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. 2025 Oct 7:zwaf559.
doi: 10.1093/eurjpc/zwaf559. Online ahead of print.

The prognostic value of expiratory carbon monoxide level for outcome prediction after myocardial infarction

Antoine Léquipar  1   2   3 , Manveer Singh  1   2   3 , Jean Guillaume Dillinger  1   2   3 , Antonin Trimaille  4 , Claire Bouleti  5 , Clément Delmas  6   7 , Guillaume Schurtz  8 , Sonia Houssany-Pissot  9 , Reza Rossanaly Vasram  10 , Edouard Gerbaud  11 , Damien Millischer  12 , Amine El Ouahidi  13 , Nabil Bouali  5   14 , Emmanuel Gall  1   2   3 , Christophe Thuaire  15 , François Roubille  16 , Nathalie Noirclerc  17 , Stéphane Andrieu  18 , Charles Fauvel  19 , Alexandre Lafont  1   2   3 , Sebastian Voicu  1   20 , Nathan El Bèze  1   2   3 , Charly Alizadeh  3 , Paul Guiraud-Chaumeil  1   2   3 , Jeremy Florence  1   2   3 , Solenn Toupin  1   2   3 , Victor Aboyans  21 , Eric Vicaut  2   3   22 , Théo Pezel  1   2   3 , Patrick Henry  1   2   3
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The prognostic value of expiratory carbon monoxide level for outcome prediction after myocardial infarction

Antoine Léquipar et al. Eur J Prev Cardiol. .

Abstract

Aims: To assess the prognostic value of expiratory carbon monoxide (CO) levels in patients admitted for myocardial infarction (MI).

Methods and results: In this prospective study, expiratory CO levels were measured upon admission in consecutive patients hospitalized for MI across 39 centres. The primary outcome was 1-year all-cause death. Secondary outcomes included 1-year major adverse cardiac events (MACEs: cardiovascular death and recurrent MI) and in-hospital major adverse events (MAEs: death, severe ventricular arrhythmia, cardiogenic shock, and the need for mechanical ventilation). The prognostic value of expiratory CO levels was further evaluated using machine learning (ML) analysis. Among 717 patients (64 ± 13 years; 75% males; 33% active smokers; 43% ST-elevation MI), elevated expiratory CO levels (>11 ppm) were found in 79 patients (11%). Patients with elevated CO levels had a higher rate of 1-year all-cause mortality compared with those without (16.5% vs. 5.2%, P < 0.001). Elevated CO levels were independently associated with 1-year all-cause death across various adjustment models: comorbidities [odds ratio (95% confidence interval): 3.6 (1.7-7.5)], clinical parameters of in-hospital severity [4.5 (2.3-8.8)], and respiratory parameters [6.3 (3.1-12.8)]. Elevated CO levels were also independently associated with a significant increase in 1-year MACEs and in-hospital MAEs. Machine learning analysis identified CO level as one of the most important predictors of adverse events, compared with other known prognosticators.

Conclusion: This is the first study to demonstrate that elevated expiratory CO levels upon admission are independently associated with an increased risk of 1-year all-cause mortality, 1-year MACEs, and in-hospital MAEs in patients hospitalized for MI.

Keywords: Carbon Monoxide; Machine Learning; Myocardial Infarction; Preventive Cardiology; Prognosis; Smoking.

Plain language summary

Carbon monoxide (CO) is produced by the combustion of carbon containing compounds such as cigarette or air pollution. Once inhaled, CO is rapidly absorbed into the bloodstream, significantly reducing the blood's oxygen-carrying capacity. This oxygen deprivation may worsen myocardial infarction (MI). We aimed to evaluate the prognostic value of expiratory CO levels upon admission in patients hospitalized for MI.Among 717 patients, elevated CO level was independently associated with a significant increase in 1-year all-cause mortality, 1-year major adverse cardiac events, and in-hospital major adverse events.Machine learning analysis identified expiratory CO levels as one of the most important predictors of adverse events compared to other known prognosticators.

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Conflict of interest statement

Conflict of interest: No authors report any conflicts of interest. Authors had full access to all the data in the study and accept responsibility to submit for publication.

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