Mechanical dispersion in Fabry disease assessed with speckle tracking echocardiography

BACKGROUND

Fabry disease (FD) is a rare X-linked storage disorder caused by deficiency of the lysosomal enzyme α-galactosidase A, and it typically causes multiorgan dysfunction. The main cause of death is heart disease resulting from left ventricular (LV) diastolic dysfunction, LV systolic dysfunction, severe LV hypertrophy (LVH), and sudden death. In several cardiac disorders, LV systolic dysfunction and ventricular arrhythmias are associated with mechanical dispersion (MD). MD has until now not been studied in patients with FD.

OBJECTIVE

To investigate the prevalence of MD in patients with FD.

METHODS

Complete echocardiographic data and speckle tracking echocardiographic data were collected. MD is an index of inter-segmental discoordination of contraction and is defined as the standard deviation (SD) of the time-to-peak longitudinal negative strain in 17 LV segments with a value >49 milliseconds. Patients with FD were divided into the following 2 groups: group I (patients with FD but no LVH, n = 64) and group II (patients with FD and LVH, n = 25). These groups were compared with a group of healthy subjects (group III, n = 50). Parametric variables were expressed as mean ± SD, and nonparametric variables were expressed as median and inter-quartile range. A P value <.05 was considered significant.

RESULTS

A total of 113 patients with FD were included in this study. Of these, 24 (21%) were excluded because of poor imaging quality or presence of comorbidities, and the final study population consisted of 89 patients (mean age of 33.5 ± 14.5 years, 64% female). Group II patients were older than group I patients (46 ± 13 years vs 27 ± 11 years, P < .0001). There was no difference in LV ejection fraction between the 3 groups. There was also no difference in MD between groups I and III (32.4 ms [26-39] vs 32 ms [26-39]). In group II, the MD in 19 patients (76%) was 56 ms (39-80).

CONCLUSIONS

To the best of our knowledge, this is the first study to assess the prevalence of MD in patients with FD. MD was observed in 76% of patients with FD and LVH. The use of MD in strain echocardiography may be beneficial in the assessment of patients with FD who develop heart failure.

4091Mechanical dispersion by speckle tracking echocardiography in fabry disease

Background

Fabry disease is a rare X-linked storage disorder caused by a deficiency of the lysosomal enzyme α-galactosidase A and generally causes multi-organ dysfunction. Heart disease is the main cause of death, due to severe left ventricular (LV) systolic dysfunction and sudden death. In several heart diseases, the LV systolic dysfunction and ventricular arrhythmias are associated with mechanical dispersion (MD). The presence of MD in patients with FD has not been studied yet. In this cross-sectional study, we investigated the prevalence of MD in patients with FD.

Methods

Complete echocardiographic and speckle tracking echocardiographic (STE) data were collected. MD is an index of inter-segmental discoordination of contraction which has been used to quantify LV dyssynchrony and was defined as the standard deviation (SD) of time to peak negative strain in 17 left ventricular segments. Patients were divided into two groups according to whether or not they had left ventricular hypertrophy (LVH). MD was defined as an SD >49 msec.

Results

We studied 108 patients with FD, 24 patients (22%) were excluded due to inadequate imaging quality or presence of comorbidities, so the final study population consisted of 84 patients (mean age 33.3±14.6 years, 60.7% women). LVH in FD appears at older ages than in patients without LVH (48±12.5 y/o vs 27.8±11.1 y/o, p<0.0001). Patients with FD without LVH (Group I) showed normal global longitudinal peak strain (GLPS) (21.2±2.5%) and no MD (32.7±8.8 msec). In Group II (n=23) patients with FD with LVH, 17 (73.9%) had MD >49 msec prolonged mechanical dispersion (73.3±20.7 msec) and reduced GLPS (13.6±4.0%). MD was more pronounced in Fabry patients with LVH than in patients without LVH (63.4±24.7 msec vs. 32.7±8.8 msec, p<0.0001). GLPS was lower in Fabry patients with LVH than in patients without LVH (15.3±4.7% vs 21.2±2.5%, p<0.0001).

Figure 1

Conclusions

To our knowledge, this is the first study to demonstrate the prevalence of mechanical dispersion in patients with FD. Mechanical dispersion was seen in 73.9% of patients with FD with LVH. This dyssynchrony should be taken into account in patients who develop heart failure or life-threatening ventricular tachyarrhythmias.

Left cavities spontaneous contrast opacification

We report a transesophageal echocardiography study of a patient in a critical care unit under mechanical respiratory assistance in whom left cavities spontaneous contrast opacification was seen, suggesting systemic gas embolism as the probable mechanism.

Estimation of the ejection fraction in patients with myocardial infarction obtained from the combined index of systolic and diastolic left ventricular function: a new method

The index of myocardial performance combining systolic and diastolic time intervals (Index) is a useful method, already explained in past studies, that offers new values that have not been widely known among clinical cardiologists. The aim of this study is to obtain from this Index a measurement of the ejection fraction (EF), which is a very well-known value. The study involved 97 patients with myocardial infarction, 55 of whom were studied retrospectively (group A, aged 46-62 years, 50 men) to obtain and test the formula EF = 60 - (34 x Index). The second group (group B, aged 47-63 years, 40 men) included 42 patients who were evaluated prospectively. The EF obtained was compared with that reached through the use of radionuclide angiography (EF-RNA). The Index was obtained through the use of the formula (a - b)/b, where a is the interval between cessation and onset of the mitral inflow, and b is the ejection time. In group A the EF obtained by the Index (EF-Index) was 37.5% +/-.8%, and the EF-RNA was 37.7% +/- 11% (r = 0.76). In group B the EF-Index was 41.6% +/- 7%, and the EF-RNA was 41.2% +/- 10% (r = 0. 75).

CONCLUSION

Through the new formula described here it is possible to obtain a reliable measurement of the EF in patients with myocardial infarction, a well-known and extremely useful value, especially for those patients with poor acoustic windows.