Purpose: Using a cardiac magnetic resonance (CMR) approach we investigated left ventricular (LV) myocardial changes associated with pulmonary arterial hypertension (PAH) by strain analysis and mapping techniques.
Materials and methods: Seventeen patients with PAH (9 men; mean age, 64.2±13.6 y) and 20 controls (10 men, 63.2±10.5 y) were examined using CMR at 1.5 T. Native LV T1-relaxation times (T1) and extracellular volume fraction (ECV) were assessed using a MOLLI sequence, T2-relaxation times (T2) by means of a gradient spin-echo sequence, and LV longitudinal strain (LVS) and right ventricular (RV) longitudinal strain (RVS) by means of CMR feature tracking. The hematocrit and serum levels of pro-Brain Natriuretic Peptide were determined on the day of the CMR examination. Pulmonary arterial pressure and 6-minute walking distance were assessed as part of the clinical evaluation.
Results: T1 and ECV were higher (1048.5±46.6 vs. 968.3±22.9 ms and 32.4%±5.7% vs. 28.4%±3.8%; P<0.05) and LVS was lower in patients with PAH (-18.0±5.6 vs. -23.0±2.9; P<0.01) compared with controls. LV mass and interventricular septal thickness were lower in PAH patients (65.7±18.0 vs. 86.7±26.9 g and 7.6±1.9 vs. 10±2.4 mm; P<0.05); there were no differences in LV ejection fraction (61.2%±6.9% vs. 61.9%±6.7%; P=0.86). T1-derived parameters correlated significantly with RVS, LVS, the 6-minute walking distance, RV ejection fraction, pro-Brain Natriuretic Peptide, and baseline mean pulmonary arterial pressure. There were no significant differences in T2.
Conclusions: In patients with PAH, changes in T1 and ECV support the hypothesis of LV myocardial fibrosis and atrophy with a consecutively impaired contractility despite a preserved LV function, possibly due to longstanding PAH-associated LV underfilling.