Clinically significant change in stroke volume in pulmonary hypertension.

BACKGROUND: Stroke volume is probably the best hemodynamic parameter because it reflects therapeutic changes and contains prognostic information in pulmonary hypertension (PH). Stroke volume directly reflects right ventricular function in response to its load, without the correction of compensatory increased heart rate as is the case for cardiac output. For this reason, stroke volume, which can be measured noninvasively, is an important hemodynamic parameter to monitor during treatment. However, the extent of change in stroke volume that constitutes a clinically significant change is unknown. The aim of this study was to determine the minimal important difference (MID) in stroke volume in PH. METHODS: One hundred eleven patients were evaluated at baseline and after 1 year of follow-up with a 6-min walk test (6MWT) and cardiac MRI. Using the anchor-based method with 6MWT as the anchor, and the distribution-based method, the MID of stroke volume change could be determined. RESULTS: After 1 year of treatment, there was, on average, a significant increase in stroke volume and 6MWT. The change in stroke volume was related to the change in 6MWT. Using the anchor-based method, an MID of 10 mL in stroke volume was calculated. The distribution-based method resulted in an MID of 8 to 12 mL. CONCLUSIONS: Both methods showed that a 10-mL change in stroke volume during follow-up should be considered as clinically relevant. This value can be used to interpret changes in stroke volume during clinical follow-up in PH.

Relation of resting heart rate to prognosis in patients with idiopathic pulmonary arterial hypertension.

Heart rate (HR) at rest is an important marker of prognosis in heart failure, but has not been addressed in pulmonary arterial hypertension (PAH). To determine the prognostic value of HR at rest in patients with PAH, we retrospectively analyzed 140 consecutive patients with idiopathic PAH. Electrocardiogram (ECG)-derived HR at rest was evaluated as a potential predictor of adverse prognosis (death or lung transplantation), in addition to World Health Organization functional class, 6-minute walk distance, and hemodynamics before and approximately 1 year and 2 years after initiation of PAH treatment. During follow-up, 49 patients (35%) died, and 5 patients (4%) underwent lung transplantation. Before treatment initiation and after 1 year and 2 years of treatment, respectively, a higher HR at rest was an independent predictor of adverse prognosis (hazard ratios per 10-beats/min increase 1.76, 95% confidence interval 1.42 to 2.18, 2.31, 95% confidence interval 1.58 to 3.38, 2.1, 95% confidence interval 1.39 to 3.19, respectively, p <0.001 for all). Change in HR between the first and last ECG also independently predicted prognosis (hazard ratio per 1-beat/min increase 1.03, 95% confidence interval 1.01 to 1.06). In conclusion, a higher HR at rest and an important increase in HR at rest during follow-up signify a considerable risk of death in patients with PAH. ECG-derived HR at rest is an important marker of prognosis and should be assessed before and at frequent intervals after initiation of treatment for PAH.

ECG monitoring of treatment response in pulmonary arterial hypertension patients.

BACKGROUND: The potential use of the ECG for monitoring treatment effects in patients with pulmonary arterial hypertension (PAH) has not been investigated. We evaluated whether the ECG is useful for monitoring treatment response based on changes in pulmonary vascular resistance (PVR). METHODS: An ECG was recorded in 81 PAH patients at the time of diagnostic right heart catheterization and after 1 year of treatment. Patients were treated according to the guidelines. Patients were divided into two groups based on PVR (ie, < 500 or > 500 dyne x s x cm(-5)). A positive treatment response was defined as a > 25% decrease in PVR to an absolute PVR of < 500 dyne x s x cm(-5). RESULTS: At baseline, the 19 patients with a PVR of < 500 dyne x s x cm(-5) had a significantly lower P amplitude in lead II, a less rightward oriented QRS axis, and a more rightward T axis than the 62 patients with a PVR of > 500 dyne x s x cm(-5). Overall (n = 81), the mean (+/- SD) change in PVR was -143 +/- 360 dyne x s x cm(-5) after 1 year of treatment (p < 0.001). Twelve patients (19%) with a baseline PVR of > 500 dyne x s x cm(-5) were classified as responders. Receiver operating characteristic analysis determined that the P amplitude in lead II (area under the curve [AUC], 0.80; 95% confidence interval [CI], 0.67 to 0.94; p < 0.01), QRS axis (AUC, 0.70; 95% CI, 0.52 to 0.89; p = 0.03), and T axis (AUC, 0.90; 95% CI, 0.82 to 0.97; p < 0.001) were important determinants of treatment response. The presence of a P amplitude in lead II of < 0.175 mV and a T axis of >or= 25 degrees combined had a positive and negative predictive value for treatment response of 0.81 (95% CI, 0.37 to 0.96) and 0.94 (95% CI, 0.86 to 0.99), respectively. CONCLUSIONS: Routine ECG evaluation can be an important contribution in the assessment of treatment response in PAH patients.

Right coronary artery flow impairment in patients with pulmonary hypertension.

AIMS: This study investigates whether increased right ventricular (RV) pressure in pulmonary hypertension (PH) impairs right coronary artery (RCA) flow and RV perfusion. METHODS: In 25 subjects, five patients with idiopathic pulmonary arterial hypertension, nine patients with chronic thromboembolic pulmonary arterial hypertension, and 11 healthy controls, flow of the RCA and left anterior descending (LAD) artery was measured with MR flow quantification. RESULTS: In PH, RCA peak systolic and mean systolic flow were lower, 1.02 +/- 0.62 mL/s and 0.42 +/- 0.30 mL/s, than peak and mean diastolic flow, 2.99 +/- 1.97 mL/s (P < 0.001) and 1.73 +/- 0.97 mL/s (P < 0.001); a pattern similar to the LAD. In contrast, in controls, RCA peak and mean flow in systole, 1.63 +/- 0.58 mL/s and 0.72 +/- 0.23 mL/s, were comparable to peak and mean flow in diastole, 1.72 +/- 0.48 mL/s and 0.93 +/- 0.28 mL/s (NS). The systolic-to-diastolic flow ratio in the RCA, and mean flow per gram RV tissue, were inversely related to RV mass, R = -0.61 (P = 0.009), and R = -0.73 (P < 0.001) and to RV pressure, R = -0.83 (P < 0.001), and R = -0.57 (P = 0.033). CONCLUSION: Although in controls, RCA flow is similar in systole and diastole, in PH there is systolic flow impediment, which is proportional to RV pressure and mass. In patients with severe RV hypertrophy total mean flow is reduced.

Prognostic value of right ventricular mass, volume, and function in idiopathic pulmonary arterial hypertension.

AIMS: This study investigated the relationship between right ventricular (RV) structure and function and survival in idiopathic pulmonary arterial hypertension (IPAH). METHODS AND RESULTS: In 64 patients, cardiac magnetic resonance, right heart catheterization, and the six-minute walk test (6MWT) were performed at baseline and after 1-year follow-up. RV structure and function were analysed as predictors of mortality. During a mean follow-up of 32 months, 19 patients died. A low stroke volume (SV), RV dilatation, and impaired left ventricular (LV) filling independently predicted mortality. In addition, a further decrease in SV, progressive RV dilatation, and further decrease in LV end-diastolic volume (LVEDV) at 1-year follow-up were the strongest predictors of mortality. According to Kaplan-Meier survival curves, survival was lower in patients with an inframedian SV index or= 84 mL/m(2), and an inframedian LVEDV