Initial EKG Research Articles

790-4 The Prognostic Importance of Anterior ST-Segment Depression in Inferior Myocardial Infarctions: Results in 16,185 Patients

The prognostic significance of anterior ST-segment depression (ST DEP) in patients with an acute inferior MI remains controversial, in part because of limited sample size in previous studies. Using data from the GUSTO trial, we investigated the clinical outcomes of 16,185 patients with inferior MI. 12,019(74.3%) of these patients had at least 0.1 mV ST DEP in leads Vl–V3 on initial EKG as determined by Core Lab review. Patients with anterior ST DEP were older and more likely to be female or have a history of smoking. Patients with anterior ST DEP also had significantly higher peak CPK levels Imean 2,520 vs. 1,216 ng/dL, p < 0.01). Of the 7,455 (46%) patients with an inferior MI who received cardiac catheterization, those with anterior ST DEP had similar rates of LAD disease (24.8% vs 24.9%, p > 0.5), and multivessel disease (31.1% vs. 29.4%, P > 0.25), but a significantly lower mean LVejection fraction (53.8% vs. 56.4%, p < 0.01) compared with those without ST DEP. In-hospital complications and 3D-day mortality results as a function of the sum of anterior ST DEP are displayed below: Sum of Anterior % %2°–3° % %30-day ST DEP (mV) Killip ≥ 3 * AV Block * Reinfarction Mortality * None (n = 4,166) 3.9 9.6 3.4 3.2 0.1-0.2 (n = 4,449) 5.3 11.2 4.4 3.6 03-0.4 (n = 3,328) 5.6 11.9 4.3 4.4 ≥ 0.5 In = 4,244) 9.2 14.5 4.6 6.6 * p < 0.001 comparing inferior MI patients with and without anterior STDEP Among inferior MI patients, the presence of anterior STsegment depression predicted larger infarctions and predicted worse postMI LV function. Although the overall rates of complications and mortality were low in inferior AMI patients, these risks increased substantially with increasing anterior ST depression. Thus, the magnitude of anterior ST de-pression may be applied to stratify risk in inferior MI patients.

Evaluation and Outcome of Patients with Syncope

We studied 433 patients with syncope to derive insights into the diagnostic evaluation and outcome of patients with this common problem. This study shows that the etiology of syncope was not found in approximately 41% of patients. When a cause of syncope was determined, it was most frequently established on the basis of initial history, physical examination and an electrocardiogram (EKG). Furthermore, many of the other entities (e.g., aortic stenosis, subclavian steal) were suggested by findings on the history and physical examinations that required directed diagnostic testing. Initial EKG was abnormal in 50% of patients but led to a cause of syncope infrequently (less than 7%). Prolonged electrocardiographic monitoring, which has assumed a central role in the evaluation of syncope, led to a specific cause in only 22% of patients. Other tests were less often helpful in assigning a cause of syncope. At 5 years, the mortality of 50.5% in patients with a cardiac cause of syncope was significantly higher than the 30% mortality in patients with a noncardiac cause or 24.1% in patients with an unknown cause. At 5 years, a mortality of 50.5% in patients with a cardiac cause of syncope was noted. There were 54 actual deaths in this group as compared to 10.7 expected deaths based on 1980-86 mortality data from Allegheny County, PA (standardized mortality ratio = 5.02). At 5 years, a 33.1% incidence of sudden death was noted in patients with cardiac cause of syncope, as compared with 4.9% in patients with a noncardiac cause and 8.5% in patients with an unknown cause. Mortality and sudden death remained significant for the first 3 years after which the survival curves were parallel. A cardiac cause of syncope was an independent predictor of sudden death and mortality. Recurrences were common but were not associated with an increased risk of mortality or sudden death. Major vascular events were also more frequent in patients with cardiac causes of syncope. The results of this study will be helpful in designing future studies to evaluate the usefulness of newer diagnostic techniques. Furthermore, short- and long-term outcome data will be useful in planning intervention strategies in these patients.

Electrocardiographic characteristics in EMD

Little has been written concerning the initial electrocardiographic (EKG) characteristics and/or changes which occur as the result of treatment in the electromechanical dissociation (EMD) patient. The purpose of this retrospective study was to determine predictive indicators of successful resuscitation in EMD by evaluating various EKG parameters. During 72 months, ending December 31st, 1985, there were 503 non-poisoned, prehospital adult cardiac arrest patients whose initial rhythm was EMD. All patients had their initial prehospital EKG rhythm strip evaluated for rhythm type, rate, the presence of P waves, QT interval and QRS interval. In successfully resuscitated patients, the prehospital initial rhythm analysis and the rhythm analysis on emergency department presentation were compared. Successfully resuscitated patients presenting with EMD had significantly faster initial rates, higher incidences of P waves and average QRS and QT intervals shorter than patients not responding to therapy. Furthermore, successfully resuscitated patients had significantly increased heart rates, developed new onset of P waves, and shortened QT intervals in response to treatment. Successfully resuscitated and save patients had average initial and final QRS complex lengths within normal limits. Organized atrial activity on the initial EKG was also correlated with successful resuscitation. No patient with an initial EKG rhythm of second or third degree AV block survived to hospital discharge. No patient who presented to the emergency department with atrial fibrillation survived to hospital discharge. Similarly, supraventricular tachycaydia following resuscitative efforts appeared to be associated with a negative outcome. Rate normalization following treatment was correlated with save rate. Wide complex rhythms without atrial activity were most highly associated with unsuccessful resuscitation. We believe these observed electrocardiographic characteristics and/or changes in response to treatment may have predictive value in evaluating patients with EMD.