Atypical MI Symptoms Tied to Higher Mortality, Poorer Emergency Response

By Marilynn Larkin

May 14, 2021

NEW YORK (Reuters Health) - Patients having a myocardial infarction (MI) with atypical symptoms had less chance of receiving an emergency dispatch when they called for help, and higher 30-day mortality, compared to those presenting with chest pain, an observational study in Denmark found.

The study involved residents of Copenhagen, which has both an emergency phone number (1-1-2; equivalent to 9-1-1) and a 24-hour non-emergency medical helpline. Both services register symptoms and the purpose of calls.

Among patients with MI as either a hospital diagnosis or cause of death within 72 hours after a call, the primary symptom was recorded either as chest pain, atypical symptoms (e.g., breathing problems, unclear problem, central nervous system symptoms, abdominal/back/urinary, other cardiac symptoms), unconsciousness, non-informative symptoms, or no recorded symptoms.

"I was surprised to find that 24% of the MI patients with information on symptoms had atypical symptoms and additionally, that approximately 40% of all MI patients had called the non-emergency medical service," lead author Amalie Lykkemark Møller of Nordsjaellands Hospital in Hillerod Denmark told Reuters Health by email. "I would have expected that a larger proportion of patients would have been aware of having a serious, urgent condition and instead called the emergency medical service."

As reported in European Heart Journal - Acute Cardiovascular Care, 4,880 emergency and 3,456 helpline calls were received from MI patients between 2014-2018.

Chest pain was the most common symptom, followed by breathing problems. The prevalence of chest pain was highest among men ages 30-59 calling the emergency number (85%), and lowest among women older than 79 calling the medical helpline (49%). Atypical symptoms were found mainly among the elderly, especially women, at the medical helpline.

The proportion of MI patients receiving emergency dispatch was highest for those with unconsciousness (96%-100%), followed by chest pain (82%-91%). Emergency dispatches were rare for other cardiac symptoms (0-31%), other atypical symptoms (5%-32%), and abdominal/back/urinary symptoms (5%-36%).

Among patients with chest pain, 95% of emergency calls and 76% of calls to the medical helpline received emergency dispatch. Among patients with atypical symptoms, emergency dispatch was activated for 62% of emergency calls and for 17% of helpline calls.

Thirty-day mortality was 5% for MI patients who made emergency calls and 3% for those who placed helpline calls. Among MI patients with atypical symptoms, however, 30-day mortality averaged 23% after calls to the emergency number and 15% after calls to the medical helpline.

"Although our research cannot directly be used to advise changes to emergency protocols, I hope it will raise awareness that atypical presentations are relatively common among MI patients, and especially among the elderly, women and patients calling non-emergency medical services," Møller said.

Dr. Nathaniel Smilowitz, an interventional cardiologist and assistant professor of medicine at NYU Langone Health in New York City, commented on the study in an email to Reuters Health. "Although the challenges associated with patients who do not develop chest pain during MI are well known to cardiovascular specialists, this study provides important data to contextualize the problem."

"Although demographics in Denmark and the provision of medical care differs from the US, I would expect similar associations between atypical symptoms at presentation, delays in care, and adverse outcomes in the US as well," he said.

"With advances in remote monitoring devices such as mobile electrocardiography," he added, "home-based health technology may someday be used to assist in the triage of patients calling with symptoms potentially due to MI."

SOURCE: European Heart Journal - Acute Cardiovascular Care, online May 5, 2021.