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

Background

Abnormal 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.

Methods

We 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 ε_s and strain rate SR_s), conduit function (conduit strain ε_e and strain rate SR_e) and booster pump function (booster strain ε_a and strain rate SR_a).

Results

There 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 (85?±?10 vs. 190?±?12 s, p?<?0.001) compared to FT-CMR. Fast LA measurements in normal controls were 35.3?±?5.2% for ε_s, 18.1?±?4.3% for ε_e, 17.2?±?3.5% for ε_a, and 1.8?±?0.4, ??2.0?±?0.5, ??2.3?±?0.6 s^??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 ε_s, SR_s, ε_e and SR_e 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.