In patients with acute myocardial infarction, reocclusion after achievement of coronary reperfusion by thrombolytic therapy using urokinase (UK) or tissue plasminogen activator (tPA) has become a problem. The causes of reocclusion may include rethrombosis as well as activation of platelets and coagulation factors by thrombolytic agents. To elucidate the mechanism of reocclusion involved, thrombin generation was measured. Coagulation of platelet-rich plasma was induced by CaCl_2. Each sample was reacted with S-2238 to determine the thrombin generation. UK or tPA was added to this system and the thrombin generation was assessed. The clotting time was shortened by UK and tPA when compared with control. Thrombin generation was increased by UK and tPA. Stimulation of thrombin generation by thrombolytic agents may contribute to reocclusion.
The criteria usually used for the diagnosis of inferoposterior myocardial infarction (MI) are an R/S ratio ≥1.0 in lead V1 or V2 and electro-cardiographic (ECG) findings indicative of an inferior MI. However, no studies have investigated whether the amplitude of the QRS complex in the right precordial leads obtained before the onset of MI (baseline ECGs) affects the ECG-based diagnosis of inferoposterior MI. We studied 78 patients who had had ECGs recorded within 6 months before MI, 53 with an inferior MI and 25 with an inferoposterior MI. The two groups were compared in relation to ECG findings and regional wall motion shown by two-dimensional echocardiography. The baseline R-wave amplitude and R/S ratio in leads V1 and V2 were significantly greater in patients with inferoposterior MI than in those with inferior MI. Two-dimensional echocardiography revealed abnormal posterior wall motion in 44% of patients with inferoposterior MI but in 2% of the patients with inferior MI. When abnormal posterior wall motion was used to define posterior MI, the conventional ECG criteria for inferoposterior MI had a sensitivity of 92%, a specificity of 78%, a positive predictive value of 44%, and an accuracy of 81%. Using new diagnostic criteria in which inferoposterior MI was diagnosed by the difference between the R/S ratios in lead V1 from the baseline and post-infarction ECGs ≥0.3 and findings indicative of inferior MI, the sensitivity was 83%, the specificity was 91%, the positive predictive value was 63%, and the accuracy was 90%. Conventional diagnostic criteria for inferoposterior MI are affected by variability in the amplitude of the QRS complex in the right chest leads on the baseline ECG. Using the baseline ECG, we established new criteria with higher accuracy for diagnosing inferoposterior MI.
Cardiogenic shock in the setting of an acute myocardial infarction (MI) with left ventricular (LV) failure is associated with an extensive infarct and a poor prognosis. It also occurs due to hemodynamic deterioration from severe right ventricular (RV) dysfunction in RVMI, and adversely affects the prognosis of acute inferior MI. We evaluated the outcomes of patients with acute inferior MI and cardiogenic shock with respect to the presence or absence of RVMI. Subjects consisted of 504 consecutive patients with acute inferior MI. On admission, 159 of the 504 patients were diagnosed as having an RVMI. Of these, 69 developed cardiogenic shock in the acute phase (RVMI (+)/shock (+)), while 90 did not (RVMI (+)/shock (-)). Of the 345 patients without RVMI, 99 developed cardiogenic shock in the acute phase (RVMI (-)/shock (+)), while 246 did not (RVMI (-)/shock (-)). Compared with RVMI (+)/shock (+) patients, patients in the RVMI (-)/shock (+) group had a significantly increased LV dimension (p<0.01) and total wall motion index (p<0.01) and significantly reduced values for LV ejection fraction, RV dimension, right atrial pressure, and the rate of primary coronary angioplasty (all p<0.05). RVMI (-)/shock (+) patients exhibited increased in-hospital mortality (p<0.01) and reduced long-term survival (p<0.01) compared to the RVMI (+)/shock (+) group. Multiple logistic-regression analysis revealed cardiogenic shock, but not RVMI, to be a significant, independent marker for the prediction of long-term prognosis (odds ratio, 3.57 ; 95% confidence interval 2.05-6.22 ;p<0.01). In acute inferior MI, cardiogenic shock is an important predictor of worse in-hospital and long-term outcomes. Development of cardiogenic shock following acute inferior MI is associated with a poor prognosis, even in the absence of RVMI.