Acute myocardial infarction complicated by shock: outcome analysis based on initial electrocardiogram.

OBJECTIVES

To assess the relation between initial ECG findings, presence of risk factors, coronary angiography findings, and clinical outcomes in patients with acute myocardial infarction complicated by cardiogenic shock (CS).

DESIGN

Data from a total of 5572 acute myocardial infarction patients admitted to the four tertiary hospitals during a period of 3 years were analyzed. CS on admission was present in 358 patients (6.4%). They were divided into four groups based on the admission ECG: ST-segment elevation (STEMI), ST-segment depression (STDMI), bundle branch block (BBBMI), and other ECG acute myocardial infarction.

RESULTS

CS developed most frequently among BBBMI patients (in 12.1% of all BBBMIs, p < 0.001 vs. STEMI), followed by STEMI (6.7%), STDMI (4.4%), and other ECG acute myocardial infarction (2.3%). The risk of CS development was similar in patients with left bundle branch block (LBBB) (13.3%) and right bundle branch block (RBBB) (11.2%). The one-year mortality was highest among RBBBMI patients (66.7%, p < 0.001), followed by LBBBMI (48.6%), other ECG (47.1%), STEMI (41.7%), and STDMI patients (38.1%).

CONCLUSIONS

RBBB on admission ECG is associated with the highest risk of CS development, frequent left main coronary artery affection, and unsuccessful revascularization. It is also an independent predictor of one-year mortality.