General cardiology

Circulation now based at UT Southwestern

By Joseph A. Hill, M.D., Ph.D.
Chief, UT Southwestern Division of Cardiology

Joseph A. Hill, M.D., Ph.D.
Joseph A. Hill, M.D., Ph.D.

In April 2015, I was selected Editor-in-Chief of Circulation, the leading journal in cardiovas­cular medicine. This responsibility is an enor­mous tribute to the strengths of research, clinical care, and teaching at UT Southwestern. 

Our team subsequently spent the next nine months implementing our vision and recruiting a large team of editors from around the globe. By early 2016, our UT Southwestern-based edito­rial team assumed handling some of the papers coming in, and we began to recruit a broad range of novel content. In July of this year, the journal transitioned formally from Harvard to UT Southwestern.

Circulation is a high-volume, weekly journal. It receives 80 to100 papers per week and pub­lishes five of them in each issue. Our team has launched a wide range of novel content types. We supervise a team of three Senior Editors, 40 Associate Editors, 20 Content Editors, and nine staff members, and we have recruited an Edito­rial Board comprising approximately 250 leaders from around the world.

One of our major initiatives with Circulation has been to vastly enhance its global footprint. Rather than having all our Associate Editors in one city – as the prior model did – we now have one-third located in Dallas, one-third in the U.S. outside of Dallas, and one-third outside the U.S. In fact, Circulation now has leaders positioned in 14 countries! And our team does not have “international editors”– we have “editors,” each of whom has the same role, the same seat at the leadership table, as those in Dallas. Through weekly videoconferencing, our group benefits from insights, ideas, and energy derived – quite literally – from around the world.

At AHA Scientific Sessions this year in New Orleans, we continued a proud tradition of leading a Sunday morning session highlighting the outstanding content published in Circulation, focusing on content that is emblematic of the type and spirit we will emphasize going forward. We recruited Drs. Eugene Braunwald (Harvard TIMI group) and Robert Califf (Commissioner, Food and Drug Administration) to present at this exciting session. Further, in a program that mirrored the layout of our journal, we hosted speakers and panelists across the wide range of content Circulation currently hosts.

“At AHA Scientific Sessions this year in New Orleans, we continued a proud tradition of leading a Sunday morning session highlight­ing the outstanding content published in Circulation, focus­ing on content that is emblematic of the type and spirit we will emphasize going forward.”

Measuring troponin in an outpatient setting: what we’re learning

By James de Lemos, M.D.
Professor of Internal Medicine

James de Lemos, M.D.
James de Lemos, M.D.

While acute elevations of troponins are the preferred biomarkers for diagnosis of myocardial infarction in the emergency room and hospital setting, at UT Southwestern we have been studying the impact of chronic troponin elevations for the past decade. In 2006, using the cardiac troponin T (cTnT) assay still favored today, we published findings in Circulation suggesting that, even among apparently healthy adults, a very small elevation in troponin levels may be seen and, when detected, used to identify individuals who may have unrecognized structural heart disease.

The development of high-sensitivity (hs) troponin assays has expanded the possible applications of troponin testing in multiple new directions, including potentially the outpa­tient office visit. With the hs assay, cTnT can be detected at very low concentrations in more than 90 percent of outpatients with stable chronic heart failure or coronary artery disease (CAD). In these chronic conditions, dose-dependent asso­ciations have been observed between troponins and both heart failure and the subsequent risk for death at levels well below the detection threshold of standard assays.

These hs assays also have opened the door to the potential of risk assessment using troponin measurements in people without known CAD. My team and I assessed hs-cTnT in three large ep­idemiological cohorts totaling more than 17,500 individuals. Concentrations of cTnT increased with age and were higher in men, African-Amer­icans, and those with chronic kidney disease. High-sensitivity cTnT levels demonstrated strong associations with pathological cardiac remodel­ing, as levels increased in parallel with the pres­ence and severity of left ventricular hypertrophy and left ventricular systolic dysfunction.

The risk identified by small elevations in hs-cTnT appears to be modifiable, as people who have increases in cardiac troponin during outpa­tient follow-up are at higher risk for heart failure, whereas the risk is lower among those whose levels fall over time. To date, only limited data are available regarding the factors that might favor­ably influence troponin levels in the population.

Preliminary findings suggest that higher levels of baseline physical activity and fitness are associated with favorable trends in troponin levels over time. Although these early findings from large epidemiological cohorts are promising, much work needs to be done before office-based applications of hs-troponin assays are considered. Further research is needed to identify treatments that prevent additional cardiac injury and modify risks associated with elevated troponin levels.

“The development of high-sensitivity (hs) troponin assays has expanded the possible applications of tropo­nin testing in multiple new directions, includ­ing potentially the outpatient office visit.”

Glucose control for patients with acute coronary syndromes

By Darren McGuire, M.D., M.H.Sc.
Professor of Internal Medicine

Darren McGuire, M.D., M.H.Sc.
Darren McGuire, M.D., M.H.Sc.

The role of myocardial metabolic modula­tion during acute coronary syndrome (ACS) events has been investigated for de­cades, with almost all completed trials evaluating high-dose IV insulin (e.g., 5u/hr), with IV dextrose administered to avoid hypoglycemia and protocol targets of hyperglycemia (126-198 mg/dL) – a strategy termed “Glucose-Insulin-Potassium,” or GIK therapy.

The CREATE ECLA GIK trial ultimately proved GIK therapy futile for ACS management. That trial comprised 20,201 patients with ST-elevation MI (STEMI) who were randomized to receive GIK therapy versus usual care. The GIK group showed no benefit compared to those who received usual care, and subsequently the concept of GIK treatment for ACS was abandoned.

With regard to targeted glucose control, no clinical outcome trial has ever been done in the ACS/acute myocardial infarction (AMI) setting. We are thus left extrapolating data from clinical trials of non-ACS ICU patient populations to inform clinical care.

Recommendations for glucose control first entered the ACCF/AHA guidelines in 2000 for NSTEMI and in 2004 for STEMI, calling for “nor­malization of blood glucose with IV insulin.” But the guideline writers made a serious mistake, basing their recommendations on the results of the DIGAMI trial that had used the GIK dosing strategy of hyperinsulinemia/hyperglycemia, which neither targeted glucose control nor normalization of blood glucose as part of the trial intervention.

Over the following two decades, ACS guide­lines have significantly evolved to recommend increasingly more liberal glucose targets. This evo­lution has been based on neutral or even adverse effects on mortality of IV insulin-targeting normal blood glucose seen in five large-scale randomized trials of ICU populations, along with high rates of severe hypoglycemia observed with IV insulin.

Both ACCF/AHA and ESC guidelines for ACS/AMI currently advocate IV insulin to target glucose ­levels <180mg/dl (i.e., permissive hyperglycemia), and they underscore the importance of hypogly­cemia avoidance. Since 2012, this same target has been endorsed in endocrinology guidelines and is also reflected in cardiac surgery guidelines for patients undergoing cardiac surgery.

Therefore, until further evidence becomes available, we should no longer be targeting intensive glucose control/normalization of blood glucose in the acute management phase of myocardial infarction, with a target of 180mg/dl being most prudent.

“Until further evidence becomes available, we should no longer be targeting intensive glucose control/normalization of blood glucose in the acute management phase of myocardial infarction.”

 

Physician Referral Information

UT Southwestern welcomes referrals from providers seeking optimal care for heart patients. Physicians and offices can refer a patient with one easy call to the heart intake coordinator, a registered nurse who is available 24 hours a day, seven days a week. Same-day access is available for patients experiencing chest pain and chest discomfort. To refer a patient to any UT Southwestern clinic or for general inquiries, call Patient and Physician Referral Services at 214-645-8300.

Clinical Heart Center Patient Referrals

Phone: 855-240-0816
Fax: 214-645-7269

Questions or Comments

If you have any questions or would like more information about the Clinical Heart Center or the recent AHA Scientific Sessions, contact Dr. Mark Drazner, Clinical Chief of Cardiology, at mark.drazner@utsouthwestern.edu.

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