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When cardiac arrest occurs in the catheterization laboratory, the chances of survival has depended to a large extent on the facility, a national registry study showed.

Median risk-adjusted survival rates ranged from 20% to 52% at hospitals in the lowest and highest tertiles, respectively, cardiologist Deepak Bhatt, MD, MPH, of Icahn School of Medicine at Mount Sinai in New York City, and colleagues reported in .

The likelihood of survival for an otherwise identical patient varied by 71% when treated at one randomly chosen hospital versus another (median OR 1.71, 95% CI 1.52-1.87).

"Even in controlled settings such as the [cardiac catheterization laboratory], there is significant hospital-level variation in survival after in-hospital cardiac arrest, which suggests an important opportunity to improve resuscitation outcomes in procedural areas," the researchers concluded.

That there was significant variation in survival not only at discharge, but also immediately and 24 hours after arrest, suggested that differences in resuscitation itself were involved, argued Matthew Tomey, MD, also of Icahn School of Medicine at Mount Sinai, in an accompanying .

"The findings and limitations of this study together sound a call to action," wrote Tomey, an interventional cardiologist and cardiovascular intensivist.

While a high-stakes event, cardiac arrest occurs at a low frequency of about 1% among patients undergoing percutaneous coronary intervention or transcatheter aortic valve replacement.

These cath lab cases account for fewer than 4% of all in-hospital cardiac arrest but aren't comparable to those in other in-hospital settings for a number of reasons, Tomey noted, including "the peculiar environment of the catheterization laboratory, notably including ambient radiation and bulky equipment, complicating both scene safety and the physical execution of cardiopulmonary resuscitation."

In these cases, he wrote, "resuscitation frequently relies on an abundance of expertise with a paucity of protocol. The inherent laxity of this scenario entrusts outcomes of ILCA [in-laboratory cardiac arrest] in large part to the talents, creativity, and fallibility of individuals, in turn exposing risk of variability and disparity in survival."

The study included 4,787 adults from 231 hospitals in the Get With The Guidelines (GWTG)–Resuscitation registry who had an index in-hospital cardiac arrest in the cardiac catheterization laboratory from 2003 through 2017. Models adjusted for demographics, comorbidities, and cardiac arrest characteristics to generate risk-adjusted rates of survival to discharge at each hospital with at least five cases during the study period (the median rate was six cases per hospital annually).

The median adjusted survival for in-laboratory cardiac arrest was 36% overall. Low performing hospitals had more non-white patients, higher rates of comorbidities such as renal and respiratory insufficiency, and a higher prevalence of an initial nonshockable rhythm.

Among the hospital-level factors evaluated, the only significant factor was annual volume of events, with hospitals with higher survival rates having higher yearly volumes of in-laboratory cardiac arrest (P<0.001), without an association with total number of beds, rural versus urban location, teaching status, or geographic location.

Volume of cath lab cardiac arrests could be a surrogate for the cath lab team's experience with cardiac arrest, but it also could reflect procedural volume, the researchers noted. "Higher case volume at the top-performing hospitals may lead to higher quality and more consistent chest compressions, more prompt initiation of acute cardiac life support medications, and greater use of advanced mechanical circulatory support devices. These factors are not captured in GWTG-Resuscitation but may help elucidate the relationship between higher case volume and higher hospital survival rates."

Measures other than survival to hospital discharge showed similar patterns, with immediate post-cardiac arrest survival rates of 53%, 65%, and 76% and 24-hour survival rates of 37%, 53%, and 67%, respectively, across the tertiles from low to high (both P<0.001).

However, Tomey suggested caution "both in interpreting the magnitude of variation suggested by the calculated median OR and in inferring actionable steps to improve survival" due to limitations of the data.

These limitations included lack of data on "type of interventional procedure performed, details of procedural performance, availability and utilization of specific mechanical circulatory support devices including mechanical chest compression devices, and the leadership and execution of resuscitation," he wrote.

"Furthermore, it is presumed, but unknown, that participating hospitals consistently ascertained all ILCA events," he added. "Variability in inclusion of cases, and in particular brief aborted cardiac arrests, could substantially affect measured rates of survival."

The researchers added the limitations of potential for residual confounding, lack of data on resuscitation efforts and postdischarge care, and that the analyses represented only hospitals participating in a voluntary registry.

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