Of patients who were hospitalized and treated for moderate to severe carbon monoxide poisoning, those who sustained heart muscle injury due to their exposure had an increased risk of death during a mid-point follow-up period of 7.6 years compared to those without injury to the heart.

Despite a decline in the annual death rate from carbon monoxide ( CO ) poisoning, CO remains the most common type of accidental poisoning in the United Sates, contributing to 40,000 emergency department visits each year.

The Centers for Disease Control and Prevention ( CDC ) reported that from 1968 through 1998 carbon monoxide poisoning contributed to an average of 1,091 unintentional deaths and 2,385 suicidal deaths in the U.S. annually.
Symptoms of CO poisoning include weakness, nausea, dizziness, lethargy, confusion and headache. In addition to neurological effects, heart damage has also often been reported in carbon monoxide poisoning cases.

Christopher R. Henry, of the Minneapolis Heart Institute Foundation, and colleagues studied 230 patients treated for moderate to severe carbon monoxide poisoning to evaluate the association between the patients' heart damage following carbon monoxide poisoning and long-term risk of death.

Patients admitted to the Hennepin County Medical Center between January 1, 1994, and January 1, 2002, were included in the study, with follow-up conducted through November 11, 2005.
Heart muscle damage was characterized by elevated levels of cardiac troponin I or creatine kinase-MB, and/or changes in diagnostic electrocardiogram ( ECG ).

Heart muscle injury occurred in 85 ( 37 percent ) of the 230 patients with carbon monoxide poisoning. At a mid-point follow-up of 7.6 years ( ranging up to 11.8 years ), 54 deaths had occurred ( 24 percent ), with 12 ( 5 percent ) of those deaths taking place in the hospital.

Of the 85 patients with heart damage, 32 ( 38 percent ) died during follow-up compared with 22 ( 15 percent ) of 145 patients without damage to the heart.
Of those patients with a heart injury who died, 44 percent ( 14 ) died of presumed cardiovascular causes ( i.e., cardiac arrest, myocardial infarction ).

" Patients with suspected exposure to carbon monoxide should be screened for myocardial injury, and further cardiovascular risk stratification should be considered in all patients with confirmed myocardial injury, " the researchers report. " Our data indicate these patients have poor long-term outcome, a topic that deserves further study."

Source: American Medical Association, 2006


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