2016 in Ontario were eligible. Risk factors for 30-day readmission after discharge were obtained through linkages of the CorHealth Ontario Cardiac Registry to other administrative health databases. Hazard ratios (HR) for risk factors were calculated using Cox proportional hazards regression with 95% confidence intervals (95% CI). We developed a clinical risk scoring tool weighted by beta coefficients from the final model. Discrimination and calibration was performed using c-statistics and comparing the predicted with observed probabilities across deciles of predicted risk. RESULTS: A total of 63,336 patients underwent CABG and/or valve surgery from 2008 to 2016. The 30-day readmission rate was 11.5% overall. Patients who were readmitted were older with higher incidences of cardiac comorbidities compared with nonreadmitted patients. Significant risk factors for readmission from the final model were prolonged length of stay (HR: 1.45; 95% CI: 1.57, 1.86; P < 0.0001), isolated valve surgery (HR: 1.35; 95% CI: 1.26, 1.44; P < 0.0001), in-hospital complications of sepsis (HR: 1.47; 95% CI: 1.05, 2.07; P = 0.024), and acute myocardial infarction (HR: 1.36; 95% CI: 1.09, 1.71; P = 0.007). A clinical risk scoring tool with 22 variables was derived that delineated patients into 1 of 5 risk quintiles. The c-statistic for the overall model was 0.63. CONCLUSIONS: Readmission after cardiac surgery is common and moderately predictable in this contemporary cohort.

The radial artery is protective in women and men following coronary artery bypass grafting-a substudy of the radial artery patency study.

BACKGROUND: Studies have demonstrated that female sex is an adverse risk factor in CABG. The primary aim of this study was to determine whether the radial artery (RA) was associated with reduced angiographic occlusion compared to the saphenous vein graft (SVG) stratified by sex in the multi-centered Radial Artery Patency Study (NCT00187356). METHODS: Between 1996-2001, 529 patients less than 80 years, with graftable triple-vessel disease underwent isolated CABG across 11 centers with late angiographic and clinical follow-up. The primary objective was to compare complete occlusion of RA and SVG with respect to sex. The secondary objective was to determine cumulative patency of both grafts along with predictors of late graft occlusion stratified by sex. The additional objective was to compare major adverse cardiac events (MACE, defined as cardiac mortality, myocardial infarction or re-intervention) between women and men. RESULTS: Of the 529 enrolled patients (13.4% women), 269 (women: n=41, 15.2%) underwent late angiography at a mean of 7.7±1.5 years after CABG. Women were older (64.1±6.7 versus 59.1±8.0 years, P<0.01) with a higher rate of diabetes (43.9% versus 28.5%, P=0.05). Smoking history was less common (48.8% versus 75.4%, P<0.01) while the mean number of grafts per patient were similar (women: 3.8±0.7, men: 3.8±0.6, P=0.65). RA occlusions were lower than SVG in women (RA: 9.8%, SVG: 26.8%, P=0.05) and in men (RA: 8.8%, SVG: 17.1%, P=0.01). The rate of RA and SVG occlusion was not statistically different between women and men, and cumulative patency curves were also similar between sexes for the RA and study SVG. Multivariable modeling showed that having a RA (versus SVG) was protective in women [odds ratio (OR) 0.15, P=0.04] and men: (OR 0.49, P=0.02). MACE (P=0.15) and event-free cardiac survival (log-rank P=0.14) were similar between women and men. CONCLUSIONS: Radial arteries are protective in both women and men with comparable burden of coronary disease and revascularization.

Unmeasured Confounders in Observational Studies Comparing Bilateral Versus Single Internal Thoracic Artery for Coronary Artery Bypass Grafting: A Meta-Analysis.

BACKGROUND: Observational studies suggest a survival advantage with bilateral single internal thoracic artery (BITA) versus single internal thoracic artery grafting for coronary surgery, whereas this conclusion is not supported by randomized trials. We hypothesized that this inconsistency is attributed to unmeasured confounders intrinsic to observational studies. To test our hypothesis, we performed a meta-analysis of the observational literature comparing BITA and single internal thoracic artery, deriving incident rate ratio for mortality at end of follow-up and at 1 year. We postulated that BITA would not affect 1-year survival based on the natural history of coronary artery bypass occlusion, so that a difference between groups at 1 year could not be attributed to the intervention. METHODS AND RESULTS: We searched MEDLINE and Pubmed to identify all observational studies comparing the outcome of BITA versus single internal thoracic artery. One-year and long-term mortality for BITA and single internal thoracic artery were compared in the propensity-score-matched (PSM) series, that is, the form of observational evidence less prone to confounders. Thirty-eight observational studies (174 205 total patients) were selected for final comparison. In the 12 propensity-score-matched series (34 019 patients), the mortality reduction for BITA was similar at 1 year and at the end of follow-up (incident rate ratio, 0.70; 95% confidence interval, 0.60-0.82 versus 0.77; 95% confidence interval, 0.70-0.85; P for subgroup difference=0.43). CONCLUSIONS: Unmeasured confounders, rather than biological superiority, may explain the survival advantage of BITA in observational series.

Mechanisms, Consequences, and Prevention of Coronary Graft Failure.

Graft failure occurs in a sizeable proportion of coronary artery bypass conduits. We herein review relevant current evidence to give an overview of the incidence, pathophysiology, and clinical consequences of this multifactorial phenomenon. Thrombosis, endothelial dysfunction, vasospasm, and oxidative stress are different mechanisms associated with graft failure. Intrinsic morphological and functional features of the bypass conduits play a role in determining failure. Similarly, characteristics of the target coronary vessel, such as the severity of stenosis, the diameter, the extent of atherosclerotic burden, and previous endovascular interventions, are important determinants of graft outcome and must be taken into consideration at the time of surgery. Technical factors, such as the method used to harvest the conduits, the vasodilatory protocol, the storage solution, and the anastomotic technique, also play a major role in determining graft success. Furthermore, systemic atherosclerotic risk factors, such as age, sex, diabetes mellitus, hypertension, and dyslipidemia, have been variably associated with graft failure. The failure of a coronary graft is not always correlated with adverse clinical events, which vary according to the type, location, and reason for failed graft. Intraoperative flow verification and secondary prevention using antiplatelet and lipid-lowering agents can help reducing the incidence of graft failure.

Impact of South Asian Ethnicity on Long-Term Outcomes After Coronary Artery Bypass Grafting Surgery: A Large Population-Based Propensity Matched Study.

BACKGROUND: Ethnicity is an important predictor of coronary artery bypass graft surgery (CABG) outcomes. South Asians (SA), one of the largest ethnic groups with a high burden of cardiovascular disease, are hypothesized to have inferior outcomes after CABG compared to other ethnic groups. Given the paucity and controversy of literature in this area, the objective of this study was to examine the impact of SA versus the general population (GP) on long-term outcomes following CABG. METHOD AND RESULTS: Using administrative databases and a surname algorithm, 83 850 patients (SA: 2653, GP: 81 197) who underwent isolated CABG in Ontario, Canada from 1996 to 2007 were identified; mean follow-up was 9.1±3.9 years. SA were younger (SA: 61.7±9.4, GP: 64.1±10.0 years, standardized difference=0.25) with more cardiac risk factors, including diabetes (SA: 54.1%, GP: 34.9%, standardized difference =0.40). Propensity-score matching resulted in 2473 matched pairs between SA and GP with all baseline covariates being balanced (standardized difference <0.1). Being a SA compared to the GP was protective against freedom from major adverse cardiac and cerebrovascular events, defined by all-cause death, myocardial infarction, stroke, or coronary reintervention: Adjusted Cox-proportional hazard ratio 0.91, 95% CI (0.83-0.99), adjusted-P=0.04; this was also true for freedom from all-cause mortality: hazard ratio 0.81, 95% CI (0.72-0.91), adjusted P=0.0004. The adjusted proportion of major adverse cardiac and cerebrovascular events was lower in the SA (SA: 34.7%, GP: 37.8%, McNemar P=0.03), driven largely by all-cause mortality (SA: 20.4%, GA: 24.3%, McNemar P=0.001). CONCLUSIONS: Contrary to existing notions, our study finds that being a SA is protective with respect to freedom from long-term major adverse cardiac and cerebrovascular events and mortality after CABG. More studies are required to corroborate and explore causal factors of these findings.

Comparison of Radial Artery and Saphenous Vein Graft Stenosis More Than 5 Years After Coronary Artery Bypass Grafting.

BACKGROUND: Graft stenosis may be associated with future graft failure. The purpose of this investigation was to compare graft stenosis between radial artery (RA) grafts and saphenous vein grafts (SVGs) at least 5 years postoperatively using the multicenter Radial Artery Patency Study (RAPS) data. METHODS: Two hundred thirty-four patients underwent late invasive angiography after coronary artery bypass operations. The study population consists of 163 patients with thrombolysis in myocardial infarction (TIMI) 3 flow of both the RA graft and study SVGs. Angiograms were reviewed centrally and in a blinded fashion. Graft stenosis was recorded for the proximal anastomosis, graft body, and distal anastomosis; significant stenosis was defined as greater than or equal to 50%. Major adverse cardiac events (MACE) were reported in patients with and those without significant graft stenosis. RESULTS: There was no difference in significant graft stenosis of the patent RA grafts and SVGs (14 of 163 [8.6%] versus 19 of 163 [11.7%]) or in the proximal anastomosis (5 of 163 [3.1%] versus 5 of 163 [3.1%]), graft body (6 of 163 [3.7%] versus 13 of 163 [8.0%]), or distal anastomosis (4 of 163 [2.5%] versus 5 of 163 [3.1%]) considered separately. However, the overall burden of graft body disease was higher in SVGs (p = 0.03). MACE was higher in patients with significant graft stenosis than in patients without stenosis (10 of 28 [35.7%] versus 7 of 135 [5.2%]; p < 0.0001). CONCLUSIONS: There was no significant difference in the rates of significant stenosis of patent RA grafts and SVGs more than 5 years postoperatively. However, the burden of graft body stenosis was less in RA grafts compared with SVGs, suggesting that the RA grafts will continue to outperform the SVGs late after operation.

Long-term Follow-up of Coronary Artery Bypass Patients With Preoperative and New Postoperative Native Coronary Artery Chronic Total Occlusion.

BACKGROUND: Chronic total occlusions (CTOs) of native coronary arteries are a frequent finding among patients who are referred for surgical revascularization with coronary artery bypass grafting (CABG). The long-term clinical significance of native coronary artery CTO identified at baseline and 1 year after CABG is unknown. METHODS: All patients who underwent 1-year follow-up angiography as part of the multicentre Radial Artery Patency Study (RAPS) were assessed for late clinical events. RESULTS: At a mean follow-up of 7.3 ± 2.9 years, the study group of 388 patients had the following outcomes: 39 (10%) deaths, 6 (1.5%) cases of nonfatal myocardial infarction, and 19 (4.9%) cases of percutaneous coronary intervention (PCI). CTO of ≥ 1 native coronary artery in the baseline preoperative coronary angiogram was demonstrated in 240 (61.9%) patients. The composite of all-cause death, nonfatal myocardial infarction, and PCI occurred significantly more often in patients with at least 1 preoperative CTO than in patients without a preoperative CTO (20% vs 11%; P = 0.048). A new native coronary artery CTO 1 year after surgery occurred in 169 (43.6%) patients. The composite of all-cause death, nonfatal myocardial infarction, and PCI occurred significantly more often in patients with a new CTO 1 year after CABG compared with those without a new CTO (21.3% vs 12.8%; P = 0.028). CONCLUSIONS: In patients undergoing CABG, both preoperative CTOs and new CTOs that develop 1 year after surgery are associated with adverse long-term clinical outcomes.

A Review of Propensity-Score Methods and Their Use in Cardiovascular Research.

Observational studies using propensity-score methods have been increasing in the cardiovascular literature because randomized controlled trials are not always feasible or ethical. However, propensity-score methods can be confusing, and the general audience may not fully understand the importance of this technique. The objectives of this review are to describe (1) the fundamentals of propensity score methods, (2) the techniques to assess for propensity-score model adequacy, (3) the 4 major methods for using the propensity score (matching, stratification, covariate adjustment, and inverse probability of treatment weighting [IPTW]) using examples from previously published cardiovascular studies, and (4) the strengths and weaknesses of these 4 techniques. Our review suggests that matching or IPTW using the propensity score have shown to be most effective in reducing bias of the treatment effect.