Several reports have alluded to the adverse effect of chronic obstructive pulmonary disease (COPD) on long-term prognosis of patients with myocardial infarction (MI). Little information is available, however, regarding the effects of a decrease in cardiopulmonary reserve imposed by COPD on in-hospital outcome of acute MI. This study aimed to evaluate the impact of COPD on acute-phase outcome of patients with acute MI. From a cohort of 3,249 consecutive patients with ST-elevation MI who underwent primary or rescue percutaneous coronary intervention, 365 patients were identified as having coexistent COPD. Their clinical presentation and in-hospital outcome were compared to those of 2,884 patients without COPD. The primary end point was a composite of in-hospital death or cardiogenic shock on presentation. Patients with COPD were older (p <0.001), more often women (p <0.001), and smokers (p <0.001). They had higher prevalence of chronic renal insufficiency (p <0.001), systemic hypertension (p = 0.001), and diabetes mellitus (p = 0.01). Patients with COPD had higher rates of the composite end point of death or cardiogenic shock (p <0.0001). After multivariate analysis, COPD remained a strong independent predictor of the composite end point of death or cardiogenic shock (p = 0.008). In conclusion, COPD is a very strong predictor of hemodynamic compromise resulting in death or cardiogenic shock in patients presenting with ST-elevation MI. This observation suggests that hemodynamic and pulmonary consequences of COPD decrease the capacity of the circulatory system to adjust to the effects of acute MI. Recognition of the potential for combined therapy is vital.
Pre-existing chronic obstructive pulmonary disease (COPD) is common in patients with acute myocardial infarction (MI). It is plausible that in such instances pulmonary vascular disease, pulmonary hypertension, hypoxemia, and acidosis associated with COPD decrease cardiac reserve and affect cardiac performance. Thus, in patients with acute MI, a major hemodynamic challenge, the decrease in cardiac reserve imposed by COPD may lead to greater hemodynamic compromise and a greater risk of other cardiovascular complications. Several reports have alluded to the adverse effect of COPD on the long-term prognosis of patients with heart disease, but little information is available regarding the acute effects of the decrease in cardiopulmonary reserve imposed by COPD on the outcome of acute MI, a time when it is likely to have the greatest impact on outcome. This study was designed to address whether COPD strongly affects acute-phase outcomes of MI.
Methods
A prospective registry of patients undergoing percutaneous coronary intervention at our institution is maintained. From this registry, 3,249 consecutive patients with ST-elevation MI (STEMI) who underwent primary or rescue percutaneous coronary intervention from April 1999 to June 2008 were selected for study. All gave written informed consent for the percutaneous coronary intervention procedure. This analysis was conducted with the approval of the institutional review board. In this registry, COPD was defined as the reported need for pharmacologic therapy for COPD and/or a 1-second forced expiratory volume <70% of the predicted value. Accordingly, 365 of the 3,249 patients (11.1%) were considered to have COPD before the acute MI.
The primary outcome was a composite of cardiogenic shock on presentation or all-cause in-hospital mortality. We reasoned that an inability to overcome the decreased cardiac reserve imposed by the acute MI would likely result in the former and less often in the latter. Cardiogenic shock was defined as hypotension (systolic blood pressure <90 mm Hg for ≥30 minutes) or the need for supportive measures to maintain a systolic blood pressure ≥90 mm Hg, end-organ hypoperfusion (cool extremities or urine output <30 ml/hour), and a heart rate ≥60 beats/min. Hemodynamic criteria were a cardiac index of ≤2.2 L/min per square meter of body surface area and a pulmonary-capillary wedge pressure ≥15 mm Hg. Patients with identifiable and successfully treated extra myocardial factors (e.g., hypovolemia, arrhythmia, pain, vasovagal reaction, hypoxemia, and acidosis) were not included as having cardiogenic shock.
Several secondary outcomes, including each of the 2 components of the primary outcome, were also considered. These included cardiac death, defined as all deaths in which a noncardiac cause could not be demonstrated or a neurologic event including stroke or a transient ischemic attack. Periprocedural nephropathy was defined as an absolute increase in serum creatinine >0.5 mg/dl after percutaneous coronary intervention. Arrhythmia was entered as present when atrioventricular block, ventricular tachycardia, ventricular fibrillation, atrial fibrillation, atrial flutter, supraventricular tachycardia and sinus bradycardia were detected. Major bleeding was defined as a decrease ≥15% in hematocrit and/or occurrence of gastrointestinal bleeding and/or intracerebral bleeding. Need for transfusion was defined as the need for whole blood or packed red blood cells due to a hemorrhagic event. Procedural success was defined as attainment of Thrombolysis In Myocardial Infarction grade 3 flow and residual stenosis <30%.
An experienced, trained data center staff, unaware of the purpose and design of this project, obtained clinical information by hospital chart review. The staff entered demographic, clinical, and procedural data and in-hospital outcomes into an ongoing database. All data management and analyses were performed by a dedicated data coordinating center (Data Center, Cardiovascular Research Institute, Washington, DC).
Continuous variables are presented as mean ± SD and compared using Student’s t test. Categorical variables are presented as frequencies and percentages and were compared using chi-square test or Fisher’s exact probability test. Univariable and multivariable logistic regression analyses were performed to identify independent predictors of the composite end point of all-cause death or cardiogenic shock. Variables with a p value <0.1 on univariable analysis were entered into a multivariable Cox model to adjust for baseline differences. All variables were entered into the model in their original form without transformation. Statistical analysis was performed using SAS 9.1 (SAS Institute, Cary, North Carolina). Statistical significance was considered at a p value <0.05.
Results
Baseline clinical characteristics are listed in Table 1 . Patients with COPD were older (p <0.001) and more often women (p <0.001). Further, they more often had chronic renal insufficiency (p <0.001), systemic hypertension (p = 0.001), diabetes mellitus (p = 0.01), and had ever been smokers (p <0.001). They more often reported previous coronary artery bypass graft surgery (p = 0.002) and percutaneous coronary intervention (p <0.001). Table 2 lists baseline angiographic and procedural characteristics of the 2 groups based on by-lesion analysis. Lesions located in a saphenous vein graft were more frequently targeted (p <0.001) and those in the left anterior descending coronary artery (p = 0.04) were treated less often in the COPD group. Drug-eluting stents were deployed less frequently in patients with COPD (p = 0.008). Angiographic success was very high in the 2 groups.
| Cardiovascular Risk Factors | COPD | p Value | |
|---|---|---|---|
| Yes (n = 365) | No (n = 2,884) | ||
| Age (years) | 66.2 ± 13.6 | 60.7 ± 13.8 | <0.001 |
| Men | 215 (59.1%) | 1,971 (68.5%) | <0.001 |
| Systemic hypertension ⁎ | 313 (86.9%) | 2,294 (79.7%) | 0.001 |
| Hypercholesterolemia † | 302 (84.8%) | 2,371 (83.1%) | 0.4 |
| Diabetes mellitus | 128 (35.8%) | 833 (29.1%) | 0.01 |
| Current smoker | 146 (40.1%) | 1,065 (36.9%) | 0.2 |
| Ever smoked | 258 (70.9%) | 55.7 (53.1%) | <0.001 |
| Body mass index (kg/m 2 ) | 28.8 ± 7.5 | 29.3 ± 6.1 | 0.2 |
| Chronic renal insufficiency ‡ | 85 (23.7%) | 337 (11.8%) | <0.001 |
| Previous coronary artery bypass grafting | 59 (16.4%) | 314 (11.0%) | 0.002 |
| Previous percutaneous coronary intervention | 89 (26.7%) | 455 (16.8%) | <0.001 |
| Number of narrowed coronary arteries | 2.0 ± 0.87 | 2.0 ± 0.85 | 0.6 |
| Maximum creatine phosphokinase-MB (ng/ml) | 59.0 ± 93.2 | 63.5 ± 97.2 | 0.4 |
⁎ History of hypertension diagnosed and/or treated with medication or currently being treated with diet and/or medication by a physician.
† Includes patients with previously documented diagnosis of hypercholesterolemia. The patient may be treated with diet or medication. A new diagnosis could be made during this hospitalization with an increased total cholesterol level >160 mg/dl. Does not include increased triglycerides.
‡ Previously diagnosed or treated with medication, diet, or dialysis by a physician. Diagnosis at admission if a baseline creatinine level >2.0 mg/dl was found.
| Lesion Based | COPD | p Value | |
|---|---|---|---|
| Yes (n = 606) | No (n = 4,552) | ||
| Coronary narrowing location | |||
| Left main coronary artery | 7 (1.2%) | 35 (0.8%) | 0.3 |
| Left anterior descending coronary artery | 204 (33.8%) | 1,723 (37.9%) | 0.04 |
| Left circumflex coronary artery | 138 (22.8%) | 969 (21.3%) | 0.4 |
| Right coronary artery | 221 (34.9%) | 1,634 (36.0%) | 0.6 |
| Saphenous vein graft | 42 (7.0%) | 178 (3.9%) | <0.001 |
| Restenosis | 22 (3.6%) | 129 (2.8%) | 0.3 |
| American College of Cardiology/American Heart Association type C lesion | 211 (35.9%) | 1,495 (34.0%) | 0.4 |
| Number of lesions dilated | 1.6 ± 0.82 | 1.5 ± 1.09 | 0.3 |
| Number of implanted stents | 1.2 ± 0.89 | 1.3 ± 0.91 | 0.6 |
| Drug-eluting stent | 217 (45.4%) | 1,988 (51.8%) | 0.008 |
| Angiographic success | 579 (95.9%) | 4,370 (96.8%) | 0.2 |
The primary end point of cardiogenic shock on admission or death occurred significantly more often in patients with COPD (23.1% vs 14.4%, p <0.0001). Individual components were also significantly more frequent in patients with COPD. In-hospital mortality was greater (6.3% vs 3.4%, p = 0.006) as was cardiogenic shock (18.4% vs 10.4%, p <0.001; Figure 1 , Table 3 ). Secondary indicators reinforce the conclusion that presence of COPD has a detrimental effect on hemodynamic severity of acute MI. Length of stay (p <0.001) and intensive care unit stays (p = 0.004) were longer, postprocedural nephropathy (p = 0.01) was more frequent, and emergency use of an intra-aortic balloon pump (p = 0.004) was more common in patients with COPD. Hemorrhagic complications were more frequent in patients with COPD. Major bleeding (p = 0.01) and of transfusion (p = 0.002) were significantly greater.
| Variable | COPD | p Value | |
|---|---|---|---|
| Yes (n = 365) | No (n = 2,884) | ||
| Primary end point | |||
| Death or cardiogenic shock | 84 (23.1%) | 415 (14.4%) | <0.0001 |
| Secondary end point | |||
| Cardiogenic shock | 66 (18.4%) | 296 (10.4%) | <0.001 |
| Death | 23 (6.3%) | 98 (3.4%) | 0.006 |
| Cardiac death | 18 (4.9%) | 71 (2.5%) | 0.006 |
| Emergency intra-aortic balloon pump | 56 (15.4%) | 298 (10.4%) | 0.004 |
| Arrhythmia | 57 (17.0%) | 367 (13.6%) | 0.1 |
| Urgent coronary artery bypass graft | 7 (1.9%) | 46 (1.6%) | 0.7 |
| Recurrent Q-wave myocardial infarction | 2 (0.6%) | 20 (0.7%) | 0.99 |
| Stent thrombosis | 1 (0.3%) | 3 (0.1%) | 0.4 |
| Periprocedural nephropathy | 37 (11.5%) | 189 (7.4%) | 0.01 |
| Any neurologic event | 4 (1.1%) | 26 (0.9%) | 0.8 |
| Major bleeding | 32 (8.8%) | 157 (5.4%) | 0.01 |
| Transfusion | 55 (15.5%) | 282 (10.1%) | 0.002 |
| Length of stay (days) | 6.5 ± 6.2 | 4.64 ± 5.11 | <0.001 |
| Intensive care unit (days) | 3.2 ± 3.9 | 2.27 ± 3.00 | 0.004 |
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