Clinical Investigation
Echocardiographic Assessment of Myocardial Scar
Myocardial Scar by Pulse-Cancellation Echocardiography Is Independently Associated with Appropriate Defibrillator Intervention for Primary Prevention after Myocardial Infarction

https://doi.org/10.1016/j.echo.2020.04.020Get rights and content

Highlights

  • eScar has been preliminarily validated in prior studies.

  • eScar was tested in patients with an implantable defibrillator after myocardial infarction.

  • Extent of eScar was independently associated with appropriate defibrillator shocks.

Background

Myocardial scar burden impacts prognosis in patients with coronary artery disease who have experienced a myocardial infarction (MI). This has been demonstrated by late gadolinium enhancement cardiac magnetic resonance. Clinical experience with echocardiography suggests that the reflected ultrasound signal is enhanced in infarcted myocardial segments. Scar imaging with an ultrasound multipulse scheme (eScar) has been preliminarily validated in prior studies.

Objective

To assess whether scar burden, as detected by eScar, is associated with implantable cardioverter-defibrillator (ICD) shocks in post-MI patients.

Methods

We retrospectively selected 50 post-MI patients with an ejection fraction <35% who received an ICD for primary prevention and subsequently had at least one appropriate shock (cases). These were compared with 50 post-MI patients, matched for clinical variables and ejection fraction, who never experienced an appropriate defibrillator shock (controls). Subjects were assessed with the eScar technique at the time of implantation or during follow-up.

Results

An eScar was present in ≥1 segment in 40 of 50 (80%) cases vs 26 of 50 (52%) controls and was associated with appropriate ICD shocks (P = .004). Receiver operating characteristic curve analysis, using a threshold of ≥3 segments by eScar, showed an area under the curve (AUC) of 0.715. On models including clinical and echocardiographic variables, eScar remained significantly associated with ICD shocks (P = .050 or P = .033 depending on the model). Adding eScar to a multivariate logistic regression model including indexed left ventricular end-systolic volume led to an increase in AUC from 0.734 to 0.782 (P = .049), while substituting indexed left ventricular end-diastolic volume for indexed left ventricular end-systolic volume resulted in a nonsignificant increase in AUC from 0.747 to 0.785 (P = .098).

Conclusions

Presence and extent of eScar were independently associated with appropriate ICD shocks in this study of patients with prior MI and reduced ejection fraction. However, the addition of eScar assessment to the clinical multivariable model that included also indexed left ventricular end-diastolic volume did not provide significant incremental value.

Section snippets

Study Design and Population

This study is a single-center retrospective case-control study, performed at the Parma University Medical Center, Parma, Italy.

We evaluated all patients (n = 268) who underwent ICD implantation for primary prevention of SCD because of severely reduced left ventricular (LV) systolic function (LV ejection fraction [LVEF] < 35%) after an angiographically confirmed MI between October 2008 and October 2017.

The inclusion criteria were (1) history of ischemic heart disease with at least one prior MI,

Results

Among the 50 subjects receiving at least one appropriate ICD shock, 34 (68%) had sustained ventricular tachycardia, while 16 (32%) were shocked for ventricular fibrillation. Mean time (±SD) between the index echocardiogram to either ICD discharge or final uneventful follow-up was 1,483.5 ± 919.5 days for cases and 1,595.9 ± 836.3 days for controls (P = .526).

Table 1 compares demographics, risk factors, medical history, and medical therapy data between the 50 cases and the 50 matched controls.

Discussion

The main finding of this study is that the presence and extent of myocardial scar, as determined by the eScar technique, is independently associated with appropriate ICD shocks in post-MI patients. Previous studies have also identified the presence and extent of myocardial scar as risk markers for SCD or ICD shocks, in patients with ischemic as well as in patients with nonischemic cardiomyopathy.1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,20, 21, 22 However, most of these have employed CMR, which has

Conclusion

In this study a 2D multipulse echocardiography technique was used to detect the presence and extent of “eScar,” a surrogate ultrasound finding for myocardial scar. The extent of this eScar finding was associated with appropriate ICD discharges independent of demographic, clinical, and other echocardiography variables. In our study we could not demonstrate an incremental improvement in the association of the eScar with ICD discharge above that provided by clinical models comprising LVEDV.

References (22)

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      Citation Excerpt :

      Nevertheless, myocardial scar assessment by echocardiography is valuable and has been correlated to clinical outcomes. Gaibazzi et al.,30 using a pulse cancellation technique to detect scar, reported that the presence and extent of scar was significantly correlated with implantable cardioverter defibrillator therapies in a cohort of 50 patients after MI. Wang et al.31 found that the presence of myocardial scar affects LV diastolic function and adds incrementally to its association with mortality.

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    Conflicts of Interest: None.

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