Background: An isolated posterior myocardial infarction (PMI) is associated with significant morbidity and mortality. Because physicians often fail to recognize this diagnosis, there may be delays in the timely revascularization of these patients. The present study sought to identify the clinical characteristics and reperfusion times among patients presenting with isolated PMI.
Methods: We identified subjects with isolated PMI within a registry of all catheterization laboratory activations for ST-elevation myocardial infarction (STEMI) from 2008 to 2012. Association between PMI and revascularization within 90 minutes was evaluated by logistic regression.
Results: Among 318 patients who underwent revascularization for STEMI, a total of 20 (6%) had electrocardiographic evidence of an isolated PMI. Compared to non-PMI STEMI, subjects with PMI were more often female (45% vs 22%; P=.02) and less likely to have chest pain (40% vs 75%; P<.01). The median door-to-activation (25.5 min vs 12 min; P<.01), activation-to-laboratory (36.5 min vs 29 min; P<.01) and door-to-balloon times (107 min vs 72 min; P<.01) were longer among subjects with PMI, with fewer patients achieving reperfusion within 90 minutes (30% vs 71%; P<.01). After multivariable adjustment, individuals with PMI had 82% lower odds (adjusted odds ratio, 0.18; 95% confidence interval, 0.06-0.50) of achieving coronary reperfusion within 90 minutes. Door-to-activation time accounted for 96% of variation in the total revascularization time (R²=0.96; P<.0001).
Conclusions: Door-to-activation time was prolonged for those with PMI, resulting in longer door-to-balloon times and fewer patients revascularized within the recommended time. An isolated PMI should be considered among individuals presenting with symptoms consistent with myocardial infarction.