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An interview with Drs. Michael Bennett, Jan Lehm and Nigel Jepson
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Publication:
An interview with Drs. Michael Bennett, Jan Lehm and Nigel Jepson
HYPERBARIC OXYGEN THERAPY FOR ACUTE CORONARY SYNDROME
Bennett MH, Lehm JP, Jepson N. Hyperbaric oxygen therapy for acute coronary syndrome. Cochrane Database of Systematic Reviews 2011, Issue 8. Art. No.: CD004818. DOI: 10.1002/14651858.CD004818.pub3.
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What are the main findings of the study?
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This Cochrane meta-analysis was originally conducted in 2005 and most recently updated in Issue 8, 2011 of the Cochrane database of Systematic Reviews. We found six randomised controlled trials investigating the use of hyperbaric oxygen therapy (HBOT) for acute coronary syndrome (ACS). These trials included a modest total of 665 participants that have contributed to this review.
There was a significant decrease in the risk of death with HBOT (risk ratio (RR) 0.58, 95% CI 0.36 to 0.92, P = 0.02). The extent of heart muscle damage was lower following HBOT, as shown by a lesser rise in plasma creatine phosphokinase (CPK) (mean difference (MD) 493 IU, P = 0.005) and a better left ventricular ejection fraction (LVEF) (MD 5.5%, P = 0.001).
There was also evidence from individual trials of reductions in the risk of major adverse coronary events (MACE) (RR 0.12, P = 0.03); re-infarction over the subsequent year (RR 0.28, P = 0.04); dysrhythmias following HBOT (RR 0.59, P = 0.01); and the time to relief of pain was reduced with HBOT (MD 353 minutes shorter, P < 0.00001).
One trial suggested a significant incidence of claustrophobia in single occupancy chambers of 15% (RR of claustrophobia with HBOT 31.6, P = 0.02).
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Were any of the findings unexpected?
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The use of HBOT in the setting of an evolving ACS is not a routine therapeutic option available to most cardiologists, nor would the rationale be familiar to most practitioners. The findings would therefore be rather unexpected although the pathophysiological rationale is reasonably compelling.
It is of great interest that the small scale clinical trials conducted to date do indeed suggest that HBOT in this setting may be both life and myocyte saving. The results from individual trials all seem to confirm the possibility that HBOT may be indicated in this setting. Some (but not all) of these trials were conducted prior to the availability of either acute thrombolysis or interventional revascularisation, and more work is required to establish the place, if any, of HBOT in the modern therapeutic setting. There is a strong case for further clinical trials in this area.
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What should clinicians and patients take away from this study?
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HBOT involves patients breathing pure oxygen at high pressures in a specially designed chamber. It has been proposed as a useful adjunctive treatment both acutely during an episode of ACS where it may increase the supply of oxygen to the damaged heart, and before and after percutaneous coronary artery stenting where it may modify ischaemia reperfusion injury.
HBOT for ACS was first reported by Moon in 1964 and several uncontrolled human studies have been published since that time, generally with indications of benefit measured as a reduction in mortality or improvements in haemodynamic or metabolic parameters. This study has synthesised the randomised evidence.
Although relatively benign, HBOT is associated with some risk of adverse effects including damage to the ears, sinuses and lungs from the effects of pressure, temporary worsening of myopia, claustrophobia and oxygen poisoning. Serious injury is however very rare.
This study concludes there is some evidence from small trials to suggest that HBOT is associated with important improvements in outcome. However, in view of the modest number of patients, methodological shortcomings and poor reporting, this result should be interpreted cautiously, and an appropriately powered trial of high methodological rigour is justified to define those patients (if any) who can be expected to derive most benefit from HBOT. The routine application of HBOT to these patients cannot be justified at the current level of evidence.
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What recommendations do you have for nephrology health care providers as a result of your study?
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We recommend that cardiologists consider HBOT as a potentially useful intervention in ACS. While our results should be interpreted cautiously, we believe an appropriately powered trial of high methodological rigour is justified to define those patients (if any) who can be expected to derive most benefit from HBOT. Researchers in this area should review the mechanisms of actions of oxygen at high pressure and consider involvement in further work in this area.
Clinically, more information is required on the subset of disease severity and timing of therapy most likely to result in benefit from this therapy.
Given the activity of HBOT in modifying ischaemia-reperfusion injury, attention should be given to combinations of HBOT and thrombolysis in the early treatment of acute coronary events and the prevention of re-stenosis after stent placement.
Any future trials would need to consider in particular appropriate sample sizes with power to detect the expected differences suggested by this review; a careful definition and selection of target patients; acute versus sub-acute administration of HBOT; appropriate range of oxygen doses per treatment session (pressure and time); appropriate and carefully defined comparator therapy; use of an effective sham therapy; effective and explicit blinding of outcome assessors; appropriate outcome measures including all those listed in this review; careful elucidation of any adverse effects; and the cost-utility of therapy.
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Featured Angina| Acute Coronary Syndrome and Heart Disease Interviews
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Highlights of Article by Dr. Erik Hess et of Mayo Clinic ;CIRCOUTCOMES 2012
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Chest pain is the 2nd most common reason patients come to EDs across the United States
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Initial testing – including information obtained from the history, physical exam, electrocardiogram, and cardiac troponin – identifies > 98% of heart attacks
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To avoid missing a diagnosis of heart attack or pre-heart attack symptoms, emergency physicians often admit patients to observation units or to the hospital for extensive diagnostic testing, including stress testing
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This results in false positive test results, unnecessary exposure to radiation, and unnecessary downstream procedures such as stent placement in arteries of the heart
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Decision aids are evidence-based tools designed to educate and engage patients in decisions regarding their care
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We hypothesized that patients who were educated regarding their future risk for a heart attack and engaged in the decision of whether to be admitted to the observation unit for stress testing or to follow-up with a Mayo Clinic heart doctor in the next 72 hours would have greater knowledge about their short-term risk for heart attack, be more aware of the management options, and choose less intensive approaches to evaluation
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We randomly assigned 204 patients who came to the ED with chest pain and were being considered for observation unit admission to the decision aid or to usual care
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Decision aid patients:
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Had greater knowledge regarding their short-term risk for a heart attack
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Less frequently decided to be admitted to the observation unit for stress testing
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Had 4 times greater engagement in the decision making process
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Had no adverse events within 30 days of the ED visit
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Take home points
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Patients want to be educated and engaged in decisions regarding their care
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Once properly informed and engaged in treatment decisions, patients often choose less intensive treatment options
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Integrated health systems like the Mayo Clinic in which physicians collaboratively work together to provide ER patients ready access to outpatient follow-up have potential to improve the value of Emergency care
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Glucose, Insulin and Potassium (“GIK”) TO MINIMIZE IMPACT OF HEART ATTACKS BEFORE PATIENTS GET TO THE HOSPITAL
Study puts life-saving drugs in the hands of paramedics, decreasing rate of cardiac arrest and death from heart attacks
CHICAGO (March 27, 2012) — Paramedics can potentially reduce someone’s chances of having a cardiac arrest or dying by 50 percent by immediately administering a mixture of glucose, insulin and potassium (“GIK”) to people having a heart attack, according to research presented today at the American College of Cardiology’s 61st Annual Scientific Session. The Scientific Session, the premier cardiovascular medical meeting, brings cardiovascular professionals together to further advances in the field.
The study showed that patients who received GIK immediately after being diagnosed with acute coronary syndrome — which indicates a possible heart attack is either in progress or on the way — were 50 percent less likely to have cardiac arrest (a condition in which the heart suddenly stops beating) or die than those who received a placebo, although the treatment did not prevent the heart attack from occurring. The reduction in in-hospital cardiac arrest or death was a “secondary endpoint”, so statistically was not definitive, but was consistent with how GIK seems to work in experimental models of heart attack.
The effect was also present for patients with ST-elevation heart attacks, which require immediate treatment. For those patients, immediate GIK was associated with a 60 percent reduction in in-hospital cardiac arrest or death.
“When started immediately in the home or on the way to the hospital — even before the diagnosis is completely established — GIK appears not completely prevent any heart attack from occurring, but appeared in this trial to reduce the size of heart attacks and to reduce by half the risk of having a cardiac arrest or dying,” said Harry P. Selker, MD, MSPH, executive director of the Institute for Clinical Research and Health Policy Studies at Tufts Medical Center, who led the study with Joni Beshansky, RN, MPH, co-principal investigator and project director. “Acute coronary syndromes represent the largest cause of death in this country. GIK is a very inexpensive treatment that appears to have promise in reducing those deaths and morbidity.”
The cost of the treatment is about $50.
“Because the trial is the first to show GIK could be effective when used by paramedics in real-world community settings, it could have important implications for the treatment of heart attacks,” Dr. Selker said. Previous clinical trials have shown no consistent effect, likely because the GIK was given too late to help. This study, the “IMMEDIATE Trial,” was the first to test the effectiveness of administering GIK at the very first signs of a threatening heart attack, in the community, rather than waiting hours until the diagnosis was well-established at a hospital, as done in previous clinical trials.
“We wanted to do something that is effective and can be used anywhere,” said Dr. Selker. “We’ve done a lot of studies of acute cardiac care in emergency departments and hospitals, but more people die of heart attacks outside the hospital than inside the hospital. Hundreds of thousands of people per year are dying out in the community; we wanted to direct our attention to those patients.”
The researchers trained paramedics in 36 Emergency Medical Services systems in 13 cities across the country to administer GIK after determining that a patient was likely having a threatened or already established heart attack using electrocardiograph-based ACI-TIPI (acute cardiac ischemia time-insensitive predictive instrument) and thrombolytic predictive instrument decision support that prints patient-specific predictions on the top of an electrocardiogram. The paramedics used these predictions to decide if a patient would likely benefit from treatment. There were 911 patients randomized to receive either the GIK treatment or a placebo.
Administering GIK immediately also reduced the severity of the damage to the heart tissue from the heart attack. On average, 2 percent of the heart tissue was destroyed by the heart attack in people receiving GIK, compared with 10 percent in those who received the placebo. Although a significant proportion of suspected heart attacks are later determined to be false alarms (23 percent in this study), administering GIK does not appear to cause any harmful effects in such patients.
The research team will follow up with study participants at six and 12 months to evaluate the longer-term benefit of the GIK treatment.
This study was funded by the NIH’s National Heart, Lung and Blood Institute.
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Angina | Heart Disease Resourses
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Amazon.com 's Editorial Reviews
Angina: New Ways to Treat
Chronic Chest Pain
Part of the award winning public television series Healthy head
/Healthy Mind. It's one of the scariest medical symptoms for people who are generally healthy: a tightening, painful feeling in the chest known as Angina. In some cases this chest pain can be a serious warning that requires immediate treatment. But for the millions of people with chronic, stable angina the discomfort is something that can be readily managed with a variety of treatments. In this program we take a look at what generally causes angina, what can be done to prevent it and how it can be effectively treated with lifestyle changes, innovative drug therapies and medical procedures.
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Amazon.com Editorial Review:
Philips HeartStart Home Defibrillator (AED)
Be prepared for the unexpected.
When sudden cardiac arrest (SCA) strikes, the electrical system of the heart short circuits, causing the heart to quiver rather than pump in a normal rhythm. It typically results in the abnormal heart rhythm know as ventricular fibrillation (VF). It usually happens without warning and the majority of people have no previously recognized symptoms of heart disease. And it most often happens at home. For the best chance of survival from SCA caused by VF, a defibrillator should be used within 5 minutes. Yet, less than 1 in 20 people survive largely because a defibrillator does not arrive in time.
Just as seat belts or airbags do not save every life in a traffic accident, a defibrillator will not save every person who suffers a sudden cardiac arrest. Yet many lives could be saved if more people could be reached more quickly.
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