Myocardial Infarction Without Chest Pain
September 1, 2000
Myocardial Infarction Without Chest Pain
ABSTRACT & COMMENTARY
Source: Canto JG, et al. Clinical characteristics and mortality among patients with myocardial infarction presenting without chest pain. JAMA 2000;283:3223-3229.
The objective of this prospective observational study was to determine the frequency with which patients with myocardial infarction (MI) present without chest pain and to examine their clinical characteristics, subsequent management, and mortality compared to those with chest pain. The data were collected as part of the National Registry of Myocardial Infarction 2, which included a total of 434,877 patients with confirmed MI from 1674 hospitals in the United States. Chest pain was defined as any symptom of chest discomfort (including pressure) or arm, neck, or jaw pain.
Of all patients diagnosed with MI, 33% did not have chest pain on presentation to the hospital. MI patients without chest pain were older than those with chest pain (74.2 vs 66.9 years), with a higher proportion of women (49.0% vs 38.0%) and patients with diabetes mellitus (32.6% vs 25.4%) or prior heart failure (26.4% vs 12.3%). All of these differences were statistically significant.
Patients experiencing MI without chest pain were more likely to have a longer delay before hospital presentation (mean 7.9 vs 5.3 hours) and were less likely to be admitted with an initial diagnosis of MI (22.2% vs 50.3%). In addition, MI patients without chest pain were less likely to be treated with thrombolysis or primary angioplasty (25.3% vs 74.0%) and were less likely to receive aspirin, ß-blockers, or heparin. All of these differences were, again, statistically significant. The MI patients without chest pain had a 23.3% in-hospital mortality rate compared to 9.3% in patients with chest pain (adjusted odds ratio for mortality, 2.21 [95%, CI 2.17-2.26]).
Comment by Stephanie B. Abbuhl, MD, FACEP
This study is a wake-up call to remind us that MI patients without chest pain are common and that we must be careful not to withhold standard treatments and to pay attention to the timeliness of diagnosis and therapy in this important group. The number of MI patients without chest pain was a remarkable proportion (one-third), and should remind us of the need to have a low threshold for considering the diagnosis of MI in patients with other complaints. Unfortunately, this study did not collect data about the exact nature of the other presenting complaints. Until the spectrum of other common presentations is defined, public health initiatives will need to emphasize a broader range of symptoms than only chest pain.
It was interesting to note that only one-third of the MI patients without chest pain were diabetics, challenging the common teaching that diabetes alone is the chief risk factor for MI without chest pain. MI patients without chest pain had greater than twice the in-hospital mortality than MI patients with chest pain. This finding is somewhat surprising and was true even after adjusting for differences in age, co-morbidities, and severity of presentation. Only 28% of the higher mortality could be attributed to the lower use of early standard treatments. This study, along with many others, again has demonstrated the lack of concordance between actual ischemia/infarction and the symptom of chest pain, and points to our difficulty in diagnosing and treating an illness that has many faces and can even, at times, be silent.
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