Refer to the page 398-407
Pulmonary arterial hypertension (PAH) is a syndrome in which pulmonary arterial obstruction increases pulmonary vascular resistance (PVR) leading to right ventricle (RV) failure. Progression and survival of patients with PAH are related to the ability of the RV to adapt to the chronically elevated pulmonary artery pressure (PAP),1) hence, RV function is an important determinant of prognosis in PAH. However, noninvasive assessment of RV function is often limited by complex geometry and poor endocardial definition. Conventional parameters such as tricuspid annular plane systolic excursion <17 mm and RV fractional area change <35% are used to evaluate RV function and the current guideline recommends these parameters for estimating RV function.2),3),4) However, these measurements have limitations to represent the global function of RV due to its complex geometry.5),6)
Novel techniques such as RV longitudinal strain or RV myocardial performance index can evaluate RV function.7),8) The longitudinal muscle fiber orientation of RV results in systolic motion, which is largely in the longitudinal plane with the RV base moving toward the apex. Therefore, RV longitudinal strain assessed with speckle tracking is relatively angle independent and provides more global function assessment.9) A recent study showed that RV longitudinal peak systolic strain is a significant prognostic determinant in patients with PAH.10) However, published reports on the accuracy of 2-dimensional echocardiography-derived RV strain against an independent reference in PAH patients are limited. Freed et al.11) showed that RV longitudinal strain assessed with 2-dimensional speckle tracking provides a good alternative for cardiovascular magnetic resonance-derived RV ejection fraction in patients with PAH.
Recently, Park et al.12) reported that baseline RV longitudinal strain correlates with functional capacity (6-minute walking distance, r=-0.54, p<0.01), biomarker (LogBNP, r=0.65, p<0.01) and invasive hemodynamic parameters (mean PAP, r=0.35, p<0.05; cardiac index, r=0.50, p<0.01; PVR, r=-0.45, p=0.01) by right heart catheterization in PAH patients. They also showed that RV longitudinal strain changes in parallel with the changes of invasively measured mean PAP and PVR; and the changes in RV longitudinal strain reflect changes in specific pulmonary vasodilator treatment during follow-up. These findings implicate that in addition to the prognostic value of single measurement of RV longitudinal strain, serial non-invasive echocardiographic assessment of RV longitudinal strain may predict clinical deterioration in patients with PAH after initiating medical therapy. Although this retrospective and observational study had major limitations with relatively small numbers of PAH patients, this work has valuable clinical meaning, because one of the most important issues in PAH is to resolve the discrepancy between the prognosis of patients with PAH and PVR with modern pharmacotherapy. RV function can deteriorate in patients with PAH, despite the apparent success of therapy indicated by the reduction in PVR; furthermore, a deterioration of RV function is associated with a poor outcome, irrespective of the trends in PVR.13) Accordingly, the staging of patients by degree of RV longitudinal strain reduction might be useful in predicting survival in patients before and after initiation of medical therapy. In addition, RV longitudinal strain is a potential non-invasive target indicator in the treatment of PAH.
Footnotes
The authors have no financial conflicts of interest.
References
- 1.Ghio S, Klersy C, Magrini G, et al. Prognostic relevance of the echocardiographic assessment of right ventricular function in patients with idiopathic pulmonary arterial hypertension. Int J Cardiol. 2010;140:272–278. doi: 10.1016/j.ijcard.2008.11.051. [DOI] [PubMed] [Google Scholar]
- 2.Forfia PR, Fisher MR, Mathai SC, et al. Tricuspid annular displacement predicts survival in pulmonary hypertension. Am J Respir Crit Care Med. 2006;174:1034–1041. doi: 10.1164/rccm.200604-547OC. [DOI] [PubMed] [Google Scholar]
- 3.Rudski LG, Lai WW, Afilalo J, et al. Guidelines for the echocardiographic assessment of the right heart in adults: a report from the American Society of Echocardiography endorsed by the European Association of Echocardiography, a registered branch of the European Society of Cardiology, and the Canadian Society of Echocardiography. J Am Soc Echocardiogr. 2010;23:685–713. doi: 10.1016/j.echo.2010.05.010. quiz 786-8. [DOI] [PubMed] [Google Scholar]
- 4.Galiè N, Hoeper MM, Humbert M, et al. Guidelines for the diagnosis and treatment of pulmonary hypertension: the Task Force for the Diagnosis and Treatment of Pulmonary Hypertension of the European Society of Cardiology (ESC) and the European Respiratory Society (ERS), endorsed by the International Society of Heart and Lung Transplantation (ISHLT) Eur Heart J. 2009;30:2493–2537. doi: 10.1093/eurheartj/ehp297. [DOI] [PubMed] [Google Scholar]
- 5.Kossaify A. Echocardiographic assessment of the right ventricle, from the conventional approach to speckle tracking and three-dimensional imaging, and insights into the "right way" to explore the forgotten chamber. Clin Med Insights Cardiol. 2015;9:65–75. doi: 10.4137/CMC.S27462. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Karas MG, Kizer JR. Echocardiographic assessment of the right ventricle and associated hemodynamics. Prog Cardiovasc Dis. 2012;55:144–160. doi: 10.1016/j.pcad.2012.07.011. [DOI] [PubMed] [Google Scholar]
- 7.Amundsen BH, Helle-Valle T, Edvardsen T, et al. Noninvasive myocardial strain measurement by speckle tracking echocardiography: validation against sonomicrometry and tagged magnetic resonance imaging. J Am Coll Cardiol. 2006;47:789–793. doi: 10.1016/j.jacc.2005.10.040. [DOI] [PubMed] [Google Scholar]
- 8.Schiller NB, Kwan DM. The Tei index as an expression of right ventricular impairment and recovery: investment grade or subprime? JACC Cardiovasc Imaging. 2009;2:150–152. doi: 10.1016/j.jcmg.2008.11.006. [DOI] [PubMed] [Google Scholar]
- 9.Pirat B, McCulloch ML, Zoghbi WA. Evaluation of global and regional right ventricular systolic function in patients with pulmonary hypertension using a novel speckle tracking method. Am J Cardiol. 2006;98:699–704. doi: 10.1016/j.amjcard.2006.03.056. [DOI] [PubMed] [Google Scholar]
- 10.Haeck ML, Scherptong RW, Marsan NA, et al. Prognostic value of right ventricular longitudinal peak systolic strain in patients with pulmonary hypertension. Circ Cardiovasc Imaging. 2012;5:628–636. doi: 10.1161/CIRCIMAGING.111.971465. [DOI] [PubMed] [Google Scholar]
- 11.Freed BH, Tsang W, Bhave NM, et al. Right ventricular strain in pulmonary arterial hypertension: a 2D echocardiography and cardiac magnetic resonance study. Echocardiography. 2015;32:257–263. doi: 10.1111/echo.12662. [DOI] [PubMed] [Google Scholar]
- 12.Park JH, Kusunose K, Kwon DH, et al. Relationship between right ventricular longitudinal strain, invasive hemodynamics, and functional assessment in pulmonary arterial hypertension. Korean Circ J. 2015;45:398–407. doi: 10.4070/kcj.2015.45.5.398. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.van de Veerdonk MC, Kind T, Marcus JT, et al. Progressive right ventricular dysfunction in patients with pulmonary arterial hypertension responding to therapy. J Am Coll Cardiol. 2011;58:2511–2519. doi: 10.1016/j.jacc.2011.06.068. [DOI] [PubMed] [Google Scholar]