Echocardiographic Assessment of Ventricular Asynchrony in Dilated Cardiomyopathy and Congenital Heart Disease: Tools and Hopes

Hypertrophic Cardiomyopathy Is Associated with More Severe Left Ventricular Dyssynchrony than Is Hypertensive Left Ventricular Hypertrophy

OBJECTIVE

To evaluate left ventricular (LV) dyssynchrony in patients with left ventricular hypertrophy (LVH), and to compare abnormalities associated with hypertrophic cardiomyopathy (HCM) and hypertensive heart disease (HHD) using 2D speckle tracking imaging.

METHODS

Basal, middle, and apical 2D LV short-axis images were acquired in 43 patients with LVH including 20 with HCM and 23 with HHD, and in 15 age-matched controls. Radial strain, circumferential strain, time interval from the R-wave to peak radial strain (Trs), and time to peak circumferential strain (Tcs) were measured in six equidistant segments at each level of the 3 LV short-axis views using 2D speckle tracking analysis. To assess LV dyssynchrony, Trs(cs)-18SD, the standard deviation (SD) of Trs(cs) in all 18 segments, was calculated.

RESULTS

Regional radial strain in the middle and apical short-axis segments was significantly less in patients with HCM than in those with HHD. Regional circumferential strain in the apical short-axis segments was also less in HCM. Trs-18SD and Tcs-18SD were significantly longer in patients with HCM than in age-matched controls and patients with HHD (Trs-18SD: HCM: 88 +/- 32 ms, HHD: 51 +/- 20 ms, control: 45 +/- 12 ms P < 0.001, Tcs-18SD: HCM: 71 +/- 27 ms, HHD: 46 +/- 14 ms, control: 45 +/- 14 ms P < 0.001).

CONCLUSIONS

The presence of LVH is thus not always associated with LV dyssynchrony. However, the greater reduction of regional strain and severe LV dyssynchrony in HCM may contribute to the adverse cardiovascular outcomes associated with this disease.

Sudden death prophylaxis in heart failure

Sudden cardiac death (SCD) is the leading cause of mortality in heart failure (HF). Today the implantable cardioverter-defibrillator (ICD) has become a commonplace therapy around the world for patients with both ischemic and non-ischemic cardiomyopathy and an ejection fraction (EF) < or = 35%. However, EF alone does not discriminate between the modes of death from HF (sudden arrhythmic death vs. non-sudden death). Other risk statifiers, such as electrophysiologic study and microvolt T-wave alternans testing, should therefore be used in the appropriate settings to minimize the number of unnecessary device implants. In addition, left ventricular mechanical dyssynchrony has now become recognized as an additional major marker of cardiac mortality. Its assessment should entail echocardiography rather than measurement of the QRS duration. This will allow us to better integrate the ability of cardiac resynchronization therapy (CRT) in enhancing cardiac function with the ability of an ICD in preventing SCD. This review aims to: 1) give a synthesis of the published evidence regarding the value of implantable ICDs and CRT in the primary prophylaxis of SCD in HF; 2) discuss controversial clinical issues in this area; and 3) recommend practical device-based management strategies.

Triplane Tissue Doppler Imaging to Evaluate Mechanical Dyssynchrony Before and After Cardiac Resynchronization in a Patient with Congenitally Corrected Transposition of the Great Arteries

We report the case of a 13-year-old girl with congenitally corrected transposition of the great arteries. Since the implantation of a conventional pacemaker for acquired complete atrioventricular block, the patient experienced increased heart failure symptoms. Using triplane tissue Doppler imaging, significant intraventricular dyssynchrony induced by unilateral pacing and associated with diminished exercise capacity was demonstrated. A biventricular pacemaker was successfully implanted transvenously, leading to synchronous activation of the systemic ventricle and improved exercise capacity.