CO Gap Alone Is Not a Prognostic Marker for 28-Day Survival of Patients Undergoing a Transcatheter Aortic Valve Replacement.

The venous-to-arterial difference in partial pressure of carbon dioxide (CO gap) has been suggested as a marker of cardiac output and clinical outcomes. This study aimed to evaluate the CO gap as a prognostic indicator for 28-day survival in patients undergoing transcatheter aortic valve replacement (TAVR) and to explore its relationship with cardiac function and lactate levels. In this prospective cohort study, 50 TAVR patients were stratified based on their left ventricular ejection fraction (LV-EF) and survival status. Central venous and arterial blood samples were collected at five time points to measure blood gas parameters. The primary endpoint was the prognostic value of the CO gap for 28-day survival. Secondary endpoints included group differences in the CO gap, its correlation with lactate levels, and CO content analysis. ROC analysis indicated limited prognostic value for 28-day survival. The CO gap was higher in non-survivors than in survivors (11.1 mmHg vs. 6.8 mmHg, = 0.039), but showed no significant difference between individual time points. The CO gap between cardiac (LV-EF ≤ 50%) and non-cardiac (LV-EF > 50%) groups showed no significant difference. Lactate and CO gap showed no correlation, except at T2 in the cardiac group ( = 0.039, r = 0.525). CO content showed no significance, except at T5, where it was significantly higher in survivors (5.3 mL/dL vs. 1.1 mL/dL, = 0.003). The CO gap did not emerge as a reliable prognostic marker for 28-day survival in TAVR patients. Further studies are needed to explore its clinical relevance.