Prognostic value of impaired spirometry in patients with myocardial infarction: a longitudinal study of two European cohorts

PURPOSE: The study aimed to investigate the associations between impaired spirometry such as obstructive pattern and preserved ratio impaired spirometry (PRISm) and occurrent cardiovascular events and deaths in patients with acute myocardial infarction.

PATIENTS AND METHODS: Cohort study of 517 patients with age ≥40 years and ≥10 pack-years of smoking, hospitalized for myocardial infarction at eight sites in Sweden and the United Kingdom. The Vitalograph® COPD-6 device was used to assess the ratio of forced expiratory volume in 1 and 6 seconds (FEV1/FEV6) and FEV1 as a percentage of the predicted value (FEV1%pred). Obstructive pattern was defined as FEV1/FEV6 <0.7, PRISm as FEV1/FEV6 >0.7 and FEV1%pred <80, and normal findings as FEV1/FEV6 ≥0.7 and FEV1%pred ≥80. Follow-up data were obtained from national registers or follow-up visits. Multivariable Cox regression was used to analyze the associations of obstructive pattern and PRISm with the incidence of acute ischemic cardiovascular events or major adverse cardiovascular events (MACE), respectively, within one year.

RESULTS: Obstructive pattern was found in 95 (18%), PRISm in 192 (37%) and normal spirometry in 230 (45%) patients. A cardiovascular event occurred in 21 (4%) and MACE in 28 (5%). Compared with normal spirometry, PRISm was independently associated with both new cardiovascular events (HR (95% CI) 3.44 (1.07-11.0)) and MACE (4.94 (1.63 to 15.0)), and obstructive pattern with MACE (3.87 (1.08-13.8)). Further adjustment for cardiac or COPD treatment did not substantially change the results.

CONCLUSION: About half of patients with acute myocardial infarction and a ≥10 pack-year smoking history have abnormal spirometry findings. Both obstructive pattern and PRISm are independently associated with increased risk for MACE within one year. We suggest that spirometry should be considered as a routine assessment in patients with smoking history and recent myocardial infarction.