Chest Pain Severity Not a Telltale Sign for MI

Marlene Busko

August 18, 2011

July 29, 2011 (Philadelphia, Pennsylvania) — Among patients presenting to an emergency room (ER) with potential acute coronary syndrome (ACS), those with severe chest pain were not more likely to have an acute MI or 30-day cardiovascular complications than those whose pain was less intense, in a new study published online July 26, 2011 in the Annals of Emergency Medicine [1].

Although it is important to relieve pain to make the patient comfortable, "pain severity itself should not be a factor in evaluating patients' risk for acute coronary syndrome in terms of discharge decisions," the authors write. Patient "history, physical, and classic cardiovascular risk factors . . . make more of a difference than something as subjective as pain score," corresponding author Dr Anna Marie Chang (Hospital of the University of Pennsylvania, Philadelphia) told heartwire .

"The take-home message for all care providers is that in the area of chest pain that might be evolving ACS, do not discount or be less aggressive in your evaluation and clinical management of the patient if their pain is described as less than severe," American College of Emergency Room Physicians (ACEP) spokesperson Dr Harry W Severance (University of Tennessee Health Science Center, Memphis) concurred, in a comment to heartwire .

Must Severe Pain Be Present in Impending MI?

Failing to diagnose MI accounts for 20% of malpractice dollars lost among emergency-room physicians, and lawyers and laypeople often believe that the more severe the chest pain is, the more likely that the person is having a heart attack, the authors write.

Hypothesizing that pain severity was not linked to risk of acute MI or 30-day cardiovascular complications, the group performed a secondary analysis of data from a prospective cohort of patients presenting to the emergency room with possible ACS. The primary outcome was prevalence of acute MI, and the secondary outcome was a composite of death, acute MI, and PCI or CABG at 30 days.

At triage, study patients rated their pain from 0, or "no pain," to 10, or "worst pain imaginable." Patients who rated their pain as 0--possibly because they were not currently in pain--were excluded.

The study included 1429 men and 1875 women with a mean age of 51+12.6 years who were black (66%), white (27%), or another race (4%). Follow-up information was available for 93% of the patients.

By 30 days, 111 patients (3.2%) had an acute MI, 34 patients had died, and 105 patients had undergone revascularization.

Events and Relative Risk Stratified by Pain Score

Pain score

1–8 (n=2708), n (%)

9–10 (n=598), n (%)

Relative risk (95% CI)b

Acute MI during initial hospitalization

82 (3.0)

23 (3.9)

1.28 (0.93–1.76)

30-day composite outcomea

135 (5.0)

36 (6.0)

1.19 (0.91–1.56)

a. Death, acute MI, PCI, or CABG

b. Relative risk in severe pain group

Severe pain--a score of 9 or 10--did not increase the risk of acute MI or 30-day composite cardiovascular outcome. After adjustment for age, sex, race, cardiac risk factors, medical history, TIMI score, pain duration, and mode of arrival at the ER, acute MI was related to TIMI score, male sex, and arrival by emergency medical services, but not to age, white race, pain duration more than one hour, or severe pain.

Pain Is Subjective and Complex

"We still do not totally understand the negative feedback systems for coronary chest pain that seem to reduce coronary pain appreciation in some groups of patients," Severance said. "Beyond that, there is simply an individual variance in how patients perceive and even describe pain, including social, cultural, and gender differences."

The findings are consistent with what is known about ACS--that it may or may not have classic symptoms because of the way the heart is innervated, ACEP spokesperson Dr Louis Graff (Hospital of Central Connecticut, New Britain) said in a comment to heartwire . "The brain often interprets signals from the heart as pain in places other than the chest (jaw, arm, back) or as another type of problem or effect of the damaged heart muscle not working normally (can't breathe, weak, etc)."

More than half of patients with acute MI present with "chest-pain equivalents" of shortness of breath, rapid heart rate, syncope, or unexplained weakness, he added, noting that these patients have a higher mortality.

While pain severity may not be a good signal, it is still important for people with suspected heart attack to react quickly. "As many as one-third of heart attacks may go unrecognized by patients, so people with chest pain should still get to the emergency department as quickly as possible to be evaluated," Chang cautioned.

The authors had no disclosures.

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