SPC365

End-tidal carbon dioxide partial pressure – a new prognostic marker after acute myocardial infarction?

Session: Posters - J. Preventive Cardiology
Speaker: Joana Silva Ferreira

Congress: CPC 2021
Topic: J. Preventive Cardiology
Theme: 29. Rehabilitation and Sports Cardiology
Subtheme: 29.1 Exercise Testing
Session Type: Posters
FP Number: ---
Authors: Joana Silva Ferreira; Pedro Rio; Isabel Cardoso; Alexandra Castelo; Sofia Silva; Rui Cruz Ferreira
<p style="text-align:justify"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:14px"><strong><span style="background-color:white"><span style="color:black">Background</span></span></strong><span style="background-color:white"><span style="color:black">: Although several cardiopulmonary exercise testing (CPET) parameters have already proved to predict prognosis, there is increasing interest in finding variables that do not require maximal effort. End-tidal carbon dioxide partial pressure (PETCO2), an indirect indicator of cardiac output, is one of such variables. Studies in heart failure populations already suggest its role as a prognostic factor. However, data concerning other populations are still scarce.</span></span></span></span></p>

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<span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:14px"><span style="color:black"><strong><span style="background-color:white">Purpose</span></strong><span style="background-color:white">: To assess the association between exercise PETCO2, cardiac biomarkers and systolic function following acute myocardial infarction (AMI) and to evaluate its potential prognostic role in this population.</span></span></span></span></p>

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<span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:14px"><span style="color:black"><strong><span style="background-color:white">Methods</span></strong><span style="background-color:white">: A retrospective single-centre analysis was conducted including patients who underwent symptom-limited CPET early after AMI. We assessed PETCO2 at baseline (PETCO2-B), at anaerobic threshold (PETCO2-AT) and at peak exercise and calculated the difference between PETCO2-AT and PETCO2-B (PETCO2-difference). We analysed their association with B-natriuretic peptide (BNP) and maximal troponin after AMI, with other CPET variables, as well as with global longitudinal strain (GLS) and left ventricular ejection fraction (LVEF) 1 year after AMI.</span></span></span></span></p>

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<span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:14px"><span style="color:black"><strong><span style="background-color:white">Results</span></strong><span style="background-color:white">: We included 40 patients with a mean age of 56 years (87.5% male), assessed with CPET a median of 3 months after AMI (80% of which were ST-elevation myocardial infarctions). Average respiratory exchange ratio (RER) was 1.1&nbsp;with 48% of patients not reaching maximal effort (defined as RER </span></span></span><span style="font-size:12pt"><span style="font-size:11.0pt">&ge; 1.1)</span></span><span style="font-size:14px"><span style="color:black"><span style="background-color:white">. Mean PETCO2-AT was 37mmHg, with a mean increase from baseline of 6mmHg (PETCO2-difference). </span></span></span></span></p>

<p style="text-align:justify"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:14px"><span style="background-color:white"><span style="color:black">There was a significant positive correlation between all the PETCO2 variables measured and BNP values at time of AMI and on follow-up (best correlation for PETCO2-AT with BNP at AMI hospitalization: r=0.608, p&lt;0.001). Maximal troponin was not correlated with PETCO2. </span></span></span></span></p>

<p style="text-align:justify"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:14px"><span style="background-color:white"><span style="color:black">Both PETCO2-AT and PETCO2-difference were significantly and negatively correlated with GLS (r= -0.538, p=0.010 and r= -0.629, p=0.002, respectively) and positively correlated with LVEF 1-year post-AMI (r=0.514, p=0.009 and r=0.534, p=0.006, respectively). </span></span></span></span></p>

<p style="text-align:justify"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:14px"><span style="background-color:white"><span style="color:black">Both these variables also showed a significant correlation with peak exercise oxygen uptake (peak VO2) and with the minute ventilation/carbon dioxide production (VE/VCO2) slope (strongest correlation for PETCO2-AT with VE/VCO2 slope: r = -0.857, p&lt;0.001).</span></span></span></span></p>

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<span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:14px"><span style="color:black"><strong><span style="background-color:white">Conclusion</span></strong><span style="background-color:white">: PETCO2-AT and PETCO2-difference are both correlated with medium-term systolic function after AMI. Their correlation with BNP, peak VO2 and VE/VCO2 slope, established prognostic markers, further suggests their potential prognostic role in this population. Further studies with larger samples are required to confirm the results of this pilot study and assess PETCO2 as a definite predictor of prognosis after AMI and a possible surrogate for peak VO2 in submaximal CPET.</span></span></span></span></p>