SPC365

Early Oxygen pulse plateau as a prognostic marker in a population of patients with Heart Failure: how soon is too soon?

Session: Comunicações Orais - Sessão 04 - Reabilitação cardíaca
Speaker: Catarina Lagoas Pohle

Congress: CPC 2024
Topic: J. Preventive Cardiology
Theme: 29. Rehabilitation and Sports Cardiology
Subtheme: 29.2 Cardiovascular Rehabilitation
Session Type: Comunicações Orais
FP Number: ---
Authors: Catarina Lagoas Pohle; Rita Almeida Carvalho; Joana Silva Ferreira; Rui Antunes Coelho; Jéni Quintal; Patrícia Bernardes; Anaí Durazzo; Miguel Mendes; Catarina Sá; Filipe Seixo; Gonçalo Lopes da Cunha
<p style="text-align:justify"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><strong>Introduction</strong></span></span></span></p>

<p style="text-align:justify"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">Oxygen pulse (O2P) is a parameter of Cardiopulmonary Exercise Testing (CPET) often used as an indicator of stroke volume. The occurrence of an O2P plateau corresponds to the inability to increase oxygen uptake with an increase in heart rate (Figure 1-A). The subjective observation of an early plateau is a widespread&nbsp;marker of a worse prognosis. However, the exact definition of early plateau is not yet established. </span></span></span></p>

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<p style="text-align:justify"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><strong>Aim</strong></span></span></span></p>

<p style="text-align:justify"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">We aimed to establish the prognostic value of the presence and timing of O2P plateau in a population of patients with Heart Failure (HF).</span></span></span></p>

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<p style="text-align:justify"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><strong>Methods </strong></span></span></span></p>

<p style="text-align:justify"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">A retrospective study was conducted with a sample of HF patients with left ventricular ejection fraction (LVEF) &lt;50% who underwent CPET on a treadmill from 2015-2021. Patients were excluded if they had documented obstructive coronary disease with ischemia. The O2P data was extracted breath by breath and imported to Microsoft Excel. The O2P graph was divided in 4 equal parts and linear regression was fitted to each part to assess the presence of a plateau (defined by a slope less than 0.3 mL/kg/min, according to a previously published work). The primary endpoint was a composite of CV death, HF hospitalization, and urgent heart transplant.</span></span></span></p>

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<p style="text-align:justify"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><strong>Results</strong></span></span></span></p>

<p style="text-align:justify"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">A total of 248 HF patients (66.5% men), with a mean age of 58.3 &plusmn; 11.4 years and a mean LVEF of 34 &plusmn; 9.5%, were included. The average peak oxygen uptake (pVO2) was 18.4 &plusmn; 6.1 mL/min, and the median minute ventilation/carbon dioxide production (VE/VCO2) slope was 38.0 (IQR 32.2 to 46.0).</span></span></span></p>

<p style="text-align:justify"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="font-size:medium">The mean peak O2P value was 12.0&plusmn; 4.0 mL/beat (median of 87.2%, IQR 69.4 to 106.1, of the predicted O2P value). The presence of an O2P plateau was observed in 84.7% (n=210) of patients, occurring before the 1</span></span></span><sup>st</sup><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="font-size:medium">&nbsp;quarter of the test in 8.1% (n=20) of patients, before the 2</span></span></span><sup>nd</sup><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="font-size:medium">&nbsp;quarter in 40.7% (n=101), and before the 3</span></span></span><sup>rd</sup><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="font-size:small">&nbsp;</span><span style="font-size:medium">quarter in 64.9% (n=161). </span></span></span></p>

<p style="text-align:justify"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">While the occurrence of O2P plateau, per se, was not associated with the evaluated endpoints, the timing of the plateau was correlated with prognosis. In fact, O2P plateau before the 1<sup>st</sup>, 2</span></span></span><sup>nd</sup><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">&nbsp; and 3<sup>rd</sup> quarters of CPET was associated with a 4-, 2- and 2- fold increase in the incidence of the primary endpoint, respectively (HR 4.3; 95% CI 2.270 to 8.032, P &lt; 0.001; HR 2.3; 95% CI 1.451 to 3.766, P &lt; 0.001;&nbsp;HR 1.9; 95% CI 1.084 to 3.243, P = 0.025, respectively). (Figure 1-B). </span></span></span></p>

<p style="text-align:justify"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">The occurrence of a plateau before the 3rd quarter adds prognostic value, even when adjusted for pVO2, LVEF, NT-proBNP and&nbsp;VE/VCO2 slope (HR 2.0; 95% CI 1.087 to 3.752, P = 0.026).</span></span></span></p>

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<p style="text-align:justify"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><strong>Conclusion</strong></span></span></span></p>

<p style="text-align:justify"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000">The occurrence of a plateau did not show to have statistically significant prognostic impact in a population of patients with HF. However, the presence of an early O2P plateau (especially in the first three quarters of the test) appears to be associated with a worse CV outcome.</span></span></span></p>