Despite early revascularization, mortality remains high in patients with ST-segment elevation myocardial infarction (STEMI) complicated by cardiogenic shock. It has been shown that the effect of multivessel disease (MVD) on mortality in patients with STEMI treated with primary percutaneous coronary intervention is mainly caused by the presence of chronic total occlusion (CTO) in a noninfarct-related coronary artery. Whether this association also exists in patients with STEMI with cardiogenic shock is unknown. In our institution, 292 consecutive patients with STEMI complicated by cardiogenic shock were admitted from 1997 to 2005 and treated with primary percutaneous coronary intervention. Patients were classified as having single vessel disease, MVD without CTO, and CTO. Cox regression analysis was used for multivariate analysis. The 1-year mortality rate of patients with single-vessel disease, MVD, and CTO was 31%, 47%, and 63%, respectively. After adjustment for possible confounders, MVD alone was not an independent predictor of 1-year mortality (hazard ratio 1.5, 95% confidence interval 0.98 to 2.3, p = 0.07). In contrast, CTO in a noninfarct-related artery was an independent predictor of 1-year mortality (hazard ratio 2.1, 95% confidence interval 1.5 to 3.1, p <0.01). In conclusion, the presence of CTO in a non–infarct-related artery was an independent predictor of 1-year mortality. In contrast, MVD alone lost its predictive significance after multivariate analysis.
In the setting of primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI), we demonstrated that the effect of multivessel disease (MVD) on mortality is mainly determined by the presence of a chronic total occlusion (CTO) in a noninfarct-related artery (IRA). After an adjustment for possible confounders by multivariate Cox regression analysis, MVD without CTO was not an independent predictor of mortality. In contrast, a CTO in a non-IRA was a strong and independent predictor of both short and long-term mortality. Conde-Vela et al previously reported that CTO in a non-IRA was independently associated with developing cardiogenic shock at admission for STEMI. Currently, no reports are available on the effect of CTO on the clinical outcome in patients with STEMI complicated by cardiogenic shock. We, therefore, studied the effect of MVD with and without CTO in a non-IRA on 1-year mortality in patients with STEMI and cardiogenic shock treated with primary PCI. We hypothesized that the presence of CTO might be a more important predictor of 1-year mortality than the mere presence of MVD.
Methods
The study cohort consisted of all patients with STEMI treated with primary PCI who presented with cardiogenic shock at admission to our institution from January 1997 to March 2005. Patients who developed cardiogenic shock after admission were not included. Acute STEMI was diagnosed when patients had symptoms of acute myocardial infarction lasting 30 minutes to 6 hours, accompanied by an electrocardiogram with ST-segment elevation >1 mm (0.1 mV) in ≥2 contiguous leads. Cardiogenic shock was defined according to the clinical criteria used in the Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock (SHOCK) trial: systolic blood pressure ≤90 mm Hg for ≥30 minutes or vasopressors required to maintain blood pressure >90 mm Hg, evidence of end organ hypoperfusion (eg, urine output <30 ml or cold/diaphoretic extremities or altered mental status), and evidence of elevated filling pressures (eg, pulmonary congestion on examination or chest x-ray). Patients were immediately transported to the catheterization laboratory and underwent immediate angiography with the aim of performing primary PCI. If the coronary anatomy was suitable for PCI, the procedure was performed using standard techniques. All patients were treated with heparin and aspirin before PCI. The treatment of cardiogenic shock was at the discretion of the attending cardiologist and included fluid resuscitation, endotracheal intubation, placement of an intra-aortic balloon pump, and catecholamine administration.
The data from 3,038 consecutive and unselected patients with STEMI treated with primary PCI at our hospital from January 1997 to March 2005 were entered in a dedicated database. The data from the 3,038 patients were checked for consistency and completeness. Of these patients, 292 (9.6%) presented in cardiogenic shock.
The baseline clinical, angiographic, and procedural characteristics were collected prospectively in a dedicated database. On the operator’s on-line assessment during emergency angiography, the patients were categorized as having single-vessel disease, MVD without CTO, or MVD with concurrent CTO. For the purposes of the present study, MVD was defined according to the criteria used in the SHOCK trial: ≥1 stenosis >50% of the coronary lumen diameter in one or more of the noninfarct-related epicardial arteries or left main stenosis ≥50%. CTO was defined as 100% luminal narrowing in a non-IRA before PCI without anterograde flow or with anterograde or retrograde filling through the collateral vessels. Hypercholesterolemia was defined as known according to protocol; follow-up data, including information on cardiac medication, was collected by a written questionnaire sent to all patients after 1 year. Missing or inconsistent data were completed by review of the hospital records and outpatient reports. Finally, information on vital status was obtained from the Dutch national population registry (Statistics Netherlands, Voorburg, The Netherlands) and verified until January 2007.
The baseline characteristics of the study patients, grouped according to the extent of coronary disease, are presented as percentages and counts for dichotomous variables. The chi-square statistic was used to test for differences between proportions. Statistical significance was defined as p <0.05. Cumulative event rates for death were calculated according to the Kaplan-Meier method, and the timing of death was illustrated by Kaplan-Meier plots. Differences between the curves were tested for significance using the log-rank statistic. To study the independent value of MVD with and without CTO in a non-IRA on 1-year mortality, we performed forward stepwise Cox regression multivariate analysis. All significantly different distributed clinical and angiographic covariates were included in the model (age ≥75 years, diabetes, hypercholesterolemia, previous myocardial infarction, β blockers, lipid-lowering drugs, multivessel PCI, thrombosuction, and intra-aortic balloon pump counterpulsation), and known predictors for 1-year mortality (Thrombolysis In Myocardial Infarction flow grade <3 after primary PCI, anterior STEMI). A covariate was included in the model if it influenced the model with p <0.10 using the Wald test and was removed if its significance level exceeded p = 0.15. The assumptions underlying the proportional hazards model (proportional hazards and lack of interaction) were tested and found valid for all covariates included in the model. All calculations were generated using the Statistical Package for Social Sciences, version 15.0, software (SPSS, Chicago, Illinois).
Results
Of the 3,038 patients with STEMI, 292 (9.6%) presented in cardiogenic shock. The 1-year follow-up data were complete for all patients. Of the 292 patients, 161 (55%) had MVD, of whom 92 (32%) had MVD without CTO and 69 (24%) had CTO in a non-IRA. The clinical, baseline, and treatment characteristics are presented in Table 1 . Compared to the patients with single-vessel disease, those with MVD were older and more often had diabetes and hypercholesterolemia on admission. Moreover, in these patients, intra-aortic balloon pump counterpulsation was more frequently used, thrombosuction was less often performed, and lipid-lowering drugs were less often administered. Compared to patients with single-vessel disease and MVD without CTO, those with CTO in a non-IRA significantly more often had had previous myocardial infarction, previous PCI, and previous coronary artery bypass grafting and were more frequently treated with β blockers. In our cohort, multivessel primary PCI was performed in 21 patients (23%) with MVD without CTO and 16 patients (23%) with MVD and CTO in a non-IRA. A total of 21 patients (6.2%) underwent additional revascularization within 1 year after the index event. Of these 21 patients, 7 had undergone coronary artery bypass grafting and 14 repeat PCI. No differences were found in the proportions of patients undergoing additional revascularization within 1 year after the index event among the 3 groups.
| Characteristics | SVD (n = 131; 45%) | MVD Without CTO (n = 92; 32%) | MVD With CTO (n = 69; 24%) | p Value |
|---|---|---|---|---|
| Baseline | ||||
| Age ≥75 years | 17 (13%) | 25 (27%) | 17 (25%) | 0.02 |
| Men | 83 (63%) | 63 (69%) | 51 (74%) | 0.13 |
| Hypertension | 27 (21%) | 22 (24%) | 21 (30%) | 0.13 |
| Smoker | 54 (41%) | 25 (27%) | 23 (33%) | 0.15 |
| Diabetes mellitus | 9 (6.9%) | 19 (21%) | 17 (25%) | <0.01 |
| Known hypercholesterolemia at admission | 14 (11%) | 19 (21%) | 20 (29%) | <0.01 |
| Family history of cardiovascular disease | 39 (30%) | 21 (23%) | 19 (28%) | 0.60 |
| Previous myocardial infarction | 28 (21%) | 31 (34%) | 39 (57%) | <0.01 |
| Previous revascularization | ||||
| Previous percutaneous coronary intervention | 6 (4.6%) | 7 (7.6%) | 10 (14%) | 0.05 |
| Previous coronary artery bypass grafting | 0 (0%) | 3 (3.3%) | 11 (16%) | <0.01 |
| Left ventricular ejection fraction <40% ⁎ | 70 (71%) | 56 (76%) | 55 (93%) | <0.01 |
| Angiographic | ||||
| Left anterior descending coronary artery related myocardial infarction | 69 (53%) | 39 (42%) | 36 (52%) | 0.72 |
| Pre-percutaneous coronary intervention Thrombolysis In Myocardial Infarction flow grade | 0.20 | |||
| 0 | 94 (72%) | 64 (70%) | 54 (78%) | |
| 1 | 15 (12%) | 4 (4.3%) | 3 (4.3%) | |
| 2 | 10 (7.6%) | 13 (14%) | 5 (7.2%) | |
| 3 | 12 (9.2%) | 11 (12%) | 7 (10%) | |
| Post-percutaneous coronary intervention Thrombolysis In Myocardial Infarction flow grade | 0.72 | |||
| 0 | 12 (9.2%) | 9 (9.8%) | 10 (15%) | |
| 1 | 4 (3.1%) | 5 (5.4%) | 1 (1.4%) | |
| 2 | 23 (18%) | 13 (14%) | 11 (16%) | |
| 3 | 92 (70%) | 65 (71%) | 47 (68%) | |
| Treatment | ||||
| Aspirin | 92 (70%) | 71 (77%) | 47 (68%) | 0.95 |
| Heparin | 112 (86%) | 84 (99%) | 60 (87%) | 0.43 |
| Glycoprotein IIb/IIIa blocker | 36 (27%) | 25 (27%) | 22 (32%) | 0.86 |
| β Blocker | 19 (15%) | 19 (21%) | 23 (33%) | 0.02 |
| Angiotensin-converting enzyme inhibitor | 25 (19%) | 15 (16%) | 6 (8.7%) | 0.11 |
| Lipid-lowering drug | 46 (39%) | 26 (32%) | 7 (12%) | <0.01 |
| Thrombosuction performed | 27 (21%) | 11 (12%) | 6 (8.7%) | 0.02 |
| Intra-aortic balloon pump | 70 (54%) | 56 (61%) | 47 (68%) | 0.04 |
| Stent placement | 87 (66%) | 60 (71%) | 42 (61%) | 0.28 |
| Multivessel primary percutaneous coronary intervention | 0 (0%) | 21 (23%) | 16 (23%) | <0.01 |
⁎ Left ventricular ejection fraction data were available for 232 of 292 patients.
Figure 1 shows the cumulative mortality for patients with single-vessel disease, MVD without CTO, and MVD with CTO in a non-IRA. At 1 year, the mortality rate in the total cohort was 44% (128 patients). Mortality increased significantly with the extent of coronary disease, as illustrated by the log-rank p values of mortality in patients with MVD without CTO versus that for patients with single-vessel disease (p = 0.03) and that for patients with CTO in a non-IRA versus patients with MVD without CTO (p = 0.02). The mortality rate at 1 year was 31% (41 patients) in the single-vessel disease group, 47% (43 patients) in the MVD without CTO group, and 64% (44 patients) in the MVD with CTO in a non-IRA group. The 1-year mortality rate in patients with MVD with and without CTO who underwent culprit lesion-only primary PCI or multivessel PCI was comparable (53% vs 60%, respectively, p = 0.50).
