Left ventricular tissue phase mapping predicts PAH outcomes

By Eleanor McDermid, Senior medwireNews Reporter

A tissue phase mapping study shows that left ventricular (LV) function is abnormal in patients with pulmonary arterial hypertension (PAH) and is linked to clinical outcomes.

“These results demonstrate that LV myocardial mechanics are negatively affected by RV [right ventricular] pressure overload and may contribute to symptoms and clinical worsening”, the researchers write in the Journal of Cardiovascular Magnetic Resonance.

The 40 PAH patients in the study all had preserved LV ejection fraction. Yet, when compared with 20 age- and gender-matched healthy volunteers, they had significantly reduced LV end-diastolic volume (88 vs 134 mL) and systolic volume (62 vs 85 mL), as well as LV cardiac output (4.6 vs 5.6 L/min). Septal curvature was lower, and was in fact reversed in 65% of the PAH patients.

And LV filling velocity was significantly impaired in the PAH patients versus the controls. Specifically, the team found that PAH “is primarily associated with early diastolic LV dysfunction”, with peak E wave radial and longitudinal velocities significantly reduced, at 2.3 versus 3.1 cm/s and 2.6 versus 4.2 cm/s, respectively.

Moreover, all the PAH patients had a reversed tangential E1 wave velocity, compared with just four controls and 32 versus two had a reversed tangential E2 wave velocity. Reversal of both tangential E wave velocities was “highly discriminatory” for PAH, says the team.

Early LV filling velocity was also associated with clinical condition; E wave radial velocity was independently associated with 6-minute walk distance while longitudinal velocity predicted clinical worsening.

“This is probably because patients with impaired diastolic function have less cardiac reserve and are therefore more symptomatic”, say Vivek Muthurangu (UCL Medical School, London, UK) and study co-authors. “This increases the likelihood of up-titration of therapy or death.”

The team observes that the E/A ratio did not differ between PAH patients and controls and was not associated with clinical outcomes, implying that tissue phase mapping markers may be superior to conventional measures of diastolic function.

They also note that RV ejection fraction was not independently associated with either exercise capacity or clinical worsening, suggesting “that reduced LV diastolic function may be more important than RV function itself.”

The researchers conclude: “Future work should […] be directed at assessing the response of these novel biomarkers to vasodilator therapy.”

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