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Author Interview:
Author Interview: Renato Delascio Lopes, MD, PhD, MHS
Duke University Medical Center
Duke Clinical Research Institute
Box 3850, 2400 Pratt Street, Room 0311
Terrace Level, Durham, NC 27705
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Publication:
Author Interview: Renato Delascio Lopes, MD, PhD, MHS
Diagnosing Acute Myocardial Infarction in Patients With Left Bundle Branch Block.
Lopes RD, Siha H, Fu Y, Mehta RH, Patel MR, Armstrong PW, Granger CB.
Am J Cardiol. 2011 Jul 2.
Duke Clinical Research Institute, Duke University Medical Center, Durham, North Carolina.
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What are the main findings of the study?
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The main finding of our study was that a substantial proportion of patients with LBBB had acute MI with a culprit lesion and positive biomarkers.
Documented MI (elevated biomarkers) with an initially occluded infarct artery was more common in patients with LBBB with concordant ST-segment elevation (71.4%) than in patients without concordant ST-segment elevation (44.1%).
The use of ST-segment elevation concordance criteria in the presence of LBBB was more often associated with documented MI with an identifiable culprit vessel with an initially occluded infarct-related artery.
Importantly, these data support immediate catheterization with the intent for primary percutaneous coronary intervention for all patients presenting with suspected ST-segment elevation myocardial infarction, ischemic symptoms, and presumed new LBBB, particularly if concordant ST-segment elevation is present.
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Were any of the findings unexpected?
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Maybe the lower rates of adverse outcomes at 90 days found in patients with LBBB with concordant ST-segment elevation compared to those with LBBB without concordant ST-segment elevation was an unexpected finding in our study. This could have been due to the small number of events plus the earlier intervention time coupled with MI location seen in those patients with LBBB with concordant ST-segment elevation.
As a surprising and important finding, most patients who present with LBBB still had it at discharge, which raises questions about how many of these patients might have had old LBBB and whether reinfarction with a newly occluded artery will be adequately assessed according to the designation of old versus new LBBB.
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What should clinicians and patients take away from this study?
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Again, the main finding is that a substantial proportion of patients with LBBB had acute MI with a culprit lesion and positive biomarkers. In our study, 13.3% of the patients with LBBB had negative biomarkers, 14.3% did not have a culprit artery, and 1% had no significant coronary artery disease. Importantly, when concordant ST-segment elevation was present in the setting of LBBB, the rates of false activation using these 3 criteria were lower (9.6%, 7.7%, and 0%, respectively).
In addition, when concordant ST-segment elevation was present, PCI or CABG surgery (overall and within 24 hours) was performed more frequently than when LBBB was present without concordant ST-segment elevation Thus, the use of a simple criteria such as concordant ST-segment elevation in patients with acute MI, ischemic symptoms and LBBB can help decreasing the rates of false activation of the catheterization laboratory and identifying patients more likely to need a revascularization procedure such as PCI or CABG surgery.
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What recommendations do you have for nephrology health care providers as a result of your study?
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In patients presenting with ischemic symptoms, presumed new left bundle branch block (LBBB) is considered to be equivalent to ST-segment elevation warranting acute reperfusion.
Because of uncertainty around LBBB as a marker of ST-segment elevation myocardial infarction (STEMI), its presence often results in delays in diagnosis and/or reperfusion or even in misdiagnosis. Thus, the use of ST-segment elevation concordance criteria in the presence of LBBB was more often associated with a documented MI with an identifiable culprit vessel with an initially occluded infarct-related artery.
However, since a substantial proportion of patients with LBBB have an acute MI with culprit lesion and positive biomarkers regardless this criteria, our findings support immediate catheterization, subject to its availability, with intent for primary PCI for all patients presenting with suspected STEMI, ischemic symptoms, and presumed “new” LBBB, but particularly if concordant ST-segment elevation is present.
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Abstract: |
We compared the clinical features, laboratory and coronary angiographic findings, treatments, and outcomes among patients with ST-segment elevation myocardial infarction (MI) with and without left bundle branch block (LBBB).
We examined 5,742 patients with ST-segment elevation MI with and without LBBB treated with primary percutaneous coronary intervention in the Assessment of Pexelizumab in Acute Myocardial Infarction trial. The main outcome measures were obstructive coronary disease, MI, positive cardiac biomarkers, angiographic Thrombolysis In Myocardial Infarction flow, and death, MI, or congestive heart failure at 90 days. LBBB was present in 98 patients (1.7%).
According to the protocol, patients with LBBB were eligible only if they had ≥1 mm concordant ST-segment elevation. Obstructive coronary artery disease was present in >87% of the patients with LBBB. Documented MI (elevated biomarkers) with an initially occluded infarct artery was more common in patients with LBBB with concordant ST-segment elevation (71.4%) than in patients without (44.1%; p = 0.027).
The use of ST-segment elevation concordance criteria in the presence of LBBB was more often associated with documented MI with an identifiable culprit vessel with an initially occluded infarct-related artery. In conclusion, because a substantial proportion of patients with LBBB have acute MI with a culprit lesion and positive biomarkers, these data support immediate catheterization with the intent for primary percutaneous coronary intervention for all patients presenting with suspected ST-segment elevation myocardial infarction, ischemic symptoms, and presumed new LBBB, particularly if concordant ST-segment elevation is present.
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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
| Chest Pain
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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