Speckle myocardial imaging modalities for early detection of myocardial impairment in isolated left ventricular non-compaction

Abstract

Objective: To examine the hypothesis that speckle myocardial imaging (SMI) modalities, including longitudinal, radial and circumferential systolic (s) and diastolic (d) myocardial velocity imaging, displacement (D), strain rate (SR) and strain (S), as well as left ventricular (LV) rotation/torsion are sensitive for detecting early myocardial dysfunction in isolated LV non-compaction (iLVNC).

Design and results: Twenty patients with iLVNC diagnosed by cardiac magnetic resonance (15) or echocardiography (5) were included. Patients were divided into two groups: ejection fraction (EF)>50% (n=10) and EF<or=50% (n=10). Standard measures of systolic and diastolic function including pulsed wave tissue Doppler Imaging (PWTDI) were obtained. Longitudinal, radial and circumferential SMI, and LV rotation/torsion were compared with values for 20 age/sex-matched controls. EF, PWTDI E', E/E' and all of the SMI modalities were significantly abnormal for patients with EF<or=50% compared with controls. In contrast, EF and PWTDI E', E/E' were not significantly different between controls and patients with iLVNC (EF>50%). However, SMI-derived longitudinal sS, sSR, sD and radial sS, as well as LV rotation/torsion values, were all reduced in iLVNC (EF>50%) compared with controls. Measurements with the highest discriminating power between iLVNC (EF>50%) and controls were longitudinal sS mean of the six apical segments (area under the curve (AUC)=0.94), sS global average (AUC=0.94), LV rotation apical mean (AUC=0.94); LV torsion (AUC=0.93) LV torsion rate (AUC=0.94).

Conclusions: LV SMI values are reduced in patients with iLVNC, even those with normal EF and PWTDI. The most accurate SMI modalities to discriminate between patients and controls are longitudinal sS mean of the six apical segments, LV apical rotation or LV torsion rate.

Figure 1

a) Speckle myocardial imaging: speckle tracking of the lateral wall (apical four-chamber, narrow view) in a patient with overt isolated left ventricular non-compaction. The image was analysed offline with the help of a specific software (Echopac BTW09, GE Vingmend Ultrasound Medical Systems); tracking quality for each segment is reported at the bottom of the figure. (b) Cardiac magnetic resonance: short-axis cardiovascular magnetic resonance of a steady state free precession image illustrating severe myocardial trabeculation with deep intertrabecular recesses. Biventricular myocardial involvement with features consistent with non-compaction can be appreciated.

Figure 2

Comparison of longitudinal systolic strain (sS) of the left ventricle at the basal, mid and apical level, for each group. p Values were calculated using repeated-measures analysis of variance and denote differences across three segments from the base, mid and apex, and differences as a result of the interaction of group and level. *p<0.001 comparing the base, mid and apex within the same group.

Figure 3

Receiver operating characteristic (ROC) analysis for the speckle myocardial imaging (SMI) modalities, comparison between patients with isolated left ventricular non-compaction and ejection fraction >50% (group II) vs controls (group I). sS glob mean, mean of the sS values for 18 left ventricular (LV) segments; sS apical mean, mean of the sS values for six LV apical segments; sSR apical mean, mean of the sSR values for six LV apical segments; sD global mean, mean of the sD values for 18 LV segments; sD middle mean, mean of the sD values for six LV middle segments; Radial sS mean, radial sS mean of the six LV segments at level of the papillary muscles in short-axis (SAX) view; Circumferential sS mean, circumferential sS mean of the six LV segments at level of the papillary muscles in SAX view; Rotation apical mean, mean of the LV rotation for the six LV apical segments; Torsion: LV torsion (computed as (apical LV rotation – basal LV rotation)); Torsion rate, LV torsion rate (degrees/s). (a) SMI longitudinal measures; areas under the curve (AUCs) group II vs group I: sS global mean=0.90 (95% CI 0.82 to 1.00); sS apical mean=0.93 (95% CI 0.82 to 1.00); sS middle mean=0.94 (95% CI 0.72 to 1.00); sSR apical mean=0.80 (95% CI 0.63 to 0.98); sD global mean=0.87 (95% CI 0.74 to 1.00); sD middle mean=0.87 (95% CI 0.74 to 1.00). (b) SMI radial, circumferential, and LV rotation/torsion measures; AUCs group II vs group I: Radial sS mean=0.82 (95% CI 0.61 to 1.00); Circumferential sS mean=0.60 (0.26 to 0.93); LV rotation apical mean=0.94 (95% CI 0.83 to 1.00); LV torsion=0.93 (95% CI 0.81 to 1.00); LV torsion rate=0.94 (95% CI 0.84 to 1.00). (c) SMI best modalities; AUCs group II vs group I: sS apical mean, sS global mean, LV rotation apical mean, LV torsion, LV torsion rate. p Value for the ROC curves comparison=0.57.