Patients presenting with atypical symptoms of myocardial infarction (MI) when calling for help are less likely to receive an emergency dispatch and have increased mortality, according to a study published online May 5 in the European Heart Journal: Acute Cardiovascular Care.

Amalie Lykkemark M?ller, from Nordsj?llands Hospital in Hiller?d, Denmark, and colleagues examined the correlations between symptom presentation and chance of receiving an emergency dispatch and 30-day mortality among patients with acute MI. A total of 4,880 emergency and 3,456 nonemergency calls from patients with MI were identified. The primary symptom was categorized as chest pain, atypical symptoms, unconsciousness, noninformative symptoms, and no recorded symptoms.

The researchers found that the most common symptoms were chest pain and breathing problems (5,219 and 556 patients, respectively). Among patients with chest pain, 95 and 76 percent of emergency calls and nonemergency calls, respectively, received emergency dispatch, and mortality was 5 and 3 percent, respectively. For atypical symptoms, the corresponding percentages receiving emergency dispatch were 62 and 17 percent, while the corresponding mortality was 23 and 15 percent. Among unconscious patients, 99 and 100 percent, respectively, received emergency dispatch, and mortality was 71 and 75 percent, respectively. For chest pain and atypical symptoms, standardized 30-day mortality was 4.3 and 15.6 percent, respectively.

"We found that patients with MI presenting with atypical symptoms when calling for help had a lower chance of receiving an emergency dispatch compared to MI patients with chest pain, especially when calling a nonemergency medical service," the authors write.

Several authors disclosed financial ties to the pharmaceutical industry.