Sinus bradycardia during hypothermia in comatose survivors of out-of-hospital cardiac arrest: a new early marker of favorable outcome?

TY - JOUR

T1 - Sinus bradycardia during hypothermia in comatose survivors of out-of-hospital cardiac arrest

T2 - a new early marker of favorable outcome?

AU - Thomsen, Jakob Hartvig

AU - Hassager, Christian

AU - Bro-Jeppesen, John

AU - Søholm, Helle

AU - Nielsen, Niklas

AU - Wanscher, Michael

AU - Køber, Lars

AU - Pehrson, Steen

AU - Kjaergaard, Jesper

N1 - Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

PY - 2015/4

Y1 - 2015/4

N2 - Background: Bradycardia is a common finding in patients undergoing therapeutic hypothermia (TH) following out-of-hospital cardiac arrest (OHCA), presumably as a normal physiological response to low body temperature. We hypothesized that a normal physiological response with sinus bradycardia (SB) indicates less neurological damage and therefore would be associated with lower mortality. Methods: We studied 234 consecutive comatose survivors of OHCA with presumed cardiac etiology and shockable primary rhythm, who underwent a full 24-h TH-protocol (33. °C) at a tertiary heart center (years: 2004-2010). Primary endpoint was 180-day mortality; secondary endpoint was favorable neurological outcome (180-day cerebral performance category: 1-2). Results: SB, defined as sinus rhythm <50 beats per minute during TH, was present in 115 (49%) patients. Baseline characteristics including sex, witnessed arrest, bystander cardiopulmonary resuscitation and time to return of spontaneous circulation were not different between SB- and no-SB patients. However, SB-patients were younger, 57. ±. 14 vs. 63. ±. 14 years, p<. 0.001 and less frequently had known heart failure (7% vs. 20%, p<. 0.01).Patients experiencing SB during the hypothermia phase of TH had a 17% 180-day mortality rate compared to 38% in no-SB patients (p<0.001), corresponding to a 180-day hazard ratio (HRadjusted=0.45 (0.23-0.88, p=0.02)) in the multivariable analysis. Similarly, SB during hypothermia was directly associated with lower odds of unfavorable neurological outcome (ORunadjusted=0.42 (0.23-0.75, p<0.01). Conclusion: Sinus bradycardia during therapeutic hypothermia is independently associated with a lower 180-day mortality rate and may thus be a novel, early marker of favorable outcome in comatose survivors of OHCA.

AB - Background: Bradycardia is a common finding in patients undergoing therapeutic hypothermia (TH) following out-of-hospital cardiac arrest (OHCA), presumably as a normal physiological response to low body temperature. We hypothesized that a normal physiological response with sinus bradycardia (SB) indicates less neurological damage and therefore would be associated with lower mortality. Methods: We studied 234 consecutive comatose survivors of OHCA with presumed cardiac etiology and shockable primary rhythm, who underwent a full 24-h TH-protocol (33. °C) at a tertiary heart center (years: 2004-2010). Primary endpoint was 180-day mortality; secondary endpoint was favorable neurological outcome (180-day cerebral performance category: 1-2). Results: SB, defined as sinus rhythm <50 beats per minute during TH, was present in 115 (49%) patients. Baseline characteristics including sex, witnessed arrest, bystander cardiopulmonary resuscitation and time to return of spontaneous circulation were not different between SB- and no-SB patients. However, SB-patients were younger, 57. ±. 14 vs. 63. ±. 14 years, p<. 0.001 and less frequently had known heart failure (7% vs. 20%, p<. 0.01).Patients experiencing SB during the hypothermia phase of TH had a 17% 180-day mortality rate compared to 38% in no-SB patients (p<0.001), corresponding to a 180-day hazard ratio (HRadjusted=0.45 (0.23-0.88, p=0.02)) in the multivariable analysis. Similarly, SB during hypothermia was directly associated with lower odds of unfavorable neurological outcome (ORunadjusted=0.42 (0.23-0.75, p<0.01). Conclusion: Sinus bradycardia during therapeutic hypothermia is independently associated with a lower 180-day mortality rate and may thus be a novel, early marker of favorable outcome in comatose survivors of OHCA.

KW - Adult

KW - Aged

KW - Bradycardia

KW - Coma

KW - Denmark

KW - Female

KW - Humans

KW - Hypothermia, Induced

KW - Male

KW - Middle Aged

KW - Out-of-Hospital Cardiac Arrest

KW - Outcome Assessment (Health Care)

KW - Prevalence

KW - Retrospective Studies

KW - Survival Rate

U2 - 10.1016/j.resuscitation.2014.12.031

DO - 10.1016/j.resuscitation.2014.12.031

M3 - Journal article

C2 - 25619443

SN - 0300-9572

VL - 89

SP - 36

EP - 42

JO - Resuscitation

JF - Resuscitation

ER -