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CARDIOVASCULAR NEWS
Year : 2006  |  Volume : 7  |  Issue : 3  |  Page : 84-87 Table of Contents     

Cardiovascular News


Date of Web Publication17-Jun-2010

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How to cite this article:
. Cardiovascular News. Heart Views 2006;7:84-7

How to cite this URL:
. Cardiovascular News. Heart Views [serial online] 2006 [cited 2022 Jan 20];7:84-7. Available from: https://www.heartviews.org/text.asp?2006/7/3/84/63917

Long-term Survival in Patients Presenting with Type B Acute Aortic Dissection: Insights from the International Registry of Acute Aortic Dissection

Survival in patients presenting with uncomplicated acute type B aortic dissection is generally good, and hospital discharge is approximately 90%. In patients with a more complex presentation, morbidity and mortality may be significantly higher. Long-term follow-up of patients with type B aortic dissection has been limited and confined to a few small series. The International Registry of Aortic Dissection (IRAD) provides useful long-term follow-up of a contemporary series of patients with type B dissection. T. Tsai et al report on a cohort of patients from centers with good postdischarge surveillance. At a median follow-up of 2.3 years, survival for patients treated medically, surgically, or with endovascular therapy was 77.6 6.6%, 82.8 18.9%, and 76.2 25.2% respectively. Independent predictors of follow-up mortality included female gender, history of prior aortic aneurysm, history of atherosclerosis, in-hospital renal failure, and pleural effusion on chest x-ray and in-hospital hypotension/shock. Even with contemporary approaches to treatment of type B aortic dissection, the 3-year mortality rate approaches one in every four patients. Strategies to improve long-term outcome in patients with type B dissection need to be developed.

Bedside Tool for Predicting the Risk of Postoperative Dialysis in Patients Undergoing Cardiac Surgery

The use of a large clinical database allows unique opportunities for clinical research. The Society of Thoracic Surgeons' National Cardiac Database is the largest cardiac surgery database in the world, providing a rich source of information. Using this database, Mehta et al studied renal failure after cardiac surgery requiring dialysis. The authors evaluated data of 449,524 patients undergoing coronary artery bypass grafting (CABG) and/or valve surgery and enrolled in > 600 hospitals participating in the Society of Thoracic Surgeons National Database (2002-2004).

Based on multiple preoperative clinical factors, a means of estimating a patient's individual risk for postoperative dialysis was developed using a bedside additive risk tool. Patients needing postoperative dialysis were 1.5- to 5.0-fold more likely to have comorbid preoperative conditions, including diabetes mellitus, chronic lung disease, peripheral or cerebrovascular disease, recent myocardial infarction, congestive heart failure, prior bypass or valve surgery, cardiopulmonary resuscitation, and cardiogenic shock (all P < 0.0001). The incidence of postoperative dialysis also rose with increasing preoperative serum creatinine (and decreasing GFR) measurements.

The risk score accurately differentiated patients' need for postoperative dialysis across a broad risk spectrum and performed well in patients undergoing isolated CABG, off-pump CABG, isolated aortic valve surgery, aortic valve surgery plus CABG, isolated mitral valve surgery, and mitral valve surgery plus CABG (c statistic = 0.83, 0.85, 0.81, 0.75, 0.80, and 0.75, respectively).

Renal failure requiring the initiation of dialysis is a serious postoperative complication associated with higher mortality, poor quality of life, and increased hospital length of stay and resource utilization. The use of this clinical tool was developed to facilitate informed clinical decision making and patient counseling prior to surgery.

Coronary Multidetector Computed Tomography in the Assessment of Patients with Acute Chest Pain

Assessment of Emergency Department (ED) patients with suspected acute coronary syndromes (ACS) who have no obvious ischemic ECG changes and negative initial biomarker studies remains challenging. Rapid evaluation is important, as ruling in an ACS could lead to earlier treatment, while ruling out an ACS could lead to more rapid ED discharge. Hoffmann and colleagues present the initial report on the performance characteristics of multidetector computed tomographic angiography (CTA) in such patients. They report that the absence of stenosis or plaque on CTA has 100% negative predictive value for ruling out an ACS. Moreover, the extent of coronary plaque on CTA, when present, adds significant information to the probability of an ACS being present. Although requiring confirmation, these data usher in a potential new noninvasive paradigm for the evaluation of patients with suspected ischemic chest pain in the ED.

Biphasic Waveform Defibrillation not superior to the Monophasic Waveform

Shocks with a biphasic wave form are more effective than monophonic shocks for terminating ventricular fibrillation in many situations. All new defibrillators have biphasic waveforms, but a large number of monophasic waveform devices remain in use. Should replacement of these devices receive a high priority? Kudenchuk and colleagues conducted a randomized trial comparing monophasic and biphasic shocks for treatment of out-of-hospital cardiac arrests. A unique aspect of their trial was blinding of the investigators that extended through the data analysis and review process, unblinding only after the manuscript had been accepted for publication. Arrest victims received cardiopulmonary resuscitation before shock, consistent with present guidelines. Biphasic waveform defibrillation was not superior to the monophasic waveform, although a trend toward better survival did favor the biphasic waveform. The study should inform communities and institutions that are prioritizing resources for replacement of monophasic waveform defibrillators.

Ventricular Septal Defect and the Mustard Operation are Risk Factors for late Mortality after the Atrial Switch Operation

Many patients with transposition of the great vessels are surviving for decades after surgical repair. For decades, the surgical approach to transposition of the great vessels had been an atrial switch (Senning or Mustard) procedure. Currently, an arterial switch is the standard preferred procedure. The late results of procedures that are not in vogue today, however, are of importance in caring for the growing population of adults with repaired congenital cardiac defects. Lange et al, from a single center, reviewed 329 patients after a Senning Procedure and 88 after a Mustard operation with mean follow-up of 19 years.

Ventricular septal defect closure at the time of the atrial switch operation (hazard rate = 2.3; 95% confidence interval, 1.1 to 4.7; P = 0.025) and the Mustard operation (hazard rate = 2.0; 95% confidence interval, 1.01 to 3.8; P = 0.045) emerged as independent risk factors for late mortality in multivariate analysis. Patients who had undergone ventricular septal defect closure at the time of the atrial switch operation and those who had undergone a Mustard operation are at higher risk for late death. Close follow-up, especially of these subgroups, is warranted.

Impaired Chronotropic and Vasodilator Reserves Limit Exercise Capacity in Patients with Heart Failure and A Preserved Ejection Fraction

Clinicians and investigators in the field of heart failure recognize that approximately half of all heart failure patients have preserved ejection fraction (EF). Symptoms in those patients are most commonly ascribed to underlying abnormalities in diastolic function. Borlaug and colleagues challenge that conventional wisdom with unique findings. In a comprehensive study of patients with heart failure and preserved EF and a group of very well-matched referent controls, all studied at rest and during graded exercise, the investigators found that the limited exercise tolerance and blunted stress cardiac output in the patients with heart failure and preserved EF wass associated with blunted chronotropic reserve as well as abnormalities in peripheral systemic vasodilatation during stress. These novel data add complexity to the underlying pathophysiology of heart failure in the setting of preserved EF, and perhaps most important, suggest potential new avenues for treatment of this syndrome, for which little evidence-based therapy exists.

Short-term Treatment with Anti-CD3 Antibody Reduces the Development and Progression of Atherosclerosis in Mice

It is now generally recognized that atherosclerosis is a chronic inflammatory disease that can lead to severe clinical events after plaque rupture and thrombosis. Prevention and current treatments for atherosclerosis are based mainly on drugs that decrease plasma cholesterol concentrations and lower heightened blood pressure. In particular, statins have proved to reduce cardiovascular events significantly, not only by their cholesterol-lowering properties but also by their more recently identified antiinflammatory and immunomodulatory effects.

Anti-CD3-specific antibodies suppress immune responses by antigenic modulation of the CD3 antibody/T-cell receptor complex. Their unique capacity to restore self-tolerance in a mouse model of diabetes and, importantly, in patients with recent-onset type 1 diabetes involves transforming growth factor-?-dependent mechanisms via expansion and/or activation of regulatory T cells. Steffens et al hypothesized that treatment with anti-CD3-specific antibodies might inhibit atherosclerosis development and progression in mice.

The investgators found that Anti-CD3 antibody therapy reduced plaque development when administered before a high-cholesterol diet and markedly decreased lesion progression in mice with already established atherosclerosis. They found increased production of the anti-inflammatory cytokine transforming growth factor-? in anti-CD3 antibody-treated mice. The results from this study suggest that pretreatment with ARB prevents cardiac dysfunction and attenuates the LV dilatation seen in acute MI.

Peripheral Arterial Disease in Patients with end-stage Renal Disease: Observations from the Dialysis Outcomes and Practice Patterns Study (DOPPS)

Patients with end-stage renal disease and patients with peripheral arterial disease are both at high risk for cardiovascular morbidity and mortality. Rajagopalan and colleagues examined a large international cohort of hemodialysis patients to understand the prevalence and prognosis of peripheral arterial disease in hemodialysis patients. The data in the study were derived from the Dialysis Outcomes and Practice Patterns Study (DOPPS), a prospective, international, observational study of adult hemodialysis patients.

Although they observed significant international variation, the investigators report a poor prognosis in the 25% of patients with peripheral arterial disease. Their research revealed an approximately 40% increased risk of cardiac and all-cause mortality and a doubling of cardiovascular events in hemodialysis patients, who already experience significant risk because of their end-stage kidney disease. This is the first study to provide detailed international comparisons of PAD and its correlates in the hemodialysis patient population. PAD is common in hemodialysis patients and is associated with increased risk of cardiovascular mortality, morbidity and hospitalization, and reduced HRQOL. These findings provide new insights into a subgroup of patients on hemodialysis who may need special medical and social attention.

Antisense Inhibitor Reduces Apolipoprotein B and Low Density Lipoprotein

Over the last 2 decades, there has been a revolution in our understanding of gene regulation. Nevertheless, there has been little application of this understanding to clinical medicine. Kastelein and colleagues describe the use of a relatively new technique, administration of antisense nucleotides, to modulate circulating low-density lipoprotein levels. This report represents an important milestone in the application of molecular techniques to patient care and cardiovascular medicine.

Pretreatment with Angiotensin Receptor Blockade Prevents Left Ventricular Dysfunction and Blunts Left Ventricular Remodeling Associated with Acute Myocardial Infarction

Although blocking activation of the renin-angiotensin system (RAS) after a myocardial infarction (MI) is standard treatment to reverse maladaptive left ventricular (LV) remodeling, the efficacy of this treatment as a preventive modality is unclear. Recent clinical trials have proposed a preventive strategy with blockade of the RAS in patients at risk for atherosclerotic heart disease to prevent ischemic events and to improve cardiovascular morbidity/mortality. However, many patients treated with an angiotensin-converting enzyme inhibitor (ACEI) and/or angiotensin receptor blocker (ARB) will still go on to have a MI. The hypothesis is that pretreating patients with neurohormonal blockade will attenuate maladaptive LV remodeling at the time of the acute infarct. This assumption would be difficult to study in clinical trials.

H. Thai et al examined this hypothesis in the rat coronary artery ligation model of acute MI. The study was designed to determine the effects of pretreatment with an angiotensin receptor blocker on left ventricular (LV) function and remodeling during acute myocardial infarction (MI). Pretreatment with candesartan before an acute MI improves global LV function, prevents LV dilation, and blunts the increase in constitutive microtubulin, with minimal effects on LV hemodynamics, regional function, or tissue endothelial nitric oxide synthase. Thus, candesartan given before an MI attenuates LV remodeling and alters the cytoskeleton matrix of the left ventricle.



Gene Transfer of a Synthetic Pacemaker Channel into the Heart: A Novel Strategy for Biological Pacing

The use of ion-channel gene therapy for creating biological pacemakers has been an area of great interest, as electronic devices have limited longevity and are prone to lead failure, particularly in younger patients. Recent studies have used either the natural or genetically-modified hyperpolarization-activated nucleotide-gated channel gene in different animal models of sinus node dysfunction or atrioventricular block. Kashiwakura et al report their results of experiments using a novel bioengineered human Kv1.4 depolarization-activated potassium channel that functioned as a hyperpolarization-activated nonselective channel in guinea pigs. They demonstrate spontaneous electrical activity after transfection into the heart both in vitro on cellular preparations and in vivo by ECG. This synthetic pacemaker channel may allow more adaptability in heart rate control. Although biological pacemakers are not ready to replace electronic pacemakers, these studies further our understanding of cardiac impulse generation and demonstrate advances in gene therapy for electrophysiological abnormalities.

Catheter Ablation: First Line Therapy for Right Atrial Flutter in the Elderly?

Right atrial flutter is often recurrent despite antiarrhythmic drug therapy. It is effectively managed with catheter ablation, but atrial fibrillation, which may also warrant antiarrhythmic therapy, emerges in a substantial portion of patients during follow-up. Da Costa and colleagues conducted a randomized trial to compare catheter ablation to chronic therapy with amiodarone in elderly patients after their first episode of atrial flutter. Ablation was extremely effective in preventing recurrent atrial flutter, and was more effective than amiodarone. During follow-up treatment, amiodarone did not significantly lower the incidence of atrial fibrillation as compared with catheter ablation of the atrial flutter. These data support catheter ablation as a reasonable first line therapy for common right atrial flutter in the elderly. Whether such an approach would translate into less antiarrhythmic drug toxicity and fewer hospitalizations compared with cardioversion or other antiarrhythmic drug therapies warrants further study.

Failure to Identify High-Risk ECG in Acute Myocardial Infarction: Implications

The appropriate diagnosis and treatment of patients with an acute myocardial infarction depends largely on the correct interpretation of the electrocardiogram in the emergency department. Despite the importance of the skill of correctly interpreting the electrocardiogram, relatively little is known about the prevalence of misinterpretations and their consequences. This retrospective study by Masoudi et al examined the failure to identify high-risk electrocardiographic findings in patients presenting to 1 of 5 emergency departments in California and Colorado. The authors report the failure to identify important ST-segment depressions, elevations or T-wave inversions on the first electrocardiogram of patients with a confirmed acute myocardial infarction. They also investigated the association of the misinterpretations with the quality of patient care and in-hospital mortality. The present study identifies an important opportunity to improve care.






 

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