Despite reports of patients with resuscitated sudden cardiac arrest (rSCA) receiving acute cardiac catheterization, the efficacy of this strategy is largely unknown. We hypothesized that acute cardiac catheterization of patients with rSCA would improve survival to hospital discharge. A retrospective cohort of 240 patients with out-of-hospital rSCA caused by ventricular tachycardia or fibrillation was identified from 11 institutions in Seattle, Washington from 1999 through 2002. Patients were grouped into those receiving acute catheterization within 6 hours (≤6-hour group, n = 61) and those with deferred catheterization at >6 hours or no catheterization during the index hospitalization (>6-hour group, n = 179). Attention was directed to survival to hospital discharge, neurologic status, extent of coronary artery disease, presenting electrocardiographic findings, and symptoms before arrest. Propensity-score methods were used to adjust for the likelihood of receiving acute catheterization. Survival was greater in patients who underwent acute catheterization (72% in the ≤6-hour group vs 49% in the >6-hour group, p = 0.001). Percutaneous coronary intervention was performed in 38 of 61 patients (62%) in the ≤6-hour group and 13 of 170 patients (7%) in the >6-hour group (p <0.0001). Neurologic status was similar in the 2 groups. A significantly larger percentage of patients in the acute catheterization group had symptoms before cardiac arrest and had ST-segment elevation on electrocardiogram after resuscitation. Age, bystander cardiopulmonary resuscitation, daytime presentation, history of percutaneous coronary intervention or stroke, and acute ST-segment elevation were positively associated with receiving cardiac catheterization. In conclusion, in this series of patients who sustained out-of-hospital cardiac arrest, acute catheterization (<6 hours of presentation) was associated with improved survival.
We hypothesized that acute cardiac catheterization of patients with resuscitated sudden cardiac arrest (rSCA) would improve survival to hospital discharge. To test this hypothesis we performed a retrospective analysis on all patients with rSCA who were admitted to Seattle area hospitals during a period before the widespread use of therapeutic hypothermia. We chose this earlier time frame because therapeutic hypothermia has been shown to increase survival in rSCA, which may confound the interpretation of the results. Survival and neurologic outcomes in patients with rSCA who underwent early coronary angiography (≤6 hours) were compared to control patients who did not undergo coronary angiography or underwent angiography >6 hours after admission to the hospital.
Methods
This study included 240 consecutive patients who were resuscitated from out-of-hospital rSCA with ventricular fibrillation or tachycardia as the first identified rhythm. At successful resuscitation the patients were transported to 1 of 11 receiving hospitals, all but 1 with cardiac catheterization facilities. The incidents occurred from January 6, 1999 through December 15, 2002, a period before widespread use of therapeutic hypothermia for resuscitated ventricular fibrillation patients in Seattle area hospitals.
The Seattle fire department’s emergency medical services system, Medic One, has been previously described. Variables collected for this study came from the standard Medic One screening and hospital forms and medical records review performed by the first author (J.A.S.). Demographic variables, medical history variables, and variables describing the circumstances of cardiac arrest were obtained from the screening or hospital forms. Medical records review was performed to obtain details of cardiac catheterization including timing, presence of ST-segment elevation (increase 1 mm in 2 contiguous leads), and location and extent of significant coronary artery lesions. The major independent variable of interest was whether the patient underwent cardiac catheterization ≤6 hours after hospital admission. Those who did were included in the acute cardiac catheterization or ≤6-hour group, whereas those who underwent the procedure at a later time or did not receive the procedure were included in the >6-hour group.
Outcome variables obtained from the Medic One hospital forms included use of percutaneous coronary intervention (PCI), days hospitalized, hospital discharge status, and neurologic status. The primary outcome measurement, hospital discharge status, was recorded on the hospital form and was defined as dead or alive. Neurologic status was determined from information in the medical records and was categorized as full recovery, mild impairment, severe impairment, or comatose.
Comparisons of characteristics of the ≤6-hour and >6-hour groups were performed using the chi-square statistic for categorical variables and 2-sample t test for continuous measurements. The decision to use acute cardiac catheterization is complex and difficult to adjust for in multivariate statistical modeling. Propensity analysis was used to control for the likelihood of a patient to undergo acute cardiac catheterization. The following variables were considered for the propensity score, with backward stepwise logistic regression used to select the final model: age, gender, bystander cardiopulmonary resuscitation, witnessed arrest, current smoking, daytime presentation, history of smoking, myocardial infarction, congestive heart failure, hypertension, previous PCI, coronary artery bypass graft surgery, diabetes, stroke, neurologic disease, lung disease, and ST-segment elevation on electrocardiogram (ECG). The propensity score was categorized according to terciles, and within each tercile survival rates in the ≤6-hour and >6-hour groups were compared.
Results
Of the 240 patients, 25% underwent acute cardiac catheterization (≤6-hour group) and 75% did not (>6-hour group). In the >6-hour group, 43 underwent cardiac catheterization 6 hours after hospital admission and 136 did not undergo this procedure. Patients in the ≤6-hour group were 3 years younger and more often men, although the racial distribution was similar in the 2 groups ( Table 1 ). With respect to medical histories, patients in the ≤6-hour group less often had previously recognized coronary artery disease, cardiomyopathy, arrhythmias, heart failure, or stroke and were more likely to have had a history of smoking.
| Variable | ≤6-Hour Group (n = 61) | >6-Hour or No Catheterization Group (n = 179) | p Value |
|---|---|---|---|
| Age (years) | 64 ± 13 | 67 ± 17 | 0.25 |
| Women | 8 (13%) | 56 (31%) | 0.006 |
| Race | 0.58 | ||
| White | 47 (77%) | 142 (79%) | |
| Black | 6 (10%) | 17 (10%) | |
| Native-American | 1 (2%) | 1 (1%) | |
| Asian | 4 (7%) | 11 (6%) | |
| Other | 1 (2%) | 0 (0%) | |
| Unknown | 2 (3%) | 8 (4%) | |
| Coronary artery disease | 14 (23%) | 78 (45%) | 0.002 |
| Valvular heart disease | 4 (7%) | 19 (11%) | 0.32 |
| Cardiomyopathy | 5 (8%) | 43 (25%) | 0.006 |
| Myocardial infarction | 7 (12%) | 43 (25%) | 0.032 |
| Congestive heart failure | 5 (8%) | 54 (31%) | <0.0001 |
| Arrhythmia | 8 (13%) | 62 (36%) | 0.001 |
| Hypertension | 29 (48%) | 80 (46%) | 0.78 |
| Hyperlipidemia | 15 (25%) | 57 (33%) | 0.25 |
| Coronary angioplasty | 4 (7%) | 17 (10%) | 0.46 |
| Coronary artery bypass grafting | 5 (8%) | 29 (17%) | 0.11 |
| Diabetes mellitus | 8 (13%) | 36 (21%) | 0.20 |
| Stroke | 2 (3%) | 30 (17%) | 0.007 |
| Renal failure | 1 (2%) | 14 (8%) | 0.22 |
| Smoker | 35 (58%) | 69 (40%) | 0.013 |
Regarding the circumstances of arrest, a slightly larger proportion in the ≤6-hour group had acute symptoms before cardiac arrest. Otherwise, the distributions of initial rhythm, bystander cardiopulmonary resuscitation, witnessed arrest, and daytime presentation to the hospital were not statistically different ( Table 2 ). As expected, a larger percentage of the ≤6-hour group had ST-segment elevation on admission ECG (46 of 61, 75%, vs 36 of 179, 20%, p <0.0001). In contrast, in those undergoing cardiac catheterization, there were no differences in left main coronary artery lesions with ≥50% diameter narrowing (5% vs 2%, p = 0.48), proximal left anterior descending artery lesions with ≥70% diameter narrowing (28% vs 20%, p = 0.31), or 3-vessel disease (44% vs 35%, p = 0.35).
| Variable | ≤6-Hour Group (n = 61) | >6-Hour or No Catheterization Group (n = 179) | p Value |
|---|---|---|---|
| Ventricular fibrillation initial rhythm | 61 (100%) | 173 (97%) | 0.15 |
| Acute symptoms before cardiac arrest | 23 (38%) | 42 (24%) | 0.024 |
| Bystander cardiopulmonary resuscitation | 30 (49%) | 90 (50%) | 0.88 |
| Witnessed arrest | 53 (87%) | 147 (82%) | 0.39 |
| Daytime presentation | 49 (82%) | 125 (70%) | 0.12 |
Selected outcomes in the 2 groups are listed in Table 3 . A key finding was that a much larger proportion of patients in the ≤6-hour group were discharged alive from the hospital. Length of hospital stay was similar in the 2 groups as was the percentage of patients who awakened. Neurologic status at discharge was also similar in the 2 groups; almost 80% of survivors in each group had full recovery or mild impairment. More than 60% of the ≤6-hour group underwent PCI, whereas only 30% of those who underwent nonacute cardiac catheterization did.
| Variable | ≤6-Hour Group (n = 61) | >6-Hour or No Catheterization Group (n = 179) | p Value |
|---|---|---|---|
| Discharged alive | 44 (72%) | 87 (49%) | 0.001 |
| Days hospitalized | 9.1 ± 6.0 | 9.8 ± 21.7 | 0.81 |
| Percutaneous coronary intervention | 38 (62%) | 13 (7%) | <0.0001 |
| Awakened | 40/60 (67%) | 93/174 (53%) | 0.08 |
| Best neurologic status | 0.30 | ||
| Full recovery | 18/43 (42%) | 47/86 (55%) | |
| Mild impairment | 16/43 (37%) | 19/86 (22%) | |
| Severe impairment | 4/43 (9%) | 11/86 (13%) | |
| Comatose | 5/43 (12%) | 9/86 (10%) |
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