Pulmonary infarction secondary to pulmonary embolism: An evolving paradigm

BACKGROUND AND OBJECTIVE: Pulmonary infarction (PI) from pulmonary embolism (PE) remains an entity of unclear aetiology. PI has been thought to occur in elderly patients with cardiopulmonary disease. We hypothesize younger patients without cardiopulmonary comorbidities are at highest risk. Our study aims to characterize PI clinically and radiographically, determine associated risk factors and determine their clinical significance. METHODS: We conducted a single-centre retrospective review of 367 consecutive patients with PE. Clinical and radiographic data were compared between patients with and without PI using chi-square and F-tests. Univariate and multivariate analyses were performed to evaluate risk factors for PI. RESULTS: PI occurred in 62 of 367 patients with acute PE (16.9%). Patients with PI were significantly younger (48 ± 20.3 vs 59.6 ± 17.2 years, P < 0.01), with lower pulmonary embolism severity index (PESI) scores (73.7 ± 38.1 vs 91.9 ± 37.5 years, P < 0.01) and endorsed chest pain with significantly higher frequency (65% vs 39%, P < 0.01). There was no significant difference in other clinical symptoms, hospital length of stay or mortality between groups. Presence of radiographic cardiopulmonary disease was significantly lower in patients with PI (emphysema: 5% vs 22%, P = <0.01; aortic atherosclerosis: 23% vs 43%, P = <0.01). In multivariate analysis, age ≤33 (OR 3.5 CI: 1.37-8.95, P < 0.01), chest pain (OR 2.15 CI: 1.15-4.00, P = 0.02) and pleural effusion (OR 2.18 CI: 1.08-4.41, P = 0.03) increased PI risk and presence of emphysema decreased risk (OR 0.21 CI: 0.06-0.70, P = 0.01). CONCLUSION: Younger patients without cardiopulmonary comorbidities are at highest risk of PI. Chest pain and pleural effusion significantly increased risk of PI while presence of radiographic emphysema reduced risk.