Validation of a rapid semi-automated method to assess left atrial longitudinal phasic strains on cine cardiovascular magnetic resonance imaging

BackgroundAbnormal left atrial (LA) function is a marker of cardiac dysfunction and adverse cardiovascular outcome, but is difficult to assess, and hence not, routinely quantified. We aimed to determine the feasibility and effectiveness of a fast method to measure long-axis LA strain and strain rate (SR) with standard cardiovascular magnetic resonance (CMR) compared to conventional feature tracking (FT) derived longitudinal strain.MethodsWe studied 50 normal controls, 30 patients with hypertrophic cardiomyopathy, and 100 heart failure (HF) patients, including 40 with reduced ejection fraction (HFrEF), 30 mid-range ejection fraction (HFmrEF) and 30 preserved ejection fraction (HFpEF). LA longitudinal strain and SR parameters were derived by tracking the distance between the left atrioventricular junction and a user-defined point at the mid posterior LA wall on standard cine CMR two- and four-chamber views. LA performance was analyzed at three distinct cardiac phases: reservoir function (reservoir strain epsilon(s) and strain rate SRs), conduit function (conduit strain epsilon(e) and strain rate SRe) and booster pump function (booster strain epsilon(a) and strain rate SRa).ResultsThere was good agreement between LA longitudinal strain and SR assessed using the fast and conventional FT-CMR approaches (r=0.89 to 0.99, p<0.001). The fast strain and SRs showed a better intra- and inter-observer reproducibility and a 55% reduction in evaluation time (8510 vs. 190 +/- 12s, p<0.001) compared to FT-CMR. Fast LA measurements in normal controls were 35.3 +/- 5.2% for epsilon(s), 18.1 +/- 4.3% for epsilon(e), 17.2 +/- 3.5% for epsilon(a), and 1.8 +/- 0.4, -2.0 +/- 0.5, -2.3 +/- 0.6s(-1) for the respective phasic SRs. Significantly reduced LA strains and SRs were observed in all patient groups compared to normal controls. Patients with HFpEF and HFmrEF had significantly smaller epsilon(s), SRs, epsilon(e) and SRe than hypertrophic cardiomyopathy, and HFmrEF had significantly impaired LA reservoir and booster function compared to HFpEF. The fast LA strains and SRs were similar to FT-CMR for discriminating patients from controls (area under the curve (AUC)=0.79 to 0.96 vs. 0.76 to 0.93, p=NS).Conclusions Novel quantitative LA strain and SR derived from conventional cine CMR images are fast assessable parameters for LA phasic function analysis.