What is the clinical evidence from this study?

Study design: Observational. Population: Suspected or known coronary artery disease (n=81). Intervention: Core lab interpretation of stress echocardiography vs. Local site interpretation. Primary outcome: Concordance between site and core lab interpretations of the degree of left ventricular myocardial ischemia (K = 0.635).

December 1, 2015Open Access

The value of core lab stress echocardiography interpretations: observations from the ISCHEMIA Trial

Key Result

Site stress echocardiography interpretations were largely concordant with core lab interpretations (81% agreement, K=0.635), though sites tended to over-estimate the extent of ischemia in mild cases.

Study Design

Type

Observational (n=81)

Blinding

Blinded to site interpretations

Multicenter

Yes

Structured PICO

Does core lab interpretation of stress echocardiography agree with local site interpretation in patients evaluated for the ISCHEMIA trial?

Population

81 stress echocardiography cases submitted from 41 international sites during the pre-enrollment certification phase of the ISCHEMIA Trial to evaluate interpretation concordance.

Exposure

Core lab interpretation of stress echocardiography

Comparator

Local site interpretation of stress echocardiography

Outcome

Concordance of site and core lab interpretations of ischemia (classified by number of new or worsening segmental LV wall motion abnormalities)surrogate

Main Result

Effect estimate: K = 0.635

Limitations

Lack of access to patient demographic data
Lack of information about the site readers' experience
Inability to assess concordance as a function of coronary anatomy by angiography or CT
Small number of cases using contrast agents
Differences in the numbers of pharmacologic and exercise stress cases
Did not incorporate new technologies such as strain imaging

Abstract

BACKGROUND: Stress echocardiography (SE) is dependent on subjective interpretations. As a prelude to the International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA) Trial, potential sites were required to submit two SE, one with moderate or severe left ventricular (LV) myocardial ischemia and one with mild ischemia. We evaluated the concordance of site and core lab interpretations. METHODS: Eighty-one SE were submitted from 41 international sites. Ischemia was classified by the number of new or worsening segmental LV wall motion abnormalities (WMA): none, mild (1 or 2) or moderate or severe (3 or more) by the sites and the core lab. RESULTS: Core lab classified 6 SE as no ischemia, 35 mild and 40 moderate or greater. There was agreement between the site and core in 66 of 81 total cases (81%, weighted kappa coefficient K =0.635). Agreement was similar for SE type - 24 of 30 exercise (80%, K = 0.571) vs. 41 of 49 pharmacologic (84%, K = 0.685). The agreement between poor or fair image quality (27 of 36 cases, 75%, K = 0.492) was not as good as for the good or excellent image quality cases (39 of 45 cases, 87%, K = 0.755). Differences in concordance were noted for degree of ischemia with the majority of discordant interpretations (87%) occurring in patients with no or mild LV myocardial ischemia. CONCLUSIONS: While site SE interpretations are largely concordant with core lab interpretations, this appears dependent on image quality and the extent of WMA. Thus core lab interpretations remain important in clinical trials where consistency of interpretation across a range of cases is critical. TRIAL REGISTRATION: ClinicalTrials.gov NCT01471522.

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