Immediate Coronary Angiography in Survivors of Out-of-Hospital Cardiac Arrest

ABSTRACT & COMMENTARY

Synopsis: Immediate coronary angiography with angioplasty of any recent coronary artery occlusions is feasible, safe, and appears to improve long-term outcome after resuscitated cardiac arrest.

Source: Spaulding CM, et al. N Engl J Med 1997; 336:1629-1633.

In this paper, spaulding and colleagues report on the results of a strategy that employed immediate coronary angiography and, where feasible, angioplasty of new coronary occlusions in resuscitated victims of out-of-hospital cardiac arrest. Four emergency response units from Paris participated. During the study, these units responded to 1762 cases of suspected cardiac arrest. Resuscitation was attempted in 910 patients, with initial restoration of stable pulse and blood pressure in 312. Recurrent arrest during transport resulted in only 186 patients arriving at the hospital alive. Patients with obvious noncardiac causes for cardiac arrest and patients either younger than 30 or older than 75 were excluded. The remaining 85 patients were transferred to a single center for cardiac catheterization. One of these patients was also excluded when diffuse vascular disease made catheterization impossible.

Twenty-four of the 84 patients (28%) had no or only minor coronary artery disease. Recent coronary occlusions were noted in 40 of the 60 (67%) patients with coronary disease. Eighteen of the remaining 20 had complex or irregular lesions similar to those associated with unstable angina. Thirty-seven of the patients with recent coronary occlusions underwent attempted balloon angioplasty. The procedure was successful in 28 of 37 (76%).

Multivariate logistic regression was used to test for clinical or electrocardiographic predictors of acute coronary occlusion. ST elevation and chest pain before arrest were the only predictors identified.

Thirty-two of the 85 original patients survived to hospital discharge. Two factors were identified as predictive of survival: absence of need for inotropic drug support and successful coronary angioplasty. Survival after discharge was excellent. Only a few patients received specific antiarrhythmic therapy. The three deaths seen over a median of 13 months follow-up were not due to recurrent cardiac arrest. Spaulding et al conclude that immediate coronary angiography with angioplasty of any recent coronary artery occlusions is feasible, safe, and appears to improve long-term outcome after resuscitated cardiac arrest.

COMMENT BY JOHN P. DiMARCO, MD, PhD

The pathophysiology of out-of-hospital cardiac arrest remains controversial. Some authors have argued strongly that acute ischemia is the most common mechanism responsible for sudden death, while others have focused on scar-related ventricular tachycardia as the most important precursor to ventricular fibrillation. The data presented here, showing that 67% of the patients with coronary disease had acute coronary occlusions, and an additional 28% had potentially unstable lesions, argue strongly for the ischemia hypothesis.

As shown by Spaulding et al, a clinical history of chest pain and electrocardiographic markers of acute ischemia were both present in only a minority of patients, and some patients with neither of these findings had recent total coronary occlusions. Therefore, an aggressive strategy that uses early coronary angiography and angioplasty would seem justified if the prospects of long-term survival are to be improved.

Several factors must be considered before we fully accept the ischemia hypothesis. It must be remembered that the 85 patients in this report were selected out of a much larger pool of 1762 cardiac arrest victims. As in other series, the majority of cardiac arrest victims died in the field, and the survivors who were eventually studied may not be representative of the entire group. Even if only those who reached the hospital alive in this study are considered, more than half of such patients were excluded from catheterization due to age or another unspecified cause. Thus, the findings here may not be relevant to all, or even the majority of, patients with cardiac arrest.

Other reports have suggested a lower prevalence of acute ischemia in patients with sudden death. Marcus et al (Am J Cardiol 1988;61:8-15) and Greene et al (Am J Cardiol 1989;63:1-6) believed that ischemia preceded sudden death in 58% and 40% of their cases, respectively. However, those authors made a diagnosis of acute ischemia on the basis of history or ECG findings. In the report by Spalding et al, nine of 40 patients with acute occlusions had neither chest pain nor ST elevation on their ECG. Thus, the data in the current study argue that clinical history and routine ECG findings underestimate the significance of acute ischemia as a trigger for sudden death.

It is, however, hard to reconcile the data in this study with three observations from earlier studies. Other historical studies have indicated a substantial risk of recurrent ventricular tachycardia and ventricular fibrillation in cardiac arrest survivors (N Engl J Med 1988;318:19-24). Studies reporting Holter monitor findings in cardiac arrest victims have only rarely described ECG signs of ischemia preceding the event (Am Heart J 1989;117:151-159). Finally, experience with cardiac arrest victims who have received ICDs has shown frequent recurrence of arrhythmia without evidence of acute coronary occlusion (Circulation 1993;88:1083-1092).

This paper will not settle the "ischemia vs. primary arrhythmia" controversy. Both factors are likely to be important. In populations with coronary artery disease and previously completely normal ventricular function, sudden death is more likely to be an ischemic event. In patients with prior infarction, the situation is undoubtedly more complex, with both paroxysmal arrhythmia and acute ischemia important factors.