Rest and exercise hemodynamic and metabolic findings in active duty soldiers referred for cardiac catheterization to exclude heart disease: Insights from past invasive cardiopulmonary exercise testing using multisensor high fidelity catheters

Exercise MR-proANP unmasks latent right heart failure in CTEPH

OBJECTIVE

The present study was designed to investigate the dynamics of right atrial pressure (RAP) and mid-regional pro-atrial natriuretic peptide (MR-proANP) during physical exercise in patients with chronic thromboembolic pulmonary hypertension (CTEPH) and to determine whether these parameters might serve as a tool to measure exercise-dependent atrial stress as an indicator of right heart failure.

METHODS

This prospective observational cohort study included 100 CTEPH patients who underwent right heart catheterization during physical exercise (eRHC). Blood samples for MR-proANP measurement were taken prior, during, and after eRHC. MR-proANP levels were correlated to RAP levels at rest, at peak exercise (eRAP), and during recovery. RAP at rest ≤7 mmHg was defined as normal and eRAP >15 mmHg as suggestive of right heart failure.

RESULTS

During eRHC mean RAP increased from 6 mmHg (standard deviation, SD 4) to 16 mmHg (SD 7; p < 0.001). MR-proANP levels and dynamics correlated with RAP at rest (r_s = 0.61; p < 0.001) and at peak exercise (r_s = 0.66; p < 0.001). Logistic regression analysis revealed the peak MR-proANP level (B = 0.058; p = 0.004) and the right atrial area (B = 0.389; p < 0.001) to be associated with eRAP dynamics. A peak MR-proANP level ≥139 pmol/L (AUC = 0.81) and recovery level ≥159 pmol/L (AUC = 0.82) predicted an eRAP >15 mmHg. Physical exercise unmasked right heart failure in 39% of patients with normal RAP at rest; these patients were also characterized by a more distinct increase in MR-proANP levels (p = 0.005) and higher peak (p < 0.001) and recovery levels (p < 0.001).

CONCLUSIONS

RAP and MR-proANP dynamics unmask manifest and latent right heart failure in CTEPH patients.

Right Atrial Pressure During Exercise Predicts Survival in Patients With Pulmonary Hypertension

Background We investigated changes in right atrial pressure (RAP) during exercise and their prognostic significance in patients assessed for pulmonary hypertension (PH). Methods and Results Consecutive right heart catheterization data, including RAP recorded during supine, stepwise cycle exercise in 270 patients evaluated for PH, were analyzed retrospectively and compared among groups of patients with PH (mean pulmonary artery pressure [mPAP] ≥25 mm Hg), exercise-induced PH (exPH; resting mPAP <25 mm Hg, exercise mPAP >30 mm Hg, and mPAP/cardiac output >3 Wood Units (WU)), and without PH (noPH). We investigated RAP changes during exercise and survival over a median (quartiles) observation period of 3.7 (2.8-5.6) years. In 152 patients with PH, 58 with exPH, and 60 with noPH, median (quartiles) resting RAP was 8 (6-11), 6 (4-8), and 6 (4-8) mm Hg (P<0.005 for noPH and exPH versus PH). Corresponding peak changes (95% CI) in RAP during exercise were 5 (4-6), 3 (2-4), and -1 (-2 to 0) mm Hg (noPH versus PH P<0.001, noPH versus exPH P=0.027). RAP increase during exercise correlated with mPAP/cardiac output increase (r=0.528, P<0.001). The risk of death or lung transplantation was higher in patients with exercise-induced RAP increase (hazard ratio, 4.24; 95% CI, 1.69-10.64; P=0.002) compared with patients with unaltered or decreasing RAP during exercise. Conclusions In patients evaluated for PH, RAP during exercise should not be assumed as constant. RAP increase during exercise, as observed in exPH and PH, reflects hemodynamic impairment and poor prognosis. Therefore, our data suggest that changes in RAP during exercise right heart catheterization are clinically important indexes of the cardiovascular function.

Synergy in the heart: RV systolic function plays a key role in optimizing LV performance during exercise

The right ventricle (RV) is often overlooked in the evaluation of cardiac performance and treatment of left ventricular (LV) heart diseases. However, recent evidence suggests the RV may play an important role in maintaining systemic cardiac function and delivering stroke volume (SV). We used exercise cardiac magnetic resonance and biomechanical modeling to investigate the role of the RV in LV stroke volume regulation. We studied SV augmentation during exercise by pharmacologically inducing negative chronotropy (sHRi) in healthy volunteers and investigating training-induced SV augmentation in endurance athletes. SV augmentation during exercise after sHRi is achieved differently in the two ventricles. In the RV, the larger SV is driven by increasing contraction down to lower end-systolic volume (ESV; P < 0.001). In the LV, SV augmentation is achieved through an increase in end-diastolic volume (EDV; P < 0.001), avoiding contraction to a lower ESV. The same mechanism underlies the enhanced SV response observed in athletes. Changes in atrial area during SV augmentation suggest that the improved LV EDV response is sustained by the larger RV contractions. Using our biomechanical model, we explain this behavior by showing that the RV systolic function-driven regulation of LV SV optimizes the energetic cost of LV contraction and leads to minimization of the total costs of biventricular contraction. In conclusion, this work provides mechanistic understanding of the pivotal role of the RV in optimizing LV SV during exercise. It demonstrates why optimizing RV function needs to become a key part of therapeutic strategies in patients and training for athletes.NEW & NOTEWORTHY The right ventricle appears to have an important impact on maintaining systemic cardiac function and delivering stroke volume. However, its exact role in supporting left ventricular function has so far been unclear. This study demonstrates a new mechanism of ventricular interaction that provides mechanistic understanding of the key importance of the right ventricle in driving cardiac performance.