Sgarbossa criteria, AMI in LBBB and ventricular pacing

LBBB에서 급성 심근경색을 진단하는 기준으로 Sgarbossa criteria가 있습니다.

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Sgarbossa criteria

A large, historic trial of thrombolytic therapy for acute MI (GUSTO-1) provided an opportunity to revisit the issue of the electrocardiographic diagnosis of evolving acute MI in the presence of LBBB. Among 26,003 North American patients who had a myocardial infarction confirmed by enzyme studies, 131 (0.5 percent) had LBBB. A scoring system, often called the Sgarbossa criteria, was developed from the coefficients assigned by a logistic model for each independent criterion, on a scale of 0 to 5.

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LBBB에서 어떤 leads에서 ST 상승이 1 mm 이상 있으면 Sgarbossa criteria A에 해당하고, V1-V3에서 ST depression이 1 mm 이상 있으면 Sgarbossa B에 해당하며, 이 두 개의 기준은 LBBB에서 AMI 진단에 특이적입니다(A가 B보다 더 특이적). Sgarbossa criteria C는 특이적이지 않아 revised Sgarbossa criteria C가 제안되었고 S파의 길이에 대한 STE 비율이 25 %이상이면 양성이고 원래 기준보다 더 정확합니다.

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The three ECG criteria with an independent value in the diagnosis of acute infarction and the score for each were:

● ST segment elevation of 1 mm or more that is in the same direction (concordant) as the QRS complex in any lead: score 5.

● ST segment depression of 1 mm or more in any lead from V1 to V3: score 3.

● ST segment elevation of 5 mm or more that is discordant with the QRS complex (ie, associated with a QS or rS complex): score 2.

However, prominent J point elevations may occur in V1-V2 solely due to left ventricular hypertrophy or in other settings. Therefore, a ratio (expressed in absolute units) in any relevant lead of the amplitude of the ST-elevation lead divided by the S wave amplitude in that lead that equals or exceeds 0.25 has been proposed as having greater accuracy than the original (not normalized) Sgarbossa criterion. A higher ratio indicates relatively greater ST elevation. The diagnostic superiority of this modified (STE/S wave) criterion as compared with the original "Sgarbossa rule #3" was supported by the findings of a retrospective case-control study.

A Sgarbossa score of ≥3 was highly specific (ie, few false positives) but much less sensitive (36 percent) in the validation sample in the original report. Similar findings were noted in a subsequent meta-analysis of 10 studies of 1614 patients in which a Sgarbossa score of ≥3 had a sensitivity of 20 percent and a specificity of 98 percent. The sensitivity may increase if serial or previous ECGs are available or if the modified criteria (including STE/S wave ratio described above) are used.

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이 Sgarbossa criteria는 pacemaker ECG에서 AMI 진단에 이용됩니다. 그러나 pacemake의 경우에는 Sgarbossa criteria C가 가장 특이적입니다.

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Ventricular pacing

A similar problem is the diagnosis of an acute MI in the presence of a ventricular paced rhythm, which is usually associated with a left bundle branch block pattern. Thirty-two patients in the GUSTO-1 trial (0.1 percent of enrolled patients) had a ventricular paced rhythm. The only ECG criterion with a high specificity and statistical significance for the diagnosis of an acute MI was ST segment elevation ≥5 mm in leads with a negative QRS complex.

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Two other criteria with acceptable specificity were:

● ST elevation ≥1 mm in leads with concordant QRS polarity

● ST depression ≥1 mm in leads V1, V2, or, V3

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REF. UpToDate 2020.01.31

https://ecgweekly.com/2020/01/amal-mattus-ecg-case-of-the-week-january-27-2020/