2D Parameters of Left Ventricular Size
This meta-analysis demonstrated that half of the studies featured
quantifiable changes in LV end-diastolic diameter, a marker of
structural myocardial remodeling, thus potentially useful as a
discriminator between myocarditis and control populations although not
strong. Measurement of LV diameter was demonstrated to have the lowest
overall effect size when compared to the parameters of LV function which
was consistent with the notion that measures of LV function being more
sensitive for the detection of underlying myocardial pathology compared
to measures of LV structural change(20). Identification of
increased LV diameter may also be reflective of the chronicity of
disease hence effective in distinguishing more chronic or fulminant
myocarditis, which would also be more likely to have other
echocardiographic abnormalities such as regional wall motion
abnormalities and impaired LV systolic function, as demonstrated in two
of the included studies (13,
14).
Only four out of the six studies included in this systematic review
reported LV volumes with only one study reporting significant
differences in indexed volumes. The heterogeneity in the methodology for
the assessment of LV volumes did not allow for meta-analysis of this
parameter although it is postulated that LV volume changes would provide
a more accurate reflection of LV structural change compared to linear
measurements of LV size changes. Moreover, current guidelines do not
recommend use of LVEDD for routine quantification of LV size but indexed
volumes instead. Whilst LV dilatation has been hypothesized to be
associated with an increased risk of heart failure, LV volumes have been
shown to more accurately reflect LV remodeling, in comparison to single
dimensional assessment (21,
22). One study did demonstrate that
indexed left ventricular end-diastolic volumes were greater in their
cohort of myocarditis patients compared to controls consistent with
expectations. However, the remaining studies reporting non-indexed LV
volumes did not demonstrate any significant differences between
myocarditis populations and controls. This finding is largely thought to
be attributed to the non-indexation of LV volumes, limiting its
precision and accuracy.