February 1, 1985Open Access
View Full PaperPrognosis after extension of myocardial infarct: the role of Q wave or non-Q wave infarction.
Key Result
Extension of non-Q wave myocardial infarction was associated with significantly higher hospital mortality compared to extension of Q wave infarction (43% vs 15%, p<0.01).
Study Design
Type
Cohort (n=1,253)
Structured PICO
Does extension of myocardial infarct, particularly in non-Q wave vs Q wave infarction, increase early and late mortality in patients with acute myocardial infarction?
P
Population
1253 patients with acute myocardial infarction, including non-Q wave (n=277), Q-anterior (n=462), and Q-inferior (n=497) infarcts.
I
Intervention
Extension of myocardial infarct (diagnosed by recurrent chest pain, new persistent ECG changes, and/or elevation or reappearance of creatine kinase)
C
Comparator
No extension of myocardial infarct, and comparison between Q wave vs non-Q wave infarct extension
O
Outcome
Hospital mortality and 1-year mortalityhard clinical
Extension of a non-Q wave myocardial infarction is associated with a substantially higher hospital mortality rate than extension of a Q wave infarction.
Main Result
Absolute Event Rate: 43% vs 15%
p-value: p=<0.01
Abstract
We examined whether or not subsets of patients with extension of myocardial infarct were at high risk for early and late mortality. Some data suggest increased risk in patients with non-Q wave infarcts and we hypothesized that infarct extension in this group might be associated with a poorer prognosis than that for patients with extension of Q wave infarcts. A total of 1253 patients with acute myocardial infarction who were included in our data base were followed prospectively. The patients were classified according to electrocardiographic results into the following groups: those with non-Q wave (n = 277) infarcts and those with Q-anterior (n = 462) and Q-inferior (n = 497) infarcts. Extension was diagnosed by two of the following criteria: (1) recurrent chest pain 24 hr or more after admission to the hospital, (2) new persistent electrocardiographic changes, and (3) elevation or reappearance of creatine kinase. By these criteria 85 (6%) patients had extension (8% of non-Q wave infarcts, 6% of Q-anterior infarcts, and 6% of Q-inferior infarcts). Hospital mortality in patients with extension was 15% in those with Q wave infarcts vs 43% in those with non-Q wave infarcts (p less than .01). Nine hundred and fifty-two patients were followed for 1 year. In 24% of those who did not survive 1 year there was extension of infarct; only 6% of survivors had extension (p less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)