• Interventional Techniques & Devices
• Myocardial Infarction
• Cardiology Clinical Trials

• Interventional Techniques & Devices
• Cardiology & Cardiovascular Medicine
• Myocardial Infarction
• Cardiology Clinical Trials

Niklas Nielsen, MD, PhD, EDIC, DEAA, Helsingborg Hospital, Lund University, Helsingborg, Sweden, presented the final results from the Target Temperature Management After Cardiac Arrest trial [TTM; Nielsen N et al. N Engl J Med 2013], which demonstrated that therapeutic cooling to a lower-temperature target does not improve outcomes of unconscious survivors of out-of-hospital cardiac arrest (OHCA) compared with cooling to standard temperature targets.

OHCA carries a high risk of death and poor neurological outcomes. Since induced hypothermia is associated with improved outcomes in these patients, its use is recommended in clinical guidelines. However, the optimal target temperature is unknown [Nielsen N et al. Int J Cardiol 2011].

The TTM trial [Nielsen N et al. N Engl J Med 2013] is the largest trial to study hypothermia in cardiac arrest patients. This international, multicenter, randomized trial was designed to evaluate whether cooling to a target temperature of 33°C compared with 36°C improved outcome in patients with OHCA.

Inclusion criteria were OHCA, age ≥18 years, unconscious, presumed cardiac cause, and stable return of spontaneous circulation (ROSC).

Exclusion criteria included unwitnessed cardiac arrest with initial rhythm of asystole, ROSC to screening interval >240 minutes, known or suspected acute intracranial hemorrhage or stroke, and body temperature <30°C.

The primary endpoint of the study was all-cause mortality through the end of the trial, and the main secondary outcome was a composite of death or poor neurologic function at 180 days, as evaluated by the Cerebral Performance Category scale and modified Rankin scale.

A total of 939 OHCA patients were enrolled in the study and randomized 1:1 to either target temperature managements of 33°C (n=473) or 36°C (n=466) for 24 hours.

At the end of the trial, there was no significant difference in the primary endpoint of patient mortality between the 33°C and 36°C groups (50% vs 48%; p=0.51).

And similarly, at 180-day follow-up, there was no significant difference in the percentage of patients who had died or had poor neurologic function, as evaluated with either the Cerebral Performance Category scale (54% vs 52%; p=0.78), or the modified Rankin scale (both 52%; p=0.87).

Serious adverse events, including bleeding, pneumonia, and electrolyte disturbances, were frequent in both the 33°C group and the 36°C group (93% vs 90%; p=0.09), with a significant increase in the incidence of hypokalemia (19% vs 13%; p=0.02)

Prof. Nielsen concluded that these results do not suggest any benefit for a target body temperature of 33°C in unconscious OHCA patients compared with 36°C. The optimal temperature for therapeutic hypothermia in this patient population therefore remains unclear, and further study is needed to determine the optimal temperature goal for patients with OHCA being treated with therapeutic hypothermia.

• © 2013 MD Conference Express®