AHA Journals, Author Interviews, Heart Disease, Outcomes & Safety, UT Southwestern / 04.12.2016
Delayed Epinephrine Linked To Worse Survival From In-Patient Cardiac Arrest
MedicalResearch.com Interview with:
Rohan Khera, MD
Cardiology Fellow, T32 Clinical-Investigator Pathway
UT Southwestern Medical Center
Dallas, TX
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Nearly 200 thousand people have an in-hospital cardiac arrest in the US each year. Of these, the vast majority have a non-shockable initial rhythm – either pulseless electric activity (PEA) or asystole. The survival of this type of arrest remains poor at around 12-14%. Moreover, even after accounting for differences in case mix, there is a wide variation in survival across hospitals – and this serves as a potential avenue for targeting quality improvement strategies at poor performing hospitals.
Recent data suggest that a shorter time from the onset of cardiac arrest to the first dose of epinephrine is independently associated with higher survival. Against this background of wide hospital variation in cardiac arrest survival, and patient-level data suggesting an association between time to epinephrine and patient survival, we wanted to assess (A) if there were differences in time to epinephrine administration across hospitals, and (B) if a hospital’s rate of timely epinephrine use was associated with its cardiac arrest survival rate. Within Get With The Guidelines-Resuscitation, we identified nearly 104-thousand adult patients at 548 hospitals with an in-hospital cardiac arrest attributable to a non-shockable rhythms. delays to epinephrine,
We found that (a) proportion of cardiac arrests with delayed epinephrine markedly across hospitals, ranging from no arrests with delay (or 0%) to more than half of arrests at a hospital (54%).
There was an inverse correlation between a hospital’s rate of delayed epinephrine administration and its risk-standardized rate of survival to discharge and survival with functional recovery - compared to a low-performing hospitals, survival and recovery was 20% higher at hospitals that performed best on timely epinephrine use.




Dr. Audrey Chang[/caption]
MedicalResearch.com Interview with:
Dr. Audrey Chang, PhD
Kamm-Stull Lab
UT Southwestern Medical Center
AudreyN.Chang@UTSouthwestern.edu
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: The heart is a singular kind of muscle that contracts and relaxes continuously over a lifetime to pump blood to the body’s organs. Contractions depend on a motor protein myosin pulling on actin filaments in specialized structures. Heart contraction is improved when myosin has a phosphate molecule attached to it (phosphorylation), and a constant amount of phosphorylation is essential for normal heart function. The amount of phosphorylation necessary for optimal cardiac performance is maintained by a balance in the activities of myosin kinase enzymes that add the phosphate and an opposing phosphatase enzyme that removes the phosphate. If the amount of phosphorylation is too low, heart failure results. Animal models with increased myosin phosphorylation have enhanced cardiac performance that resist stresses that cause heart failure.
In this recent study reported in PNAS, a new kinase that phosphorylates myosin in heart muscle, MLCK4, was discovered and its crystal structure reported, a first for any myosin kinase family member. Compared to distinct myosin kinases in other kinds of muscles (skeletal and smooth), this cardiac-specific kinase lacks a conserved regulatory segment that inhibits kinase activity consistent with biochemical studies that it is always turned on. Additionally, another related myosin kinase found only in heart muscle (MLCK3) contains a modified regulatory segment, allowing partial activity enhanced by the calcium modulator protein, calmodulin. Thus, both myosin kinases unique to cardiac muscle provide phosphate to myosin in normal beating hearts to optimize performance and prevent heart failure induced by stresses.

Dr. Ambarish Pandey[/caption]
Ambarish
MedicalResearch.com Interview with:
Ambarish Pandey M.D.
Division of Cardiology
University of Texas Southwestern Medical Center
Dallas, TX
Medical Research: What is the background for this study? What are the main findings?
Dr. Pandey: Pulmonary artery (PA) catheters have been used for invasive bedside hemodynamic monitoring for past four decades. The ESCAPE trial, published in October 2005, demonstrated that use of Pulmonary Artery catheter was not associated with a significant improvement in clinical outcomes of patients with heart failure. Accordingly, the current ACC/AHA guidelines discourage the routine use of PA catheter for routine management of acute heart failure in absence of cardiogenic shock or respiratory failure (Class III). Despite the significant evolution of available evidence base and guideline recommendations regarding use of Pulmonary Artery catheters, national patterns of PA catheter utilization in hospitalized heart failure patients remain unknown.
In this study, we observed that use of PA catheter among patients with heart failure decline significantly in the Pre-ESCAPE era (2001 – 2006) followed by a consistent increase in its use in the Post-ESCAPE era (2007-2012). We also observed that the increase in use of Pulmonary Artery catheters is most significant among heart failure patients without underlying cardiogenic shock or respiratory failure.














