LBBB에서 AMI 진단, ECG

LBBB에서 AMI 진단

​

​

정상 LBBB

​

전제

1. LBBB에서 ST와 T파는 discordant direction입니다.

2. Serial ECGs가 dynamic ST change를 보이면 ischemia가 진행 중임을 나타냅니다.

...ischemia, infarction etc.

3. 원래는 없었는데 새로운 LBBB는 항상 병적인 것이고 심근경색의 징후일 수 있습니다.

​

​

LBBB 환자에서 심근경색을 진단하는 original Sgarbossa Criteria는 다음과 같습니다.

편의상 A, B, C라고 할 때, A와 B는 심근경색에 특이적입니다. 3점 이상일 때 특이적인데 어느 leads에서라도 ST 상승이 1 mm 이상이거나 V1-V3에서 ST 하강이 1 mm 이상인 경우입니다.

A. Concordant ST elevation > 1mm in leads with a positive QRS complex (score 5)

B. Concordant ST depression > 1 mm in V1-V3 (score 3)

C. Excessively discordant ST elevation > 5 mm in leads with a -ve QRS complex (score 2).

​

C에 해당하는 경우인 어느 leads에서라도 > 5 mm 상승인 것은 특이도가 떨어져 modified Sgarbossa Criteria가 제안되었고 ST deviations > 5 mm 대신 선행하는 S파에 대한 ST 상승이 > 25%인 것으로 정의하였습니다.

​

Modified Sgarbossa Criteria:

A. ≥ 1 lead with ≥1 mm of concordant ST elevation

B. ≥ 1 lead of V1-V3 with ≥ 1 mm of concordant ST depression

C. ≥ 1 lead anywhere with ≥ 1 mm STE and proportionally excessive discordant STE, as defined by ≥ 25% of the depth of the preceding S-wave.

​

There is 1mm concordant ST elevation in aVL (= 5 points)

​

​

There is concordant ST depression in V2-5 (= Sgarbossa positive).

​

There is 1mm concordant ST elevation in II, III, aVF (= 5 points)

​

​

There is 1mm concordant ST elevation in aVL, V4-6 (= 5 points)

​

​

There is 1mm concordant ST elevation in aVL (= 5 points)

There is concordant ST depression in V1-3 (= Sgarbossa positive).

​

​

There is 1mm concordant ST elevation in aVL, V5-V6 (= 5 points)

​

​

There is 1mm concordant ST elevation in I, aVL, V5 (= 5 points)

​

There is concordant ST depression in V1-3 (= Sgarbossa positive).

​

​

There is concordant ST depression in V3 (= Sgarbossa positive).

​

​

There is concordant ST depression in V3 (= Sgarbossa positive).

​

There is 1mm concordant ST elevation in I, aVL (= 5 points)

There is concordant ST depression in V3 (= Sgarbossa positive).

​

≥ 25% of the depth of the preceding S-wave : Revised Sgarbossa criteria

​

≥ 25% of the depth of the preceding S-wave : : Revised Sgarbossa criteria

​

​

​

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.

​

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.

In addition to their utility in diagnosis, the Sgarbossa criteria (and their validated modifications) may also predict prognosis in patients with acute MI.

​

REF.

UpToDate 2019.09.27

https://ecgweekly.com/2019/09/amal-mattus-ecg-case-of-the-week-september-23-2019/