Right Ventricular Strain Curve Morphology and Outcome in Idiopathic Pulmonary Arterial Hypertension

Objectives: The purpose of this study was to explore speckle tracking echocardiographic right ventricular (RV) post-systolic strain patterns and their clinical relevance in idiopathic pulmonary arterial hypertension (PAH). Background: The imaging of RV diastolic function in PAH remains incompletely understood. Methods: Speckle tracking echocardiography of RV post-systolic strain recordings were examined in 108 consecutive idiopathic patients with PAH. Each of them underwent baseline clinical, hemodynamic, and complete echocardiographic evaluation and follow-up. Results: In total, 3 post-systolic strain patterns derived from the mid-basal RV free wall segments were identified. Pattern 1 was characterized by prompt return of strain-time curves to baseline after peak systolic negativity, like in normal control subjects. Pattern 2 was characterized by persisting negativity of strain-time curves well into diastole, before an end-diastolic returning to baseline. Pattern 3 was characterized by a slow return of strain-time curves to baseline during diastole. The 3 patterns corresponded respectively to mild PH, more advanced PH but with still preserved RV function, and PH with obvious end-stage right heart failure. Patterns were characterized by optimal reproducibility when complementary to quantitative measurement of right ventricular longitudinal early diastolic strain rate (RVLSR-E), and right ventricular longitudinal late diastolic strain rate (RVLSR-A) (Cohen's κ = 0.88; p = 0.0001). Multivariable models for clinical worsening prediction demonstrated that the addition of RV post-systolic patterns to clinical and hemodynamic variables significantly increased their prognostic power (0.78 vs. 0.66; p < 0.001). Freedom from clinical worsening rates at 1 and 2 years from baseline were, respectively, 100% and 93% for Pattern 1; 80% and 55% for Pattern 2; and 60% and 33% for Pattern 3. Conclusions: Speckle tracking echocardiography allows for the identification of 3 phenotypically distinct, reproducible, and clinically meaningful RV strain-derived post-systolic patterns.