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Left Ventricular Mechanical Dyssynchrony in Acute Onset Cardiomyopathy: Association of Its Resolution With Improvements in Ventricular Function
Study Questions:
What is the impact of mechanical dyssynchrony in patients with acute onset cardiomyopathy with narrow QRS interval, and what is its association with improvements in left ventricular (LV) function?
Methods:
The study cohort was comprised of 201 patients enrolled in the IMAC-2 (Inflammatory Mediators in Acute Cardiomyopathy) trial with recent onset nonischemic cardiomyopathy and ejection fraction <40%. The study investigators assessed: 1) ventricular dyssynchrony using speckle-tracking velocity vector imaging, and 2) diastolic function by mitral inflow E and mitral E’ annular velocities (E/E’). The control group was comprised of 15 normal volunteers.
Results:
The study investigators found that 54% of patients (n = 108) had significant LV dyssynchrony at presentation: opposing wall delay 89 ± 51 ms versus 35 ± 11 ms in controls, and 12-site standard deviation 43 ± 23 versus 24 ± 8 ms in controls (p < 0.001) despite a narrow QRS complex (mean 98 ± 21 ms). The diastolic dysfunction was greater (E/E’ 15 ± 8 versus 12 ± 6, p < 0.05) in patients with ventricular dyssynchrony. The investigators also found that mean ejection fraction improved from 23 ± 8% to 40 ± 12%, and E/E’ improved from 14 ±7 to 9 ± 5 (both p < 0.001) at the end of 6 months. Dyssynchrony improved from 89 ± 51 ms to 52 ± 35 ms in maximum opposing wall delay, and 43 ± 23 ms to 32 ± 19 ms in 12-site standard deviation, and the prevalence of dyssynchrony decreased to 12% after 6 months (p < 0.001 vs. baseline).
Conclusions:
The investigators concluded that mechanical dyssynchrony was not uncommon in acute onset cardiomyopathy, despite having a narrow QRS interval. They also concluded that resolution of LV dyssynchrony is associated with improvements in LV systolic function.
Perspective:
Given that the natural history of acute onset cardiomyopathy is variable, the findings of this study are important. The next step would be to determine whether LV dyssynchrony is a predictor of recovery of LV systolic function. If so, the next move would be to determine optimal therapy that will promote recovery of LV systolic function.
Keywords: Ventricular Function, Left, Cardiomyopathies, Heart Failure, Diastole, Heart Ventricles, Systole
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