Genetics of coronary artery disease and myocardial infarction

Atherosclerotic coronary artery disease(CAD) comprises a broad spectrum of clinical entities that include asymptomatic subclinical atherosclerosis and its clinical complications, such as angina pectoris, myocardial infarction(MI) and sudden cardiac death. CAD continues to be the leading cause of death in industrialized society. The long-recognized familial clustering of CAD suggests that genetics plays a central role in its development, with the heritability of CAD and MI estimated at approximately 50% to 60%. Understanding the genetic architecture of CAD and MI has proven to be difficult and costly due to the heterogeneity of clinical CAD and the underlying multi-decade complex pathophysiological processes that involve both genetic and environmental interactions. This review describes the clinical heterogeneity of CAD and MI to clarify the disease spectrum in genetic studies, provides a brief overview of the historical understanding and estimation of the heritability of CAD and MI, recounts major gene discoveries of potential causal mutations in familial CAD and MI, summarizes CAD and MIassociated genetic variants identified using candidate gene approaches and genome-wide association studies(GWAS), and summarizes the current status of the construction and validations of genetic risk scores for lifetime risk prediction and guidance for preventive strategies. Potential protective genetic factors against the development of CAD and MI are also discussed. Finally, GWAS have identified multiple genetic factors associated with an increased risk of in-stent restenosis following stent placement for obstructive CAD. This review will also address genetic factors associated with in-stent restenosis, which may ultimately guide clinical decision-making regarding revascularization strategies for patients with CAD and MI.

Acute coronary syndrome in the older adults

Coronary heart disease remains the leading cause of death in the developed world. Advanced age is the single strongest risk factor for coronary artery disease （CAD） and independent predictor for poor outcomes following an acute coronary syndrome （ACS）. ACS refers to a spectrum of conditions compatible with acute myocardial ischemia and/or infarction due to various degrees of reduction in co- ronary blood flow as a result of plaque rupture/erosion and thrombosis formation or supply and demand mismatch.

Stable ischemic heart disease in the older adults

1 Introduction Ischemic heart disease is caused by atherosclerotic and/or thrombotic obstruction of coronary arteries. Clinical spec- trum of ischemic heart disease expands from asymptomatic atherosclerosis of coronary arteries to acute coronary syn- dromes （ACS） including unstable angina, acute myocardial infarction （non-ST elevation myocardial infarction and ST elevation myocardial infarction）. Stable ischemic heart dis- ease （SIHD） refers to patients with known or suspected SIHD who have no recent or acute changes in their symp- tomatic status, suggesting no active thrombotic process is underway.

Cardiac implications of thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura(TTP) is a multisystem disorder that essentially can affect any organ in the human body. The hallmark of the pathogenesis in TTP is the large von Willebrand factor multimers on plateletmediated micro-thrombi formation, leading to microvascular thrombosis.Autopsy studies showed that cardiac arrest and myocardial infarction are the most common immediate causes of death in these patients. Clinical manifestations of cardiac involvement in TTP vary dramatically, from asymptomatic elevation of cardiac biomarkers, to heart failure, MI and sudden cardiac death. There is limited knowledge about optimal cardiac evaluation and management in patients with TTP. The absence of typical cardiac symptoms,combined with complicated multi-organ involvement in TTP, may contribute to the under-utilization of cardiac evaluation and treatment. Prompt diagnosis and timely initiation of effective therapy could be critically important in selected cases. Based on our experience and this review of the literature, we developed several recommendations for focused cardiac evaluation for patients with acute TTP:(1) patients with suspected or confirmed TTP should be screened for the potential presence of cardiac involvement with detailed history and physical,electrocardiogram and cardiac enzymes;(2) clinical deterioration of TTP patients warrants immediate cardiac reevaluation;(3) TTP patients with clinical evidence of cardiac involvement should be monitored for telemetry, cardiac biomarkers and evaluated with transthoracic echocardiography. These patients require urgent targeted TTP treatment as well as cardiac-specific treatment. Aspirin therapy is indicated for all TTP patients. Since epicardial coronary artery involvement is rare, cardiac catheterization is usually not required, given the high risk for hemorrhage and kidney injury;(4) we recommend evidence-based medical therapy for ischemic symptoms and heart failure. TTP patients with evidence of cardiac involvement would also benefit from routine cardiology follow up during remission.

Cardiovascular physiology in the older adults

1 Introduction In an aging society with persistent high prevalence of cardiovascular disease （CVD） in the elderly population, the health care system is facing an increasing challenge to effectively care for these patients. However, due to the under-representation of CVD patients over 75 years of age in clinical trials, assessing safety and efficacy of diagnostic and therapeutic approaches, the evidence for managing elderly CVD patients is especially limited. Physiological changes of aging intertwined with pathophysiology of CVD, and comorbid conditions often complicate clinical management.

Plaque herniation after stenting the culprit lesion with myocardial bridging in ST elevation myocardial infarction: A case report

BACKGROUND Myocardial bridging(MB)is increasingly recognized to stimulate atherogenesis,which may contribute to an acute coronary syndrome.Stenting the coronary segment with MB has been recognized to have an increased risk of in-stent restenosis,stent fracture and coronary perforation.The safety and efficacy of stenting the culprit lesion with overlaying MB in ST elevation myocardial infarction(STEMI)as primary reperfusion therapy has not been established.CASE SUMMARY We reported a patient who presented with inferior STEMI with a culprit lesion of an acute thrombotic occlusion in the right coronary artery and thrombolysis and thrombin inhibition in myocardial infarction 0 flow.After the stent placement during primary percutaneous coronary intervention,intravascular ultrasound revealed MB overlying the stented segment where heavy atherosclerotic plaque were present.Likely due to the combination of plaque herniation or prolapse caused by MB,as well as local increased inflammation and thrombogenicity,acute stent thrombosis occurred at this region,which led to acute stent failure.The patient required an emergent repeated cardiac catheterization and placing a second layer of stent to enhance the radial strength and reduce the inter-strut space.CONCLUSION Plaque herniation or prolapse after stenting a MB segment in STEMI is a potential etiology for acute stent failure.

Intra-procedural arrhythmia during cardiac catheterization: A systematic review of literature

BACKGROUND Cardiac catheterization is among the most performed medical procedures in the modern era.There were sporadic reports indicating that cardiac arrhythmias are common during cardiac catheterization,and there are risks of developing serious and potentially life-threatening arrhythmias,such as sustained ventricular tachycardia(VT),ventricular fibrillation(VF)and high-grade conduction disturbances such as complete heart block(CHB),requiring immediate interventions.However,there is lack of systematic overview of these conditions.AIM To systematically review existing literature and gain better understanding of the incidence of cardiac arrhythmias during cardiac catheterization,and their impact on outcomes,as well as potential approaches to minimize this risk.METHODS We applied a combination of terms potentially used in reports describing various cardiac arrhythmias during common cardiac catheterization procedures to systematically search PubMed,EMBASE and Cochrane databases,as well as references of full-length articles.RESULTS During right heart catheterization(RHC),the incidence of atrial arrhythmias(premature atrial complexes,atrial fibrillation and flutter)was low(<1%);these arrhythmias were usually transient and self-limited.RHC associated with the development of a new RBBB at a rate of 0.1%-0.3%in individuals with normal conduction system but up to 6.3%in individuals with pre-existing left bundle branch block.These patients may require temporary pacing due to transient CHB.Isolated premature ventricular complexes or non-sustained VT are common during RHC(up to 20%of cases).Sustained ventricular arrhythmias(VT and/or VF)requiring either withdrawal of catheter or cardioversion occurred infrequently(1%-1.3%).During left heart catheterizations(LHC),the incidence of ventricular arrhythmias has declined significantly over the last few decades,from 1.1%historically to 0.1%currently.The overall reported rate of VT/VF in diagnostic LHC and coronary angiography is 0.8%.The risk of VT/VF was higher during percutaneous coronary interventions for stable coronary artery disease(1.1%)and even higher for patients with acute myocardial infarctions(4.1%-4.3%).Intravenous adenosine and papaverine bolus for fractional flow reserve measurement,as well as intracoronary imaging using optical coherence tomography have been reported to induce VF.Although uncommon,LHC and coronary angiography were also reported to induce conduction disturbances including CHB.CONCLUSION Cardiac arrhythmias are common and potentially serious complications of cardiac catheterization procedures,and it demands constant vigilance and readiness to intervene during procedures.