Abstract 77: Tachycardia During Hypothermia as a Marker of Poor Outcomes in Cardiac Arrest Survivors
Hypothesis: Therapeutic hypothermia in cardiac arrest survivors is typically associated with bradycardia. We investigated clinical and demographic variables and outcomes associated with tachycardia in patients treated with therapeutic hypothermia.
Methods: Demographic and clinical data, and ECGs of 26 consecutive cardiac arrest survivors (9 females, 58+/-18 years old, 5 with history diabetes, and 6 with history of coronary artery disease) on admission, during and after therapeutic hypothermia were reviewed. Analyses of variance, chi-square, and logistic regression were used. The study was approved by the IRB.
Results: Tachycardia (heart rate > 100 bpm, 81% sinus, no VT-VFib) was observed in 40% of ECG tracings before or during hypothermia or after re-warming. Tachycardia was more common in females (55 vs. 32%, p=0.044), patients with pulmonary disease (39 vs. 13%, p=0.009), or when pre-resuscitation rhythm was PEA (60 vs. 27%, p=0.003) or asystole (23 vs. 15%, p=0.003). Diabetes, myocardial ischemia, LV systolic dysfunction, acute infection, renal insufficiency, treatment with ACE inhibitors or diuretics were not associated with tachycardia. There were multiple biochemical abnormalities associated with tachycardia, including decreased pH (p<0.0001) and decreased hemoglobin (p=0.028), increased glucose (p<0.001), sodium (p=0.078), potassium (p=0.044), or creatinine (p=0.108).
Tachycardia was associated with significantly increased hospital mortality (53% vs. 28%, p=0.029), regardless whether it was observed on admission (63 vs. 38%), during hypothermia (67% vs. 33%), or after the re-warming (67 vs. 33%). In multivariate logistic regression analysis only cardiac arrest rhythm (HR of death with PEA-Asystole 11.1, 95%CI 3.2-38.4, p<0.001), but not demographic or biochemical variables or tachycardia (HR 1.7, 95%CI 0.5-5.8, p=0.391) were predictive of mortality.
Conclusion: Tachycardia in cardiac arrest survivors undergoing therapeutic hypothermia is a marker of poor prognosis, likely reflective of severe metabolic abnormalities, especially in patients presenting with pulseless electrical activity or asystole. More studies of this important subject are needed.
- © 2012 by American Heart Association, Inc.