Cellular and molecular approaches to enhance myocardial recovery after myocardial infarction

Reperfusion therapy has resulted in significant improvement in post-myocardial infarction morbidity and mortality in over the last 4 decades. Nonetheless, it is well recognized that simply restoring patency of the epicardial artery may not stop or reverse damage at microvascular level, and myocardial salvage is often suboptimal. Numerous efforts have been undertaken to elucidate the mechanisms underlying extensive myonecrosis to facilitate the discovery of therapies to provide additional and incremental benefits over current therapeutic pathways. To date, conclusively effective strategies to promote myocardial recovery have not yet been established. Novel approaches are investigating the foundational cellular and molecular bases of myocardial ischemia and irreversible injury. Herein, we review the emerging concepts and proposed therapies that may improve myocardial protection and reduce infarct size. We examine the preclinical and clinical evidence for reduced infarct size with these strategies, including anti-inflammatory agents, intracellular ion channel modulators, agents affecting the reperfusion injury salvage kinase (RISK) and nitric oxide signaling pathways, modulators of mitochondrial function, anti-apoptotic agents, and stem cell and gene therapy. We review the potential reasons of failures to date and the potential for new strategies to further promote myocardial recovery and improve prognosis.

Pre-operative use of aspirin in patients undergoing coronary artery bypass grafting: a systematic review and updated meta-analysis

Background

Aspirin therapy improves saphenous vein graft (SVG) patency in patients undergoing coronary artery bypass graft (CABG), however, its use in the pre-operative period remains controversial. Therefore, we conducted a systematic review and meta-analysis of randomized-controlled trials (RCTs) to update the evidence about risk and benefits of pre-operative aspirin therapy in patients undergoing CABG.

Methods

Electronic databases (Medline, Embase, PubMed, Cochrane Library, and Scopus) were searched to identify RCTs evaluating the effect of aspirin versus placebo/control before CABG. Two investigators independently and in duplicate screened citations and extracted data and rated the risk of bias. The strength of evidence was appraised using the Grading of Recommendation Assessment, Development, and Evaluation (GRADE) approach. Meta-analysis was performed using a random-effects model. The main outcomes of interest were 30-day mortality, peri-operative myocardial infarction (MI), chest tube drainage and SVG occlusion.

Results

A total of 13 RCTs involving 4,377 participants (2,266/2,111 pre-operative aspirin/control) met the inclusion criteria. Pre-operative aspirin reduced the risk of SVG occlusion [risk ratio (RR): 0.69, 95% confidence interval (CI): 0.49-0.97, P=0.03, I²=16%], but no differences in mortality (RR: 1.41, 95% Cl: 0.73-2.74, I²=0%) and MI (RR: 0.84, 95% CI: 0.69-1.03, I²=0%) were found. However, pre-operative aspirin increased chest tube drainage (MD: 100.40 mL, 95% CI: 24.32-176.47 mL, P=0.01, I²=84%) and surgical re-exploration (RR: 1.52, 95% CI: 1.02-2.27, P=0.04, I²=8%), with no significant difference in RBC transfusion (RR: 1.06, 95% CI: 0.90-1.25, I²=35%).

Conclusions

Based on trials where the rated body of evidence was of low to very-low quality, pre-operative aspirin improves SVG patency but increases chest tube drainage and need for surgical re-exploration.

Is Fractional Flow Reserve Useful in Assessing Coronary Artery Fistula: A Case-Based Discussion and Review

We present two cases where fractional flow reserve (FFR) was utilised to guide management of coronary artery fistula (CAF), an approach advocated in recent case studies. CAF is a coronary anomaly that may present with a variety of syndromes though is frequently asymptomatic. When to exclude the fistula (surgically or percutaneously) is not always clear. A way to quantify if the fistula is physiologically meaningful would be advantageous. Our findings suggest FFR may only be assessing the concomitant epicardial coronary artery disease (CAD) rather than the degree of coronary steal and its routine use in this setting is not supported.

Antithrombotic therapy in patients receiving saphenous vein coronary artery bypass grafts: a protocol for a systematic review and network meta-analysis

INTRODUCTION

The current evidence for the prevention of saphenous vein graft failure (SVGF) after coronary artery bypass graft (CABG) surgery consists of direct head-to-head comparison of treatments (including placebo) in randomised-controlled trials (RCTs) and observational studies. However, summarising the evidence using traditional pairwise meta-analyses does not allow the inclusion of data from treatments that have not been compared head to head. Exclusion of such comparisons could impact the precision of pooled estimates in a meta-analysis. Hence, to address the challenge of whether aspirin alone or in addition to another antithrombotic agent is a more effective regimen to improve SVG patency, a network meta-analysis (NMA) is necessary. The objectives of this study are to synthesise the available evidence on antithrombotic agents (or their combination) and estimate the treatment effects among direct and indirect treatment comparisons on SVGF and major adverse cardiovascular events, and to generate a treatment ranking according to their efficacy and safety outcomes.

METHODS

We will perform a systematic review of RCTs evaluating antithrombotic agents in patients undergoing CABG. A comprehensive English literature search will be conducted using electronic databases and grey literature resources to identify published and unpublished articles. Two individuals will independently and in duplicate screen potential studies, assess the eligibility of potential studies and extract data. Risk of bias and quality of evidence will also be evaluated independently and in duplicate. We will investigate the data to ensure its suitability for NMA, including adequacy of the outcome data and transitivity of treatment effects. We plan to estimate the pooled direct, indirect and the mixed effects for all antithrombotic agents using a NMA.

ETHICS AND DISSEMINATION

Due to the nature of the study, there are no ethical concerns nor informed consent required. We anticipate that this NMA will be the first to simultaneously assess the relative effects of multiple antithrombotic agents in patients undergoing CABG. The results of this NMA will inform clinicians, patients and guideline developers the best available evidence on comparative effects benefits of antithrombotic agents after CABG while considering the side effect profile to support future clinical decision-making. We will disseminate the results of our systematic review and NMA through a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42017065678.

Radial versus femoral approach for same-day inter-facility transfer for percutaneous coronary intervention

BACKGROUND

The use of radial approach for coronary angiography, followed by same-day inter-facility transfer for percutaneous coronary intervention (PCI) has not yet been evaluated.

OBJECTIVES

We sought to assess the safety and feasibility of using the transradial as compared to the transfemoral approach in patients undergoing diagnostic angiogram with same-day transfer to a PCI facility.

METHODS

Patients that underwent diagnostic coronary angiography between January 2011 and June 2017 in a referring facility, and were transferred for same-day PCI were included. Patients' demographics, as well as procedural data and in-hospital outcome, were collected.

RESULTS

Three hundred fifty-two participants were included. Of these, 36 (10.2%) patients received transradial access. Patients in the transradial group were older (68 ± 10 vs 62 ± 12 years, P = 0.007), and received a significantly higher total dose of heparin including both, diagnostic and PCI procedures (5935 ± 1865 vs 10029 ± 2771 units, P < 0.001). None of the transradial patients experienced bleeding or access-related complications. In the transfemoral group, 9 (3%) vascular-access complications were recorded. Contrast volume was lower for transradial patients (177 ± 47 vs 216 ± 75 mL, P < 0.001). A higher proportion of outpatients were discharged from the PCI-center the same day after transradial procedures (53% vs 1.3%, P < 0.001).

CONCLUSIONS

Transradial access for inter-facility transfer for PCI after diagnostic angiogram appears safe and feasible, without increasing the risk for ischemic hand complications. Transradial access was associated with fewer bleeding and vascular access-site complications, and with a higher likelihood for a same-day discharge home in outpatients.

Healing of Iatrogenic Coronary Dissection and Intramural Hematoma: Insights From OCT

A 57-year-old female presented with Canadian Cardiovascular Society class 2 angina and a positive stress test. Angiography was performed via right radial approach, resulting in spiral dissection and TIMI 0 flow.

Nitroglycerin-Derived Pd/Pa for the Assessment of Intermediate Coronary Lesions

OBJECTIVES

To assess the predictive value of Pd/Pa after nitroglycerin administration (Pd/Pa[N]) as compared with standard fractional flow reserve (FFR).

METHODS

Consecutive patients with intermediate coronary lesions assessed by FFR between January 2014 and October 2015 were included. We measured Pd/Pa at baseline, Pd/Pa(N), and Pd/Pa after incremental doses of intracoronary adenosine.

RESULTS

A total of 134 patients (27% females; mean age, 65 years) were included. The diagnostic performance of Pd/Pa(N) and identification of cut-off value for Pd/Pa(N) compared with FFR threshold of 0.8 using receiver-operating characteristic (ROC) area under the curve analysis was between 0.98 (95% confidence interval, 0.95-1.00; P<.05) for 48 μg and 0.86 (95% confidence interval, 0.79-0.94; P<.05) for 240 μg adenosine. Pd/Pa(N) ≤0.8 had 100% positive predictive value. Pd/Pa(N) ≥0.94 provided 100% negative predictive value with a high sensitivity (>92%). Optimal diagnostic accuracy of Pd/Pa(N) was achieved for values ≤0.84. The Pearson's correlation between Pd/Pa(N) and FFR varied between 0.89 for 24 μg adenosine and 0.77 for 240 μg (P<.01).

CONCLUSION

Pd/Pa(N) values can be used for diagnosis of hemodynamically significant lesions. Pd/Pa(N) correlates well with standard FFR. Pd/Pa(N) cut-off of ≤0.8 can be considered significant without need for adenosine injection. The value of using adenosine whenever Pd/Pa(N) is ≥0.94 is limited.

Effects of ticagrelor versus clopidogrel on platelet function in fibrinolytic-treated STEMI patients undergoing early PCI

OBJECTIVES

Patients undergoing PCI early after fibrinolytic therapy are at high risk for both thrombotic and bleeding complications. We sought to assess the pharmacodynamic effects of ticagrelor versus clopidogrel in the fibrinolytic-treated STEMI patients undergoing early PCI.

METHODS AND RESULTS

Patients undergoing PCI within 24 hours of tenecteplase (TNK), aspirin, and clopidogrel for STEMI were randomized to receive additional clopidogrel 300 mg followed by 75 mg daily or ticagrelor 180 mg followed by 90 mg twice daily. The platelet reactivity units (PRU) were measured with the VerifyNow Assay before study drug administration (baseline) at 4 and 24 hours post-PCI. The primary end point was PRU ≤208 at 4 hours. A total of 140 patients (74 in ticagrelor and 66 in clopidogrel group) were enrolled. The mean PRU values at baseline were similar for the 2 groups (257.8±52.9 vs 259.5±56.7, P=.85, respectively). Post-PCI, patients on ticagrelor, compared to those on clopidogrel, had significantly lower PRU at 4 hours (78.7±88 vs 193.6±86.5, respectively, P<.001) and at 24 hours (34.5±35.0 and 153.5±75.5, respectively, P<.001). The primary end point was observed in 87.8% (n=65) in the ticagrelor-treated patients compared to 57.6% (n=38) of clopidogrel-treated patients, P<.001.

CONCLUSION

Fibrinolysis-treated STEMI patients who received clopidogrel and aspirin at the time of fibrinolysis and were undergoing early PCI frequently had PRU >208. In this high-risk population, ticagrelor provides more prompt and potent platelet inhibition compared with clopidogrel (Funded by Astra Zeneca; NCT01930591, https://clinicaltrials.gov/ct2/show/NCT01930591).

Duration of dual antiplatelet therapy and associated outcomes following percutaneous coronary intervention for acute myocardial infarction: contemporary practice insights from the Canadian Observational Antiplatelet Study

Aims

There is a paucity of real-world, contemporary data of practice patterns and clinical outcomes following dual-antiplatelet therapy (DAPT) in acute myocardial infarction (AMI) patients treated with percutaneous coronary intervention (PCI).

Methods and results

The Canadian Observational Antiplatelet Study was a prospective, multicentre, cohort study examining adenosine diphosphate receptor antagonist use following PCI for AMI. We compared practice patterns, patient characteristics, and clinical outcomes in relation to DAPT duration (<6 weeks, 6 weeks to <6 months, 6 to <12, and ≥12 months). The primary outcome was the composite of non-fatal AMI, unplanned coronary revascularization, stent thrombosis, new or worsening heart failure, cardiogenic shock, or stroke. We identified 2034 patients with AMI treated with PCI. DAPT duration was <6 weeks in 5.2% of patients; 6 weeks to <6 months in 7.0%; 6 to <12 months in 12.6%; and ≥12 months in 75.3%. Patients who discontinued DAPT early had higher GRACE risk scores. Overall, mortality rate at 15 months was 2.5%. Compared with a duration of DAPT of ≥12 months, discontinuation of DAPT <6 weeks (P < 0.0001) and 6 weeks to <6 months (P = 0.02), but not 6 months to <12 months (P = 0.06), were independently associated with a higher incidence of the primary outcome among survivors.

Conclusion

One-in-four patients with AMI treated with PCI discontinued DAPT prior to the guideline-recommended 12-month duration. Patients in whom DAPT was discontinued early were at higher baseline risk and had higher rates of non-fatal ischaemic events during follow up.

Bare metal versus drug eluting stents for ST-segment elevation myocardial infarction in the TOTAL trial

BACKGROUND

The safety and efficacy of drug eluting stents (DES) in the setting of ST elevation myocardial infarction (STEMI) is not well established.

METHODS

In the TOTAL trial, patients presenting with STEMI were randomized to routine thrombectomy versus PCI alone. In this post-hoc analysis, propensity matching was used to assess relative safety and efficacy according to type of stent used.

RESULTS

Each propensity-matched cohort included 2313 patients. The composite primary outcome of cardiovascular death, recurrent MI, cardiogenic shock or class IV heart failure within one year was lower in the DES group (HR 0.67; 95% CI 0.54 to 0.84, p=0.0004). Cardiovascular death (HR 0.61; 95% CI 0.43 to 0.86, p=0.005), recurrent MI (HR 0.51; 95% CI 0.35 to 0.75, p=0.0005), target vessel revascularization (HR 0.47; 95% CI 0.36 to 0.62, p<0.0001) and stent thrombosis (HR 0.60; 95% CI 0.40 to 0.89, p=0.01) were lower in the DES group. There was no difference in major bleeding between groups.

CONCLUSIONS

In this observational analysis, the use of DES was associated with improvement in cardiovascular outcomes compared to the use of BMS. These results support the use of DES during primary PCI for STEMI.

Effects of hypertonic saline solution on body weight and serum creatinine in patients with acute decompensated heart failure

AIM

To test the safety and effectiveness of hypertonic saline solution (HSS + F) as a strategy for weight loss and prevention of further deterioration of renal function.

METHODS

Patients admitted with acute decompensated heart failure (ADHF) who received HSS + F were included in the study. After a period of a standard ADHF treatment, our patients received an intravenous infusion of furosemide (250 mg) combined with HSS (150 mL of 3% NaCl) twice a day for a mean duration of 2.3 d. Our primary outcomes were weight loss and a change in serum creatinine per day of treatment. The parameters of the period prior to treatment with HSS + F were compared with those of the period with HSS + F.

RESULTS

A total of 47 patients were included. The mean creatinine on admission was 155 μmol/L ± 65 μmol/L, the ejection fraction was 40% ± 17%. The experimental treatment (HSS + F) resulted in greater weight loss per day of treatment than the standard treatment (-1.4 kg/d ± 1.4 kg/d vs -0.4 kg/d ± 1.0 kg/d, P = 0.0168). Importantly, the change in creatinine was not significantly different.

CONCLUSION

This study supports the effectiveness of HSS + F on weight loss in patients with ADHF. The safety profile, particularly with regard to renal function, leads us to believe that HSS + F may be a valuable option for those patients presenting with ADHF who do not respond to conventional treatment with intravenous furosemide alone.

A review of strategies for infarct size reduction during acute myocardial infarction

Advances in medical and interventional therapy over the last few decades have revolutionized the treatment of acute myocardial infarction. Despite the ability to restore epicardial coronary artery patency promptly through percutaneous coronary intervention, tissue level damage may continue. The reported 30-day mortality after all acute coronary syndromes is 2 to 3%, and around 5% following myocardial infarction. Post-infarct complications such as heart failure continue to be a major contributor to cardiovascular morbidity and mortality. Inadequate microvascular reperfusion leads to worse clinical outcomes and potentially strategies to reduce infarct size during periods of ischemia-reperfusion can improve outcomes. Many strategies have been tested, but no single strategy alone has shown a consistent result or benefit in large scale randomised clinical trials. Herein, we review the historical efforts, current strategies, and potential novel concepts that may improve myocardial protection and reduce infarct size.

Randomized Trial of Compression Duration After Transradial Cardiac Catheterization and Intervention

BACKGROUND

Radial artery occlusion is a known complication following transradial cardiac catheterization. A shorter duration of postprocedural radial clamp time may reduce radial artery occlusion (RAO) but might be associated with incomplete hemostasis.

METHODS AND RESULTS

In total, 568 patients undergoing transradial diagnostic cardiac catheterization were randomly assigned to either 20 minutes (ultrashort) or 60 minutes (short) hemostatic compression time using patent hemostasis. Subsequently, clamp pressure was reduced gradually over 20 minutes. Access site hemostasis and RAO were assessed after clamp removal. Repeated assessment of RAO was determined at 1 week in 210 (37%) patients. Mean age was 64±11 years, and 30% were female. Percutaneous coronary intervention was performed in 161 patients. RAO immediately after clamp removal was documented in 14 (4.9%) and 8 (2.8%) patients in the 20- and 60-minute clamp application groups, respectively (P=0.19). The incidence of grade 1 hematoma was higher in the 20-minute group (6.7% versus 2.5%, P=0.015). RAO at 1 week after the procedure was 2.9% and 0.9% in the 20- and 60-minute groups, respectively (P=0.36). Requirement for clamp retightening (36% versus 16%, P=0.01) was higher among patients who had RAO. Need for clamp retightening was the only independent predictor of RAO (P=0.04).

CONCLUSIONS

Ultrashort radial clamp application of 20 minutes is not preferable to a short duration of 60 minutes. The 60-minute clamp duration is safe and provides good access site hemostasis with low RAO rates.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02269722.

Radiotherapy-Induced Cardiac Implantable Electronic Device Dysfunction in Patients With Cancer

Radiotherapy can affect the electronic components of a cardiac implantable electronic device (CIED) resulting in malfunction and/or damage. We sought to assess the incidence, predictors, and clinical impact of CIED dysfunction (CIED-D) after radiotherapy for cancer treatment. Clinical characteristics, cancer, different types of CIEDs, and radiation dose were evaluated. The investigation identified 230 patients, mean age 78 ± 8 years and 70% were men. A total of 199 patients had pacemakers (59% dual chamber), 21 (9%) cardioverter-defibrillators, and 10 (4%) resynchronizators or defibrillators. The left pectoral (n = 192, 83%) was the most common CIED location. Sixteen patients (7%) experienced 18 events of CIED-D after radiotherapy. Reset to backup pacing mode was the most common encountered dysfunction, and only 1 (6%) patient of those with CIED-D experienced symptoms of atrioventricular dyssynchrony. Those who had CIED-D tended to have a shorter device age at the time of radiotherapy compared to those who did not (2.5 ± 1.5 vs 3.8 ± 3.4 years, p = 0.09). The total dose prescribed to the tumor was significantly greater among those who had CIED-D (66 ± 30 vs 42 ± 23 Gy, p <0.0001). Multivariate logistic regression analysis identified the total dose prescribed to the tumor as the only independent predictor for CIED-D (odds ratio 1.19 for each increase in 5 Gy, 95% confidence interval 1.08 to 1.31, p = 0.0005). In conclusion, in this large population of patients with CIEDs undergoing radiotherapy for cancer treatment, the occurrence of newly diagnosed CIED-D was 7%, and the reset to backup pacing mode was the most common encountered dysfunction. The total dose prescribed to the tumor was a predictor of CIED-D. Importantly, although the unpredictability of CIEDs under radiotherapy is still an issue, none of our patients experienced significant symptoms, life-threatening arrhythmias, or conduction disorders.