Left Ventricular Morphology and Function as a Determinant of Pulmonary Hypertension in Patients with Severe Aortic Stenosis: Cardiovascular Magnetic Resonance Imaging Study

Main pulmonary artery diameter in combination with cardiovascular biomarkers: new possibilities to identify pulmonary hypertension in patients with severe aortic valve stenosis

BACKGROUND

Echocardiography is currently the noninvasive method of choice to screen patients with severe aortic valve stenosis (AS) for pulmonary hypertension (PH) by estimating systolic pulmonary artery pressure (sPAP). However, radiological options are also available by determining the main pulmonary artery (MPA) diameter in the setting of CT angiography. The aim of the present study was to compare cardiovascular biomarkers with the MPA diameter to allow other ways of detecting PH in patients with severe AS.

METHODS

One hundred ninety-four patients with severe AS undergoing transcatheter aortic valve replacement (TAVR) were included in this study and were divided into two groups based on the CT-angiographically determined MPA diameter. In accordance with ESC guidelines, a cut-off value of 29 mm was determined in this study, with the absence of PH defined by an MPA diameter <29 mm (N79/194) and the presence of PH defined by an MPA diameter ≥29 mm (115/194). Immediately before interventional aortic valve replacement, blood samples were drawn from the subjects and relevant cardiovascular biomarkers such as BNP, cTnI, GDF-15, H-FABP, IGF-BP2 and suPAR were assessed.

RESULTS

Patients with an MPA diameter ≥29 mm had significantly higher BNP (P=0.004), cTnI (P=0.039) and H-FABP (P=0.015) plasma levels, whereas GDF-15 (P=0.140), IGF-BP2 (P=0.088) and suPAR (P=0.140) showed no significant differences. In addition, cut-off values were calculated to predict an MPA diameter ≥29 mm. Significant results were shown with 1634.00 pg/mL for BNP (P=0.004), with 16.50 pg/mL for cTnI (P=0.039) and with 1.16 ng/mL for H-FABP (P=0.016). In a combined biomarker analysis, the 2-way combination of BNP and IGF-BP2 (AUC 0.671; 95%CI 0.538-0.805; P=0.023) and the 3-way combination of BNP, H-FABP and IGF-BP2 (AUC 0.685; 95%CI 0.551-0.818; P=0.015) showed the best results. Biomarker follow-up at 3 and 12 months after TAVR did not require additional information gain. Regarding 1-year survival, no significant difference could be detected between patients with an MPA diameter<29 mm compared to patients with ≥29 mm (log-rank test: P=0.262).

CONCLUSIONS

The MPA diameter remains a controversial parameter for the detection of PH in patients with severe AS. Standing on its own, this non-invasive parameter may not be precise enough to detect PH accurately. Combining this parameter with several biomarkers did not provide significant additional information.

A Story of PA/BSA and Biomarkers to Diagnose Pulmonary Hypertension in Patients with Severe Aortic Valve Stenosis-The Rise of IGF-BP2 and GDF-15

(1) Background: Currently, echocardiography is the primary non-invasive diagnostic method used to screen patients with severe aortic valve stenosis (AS) for pulmonary hypertension (PH) by estimating systolic pulmonary artery pressure (sPAP). Other radiological methods have been a focus of research in the past couple of years, as it was shown that by determining the pulmonary artery (PA) diameter, prognostic statements concerning overall mortality could be made in these patients. This study compared established and novel cardiovascular biomarkers with the PA/BSA value to detect PH in patients with severe AS. (2) Methods: The study cohort comprised 188 patients with severe AS undergoing transcatheter aortic valve replacement (TAVR), who were then divided into two groups based on PA/BSA values obtained through CT-angiography. The presence of PH was defined as a PA/BSA ≥ 16.6 mm/m2 (n = 81), and absence as a PA/BSA < 16.6 mm/m2 (n = 107). Blood samples were taken before TAVR to assess cardiovascular biomarkers used in this study, namely brain natriuretic peptide (BNP), cardiac troponin I (cTnI), high-sensitive troponin (hsTN), soluble suppression of tumorigenesis-2 (sST2), growth/differentiation factor 15 (GDF-15), heart-type fatty acid-binding protein (H-FABP), insulin-like growth factor binding protein 2 (IGF-BP2), and soluble urokinase-type plasminogen activator receptor (suPAR). (3) Results: Patients with a PA/BSA ≥ 16.6 mm/m2 showed significantly higher levels of BNP (p = <0.001), GDF-15 (p = 0.040), and H-FABP (p = 0.007). The other investigated cardiovascular biomarkers did not significantly differ between the two groups. To predict a PA/BSA ≥ 16.6 mm/m2, cut-off values for the biomarkers were calculated. Here, GDF-15 (p = 0.029; cut-off 1172.0 pg/mL) and BNP (p < 0.001; cut-off 2194.0 pg/mL) showed significant results. Consequently, analyses of combined biomarkers were performed, which yielded IGF-BP2 + BNP (AUC = 0.721; 95%CI = 0.585−0.857; p = 0.004) as the best result of the two-way analyses and GDF-15 + IGF-BP2 + BNP (AUC = 0.727; 95%CI = 0.590−0.864; p = 0.004) as the best result of the three-way analyses. No significant difference regarding the 1-year survival between patients with PA/BSA < 16.6 mm/m2 and patients with PA/BSA ≥ 16.6 mm/m2 was found (log-rank test: p = 0.452). (4) Conclusions: Although PA/BSA aims to reduce the bias of the PA value caused by different body compositions and sizes, it is still a controversial parameter for diagnosing PH. Combining the parameter with different cardiovascular biomarkers did not lead to a significant increase in the diagnostic precision for detecting PH in patients with severe AS.

Severe Aortic Valve Stenosis and Pulmonary Hypertension: A Systematic Review of Non-Invasive Ways of Risk Stratification, Especially in Patients Undergoing Transcatheter Aortic Valve Replacement

Patients with severe aortic valve stenosis and concomitant pulmonary hypertension show a significantly reduced survival prognosis. Right heart catheterization as a preoperative diagnostic tool to determine pulmonary hypertension has been largely abandoned in recent years in favor of echocardiographic criteria. Clinically, determination of echocardiographically estimated systolic pulmonary artery pressure falls far short of invasive right heart catheterization data in terms of accuracy. The aim of the present systematic review was to highlight noninvasive possibilities for the detection of pulmonary hypertension in patients with severe aortic valve stenosis, with a special focus on cardiovascular biomarkers. A total of 525 publications regarding echocardiography, cardiovascular imaging and biomarkers related to severe aortic valve stenosis and pulmonary hypertension were analyzed in a systematic database analysis using PubMed Central®. Finally, 39 publications were included in the following review. It was shown that the current scientific data situation, especially regarding cardiovascular biomarkers as non-invasive diagnostic tools for the determination of pulmonary hypertension in severe aortic valve stenosis patients, is poor. Thus, there is a great scientific potential to combine different biomarkers (biomarker scores) in a non-invasive way to determine the presence or absence of PH.