Early risk stratification of ST-elevation myocardial infarction (STEMI) and immediate intervention is necessary to avoid morbidity/motrality. Pre-infarction syndrome (PIS), defined by initial electrocardiogram (ECG) has been shown to be associated with less myocardial damage with thrombolytic therapy, but has never been investigated in the era of percutaneous coronary interventions. We hypothesized that the PIS may have additional value to estimate acute-phase ejection fraction (APEF) and contribute to early recognition of high-risk patients with STEMI.
We included all the patients of STEMI who visited our institution from June 2007 to September 2008. Pathological Q waves were defined as > 1/3 of the height of R waves or duration > 0.04ms. If both negative portion in T waves and pathological Q-waves were absent in lead with the most ST-elevation, the condition was determined as PIS. APEF was obtained by left-ventriculogram, or if not performed, by echocardiogram within 72 hours from presentation. Factors that may affect APEF, including age, gender, location (inferior or anterior), risk factors, history of ischemic heart disease and past interventions, onset-to-door time, door-to-baloon/needle time, initial and peak troponin, treatment modality and successfulness, usage of medication, method of measuring EF, were obtained. Multiple regression analysis by stepwise method was performed to include/exclude variables that affect APEF.
Multivariable ananysis yielded the following formula (A=1 if inferior MI, A = 0 if anterior MI; B = peak troponin; C = 1 if PIS, C = 0 if not PIS); EF(%) = 14.36A −0.034B +7.86C +58.35 (R = 0.69; 95% confidence interval of coefficient for C, −14 to −1.4; p = 0.017). None of the other variables was significantly associated with the APEF. The association between PIS and APEF was independent from other parameters.
PIS was significantly and independently associated with better acute-phase EF in patients with STEMI, suggesting less myocardium damage on arrival.
Recognizing PIS by initial ECG contributes to early risk stratification in patients with STEMI.
Yuichi Shimada, No Financial Disclosure Information; No Product/Research Disclosure Information