Methods: Retrospective analysis of P with normal left ventricular ejection fraction who underwent a comprehensive TTE for HCM evaluation, in a tertiary centre. LA function was assessed by determination of longitudinal strain (LS) and strain rate (SR) in apical 4 chambers view in 3 phases: reservoir, conduit and pump booster. LV global longitudinal strain (GLS) was assessed in apical 4, 2 and 3 chambers view. Radial strain and strain rate was assessed at papillary muscles level in short axis view.
Results: 52 P were enrolled, mean age 66.5±15.9 years, 44% males, 38% with obstructive HCM.
LA SR in conduit and pump booster phases were worse in P with LA dilatation (>40mm) (- -0.43±037 vs -0.88±0.64 s-1, p=0.019 and -0.74±0.62 vs -1.08±0.27 s-1, p=0.037, respectively).
LA LS was substantially different in sinus rhythm and atrial fibrillation P (LS in conduit phase: 8.72±6.56 vs 0.52±2.53%, p=0.006; LS in reservoir phase: 13.29±8.17 vs 6.47±2.72%, p=0.036), as well as SR in reservoir phase (0.63±0.57 vs 0.38±0.25 s-1, p=0.048).
LA strain rate in conduit phase was significantly different in obstructive and non-obstructive HCM (-0.31±0.44 vs -0.65±0.42 s-1, p=0.002) suggesting a more relevant impairment in diastole, particularly in rapid filling phase, in obstructive HCM P.
In overall population, LV GLS was -13.92±6.82%, interventricular septum (IVS) peak longitudinal strain -7.53±6.82% and IVS peak radial strain 22.88±16.64%. There was not a significant difference in these parameters between obstructive and non-obstructive HCM.
There was a concordance between tissue Doppler (septal s’) and IVS peak radial strain. P with septal s’ >6 presented IVS peak radial strain of -12.67±10.67% contrasting with -5.84±5.08% in P with lower s’ (p=0.010).
IVS radial strain rate was higher in P with LA dilatation (2.36±1.13 vs 1.50±0.50 s-1, p=0.029).
P with impairment in LV function assessed by GLS (> -18%) presented lower LA SR in reservoir phase (0.56±0.49 vs 0.93±0.31s-1, p=0.010) and in pump booster phase (-0.70±0.54 vs -8.07±20.6s-1, p=0.016).
Conclusion: Changes in LA strain and strain rate were more evident in the presence of LA dilatation, atrial fibrillation and obstructive HCM. Even with a normal LV ejection fraction, HCM P presented an impairment in GLS, IVS peak longitudinal and radial strain. Lower Tissue Doppler velocity in IVS was associated with worse radial strain in this segment. There was a concordance between the impairment of LA and LV function assessed by strain study.