Is It Really Safe to Perform Bronchoscopy After a Recent Acute Myocardial Infarct?

Abstract

Another icon of medical practice is challenged in the article by Dweik and colleagues in this issue of CHEST (see page 825). In a retrospective study, they found that bronchoscopy is not contraindicated in patients who have suffered recent acute myocardial infarction (AMI). The general nature of the challenge is not new, as other studies have demonstrated that various types of surgery can be done safely after recent AMI. In fact, those with recent AMI can and do survive coronary artery bypass graft surgery (CABG), in spite of the prevalent notion that surgical procedures performed in the 3 to 6 months following AMI predispose the patient to a bad outcome. If that is the case, what can we learn to support or refute the notion that any surgical procedure that is not truly emergent, including bronchoscopy, should not be done in patients with recent AMI? Recent studies will provide some answers.Most studies of perioperative mortality when surgery is performed after recent AMI are retrospective, as was the current study about the risks of bronchoscopy during this time frame. Dweik and colleagues did intend to the indications for bronchoscopy procedure was truly appropriate for the patient. All they really intended with their study was to determine whether recent AMI patients who underwent bronchoscopy survived the procedure and/or had other nonfatal complications that could be attributed to the performance of bronchoscopy. The number of patients in their study was not large, and the inhospital mortality was 25%. Only one of the deaths (5% of the total who underwent bronchoscopy) occurred within hours of having bronchoscopy performed; this patient had active ischemia before, during, and after the bronchoscopy. It is possible that bronchoscopy contributed to the patient's death, but this could not be stated with certainty.A study from the Massachusetts General Hospital1Goldman L Caldera DL Nussbaum SR et al.Multifactorial index of cardiac risk in noncardiac surgical procedures.N Engl J Med. 1977; 297: 845-850Crossref PubMed Scopus (2057) Google Scholar of 1,001 patients who underwent major noncardiac operations concluded that there were 9 important preoperative variables that could be used to predict the likelihood of life-threatening or fatal cardiac complications. One such predictor in this study was MI within the preceding 6 months. Another variable was the presence of a third heart sound or jugular venous distention. The latter two findings indicate cardiac dysfunction. Congestive heart failure (CHF) and impaired left ventricular function (assessed by echocardiogram) have been confirmed by many subsequent studies as significant predictors of perioperative mortality, when major surgical procedures were required. For noncardiac operations, this was best demonstrated among recent AMI patients who required appendectomy for acute appendicitis and hip surgery for fractures. Using an intention-to-treat principle, which reduces the bias in evaluating operative risk, Dirksen and Kjoller2Dirksen A Kjoller E Cardiac predictors of death after non-cardiac surgery evaluated by intention to treat.BMJ. 1988; 297: 1011-1013Crossref PubMed Scopus (15) Google Scholar, 3Kjoller E Dirksen A Assessment of the surgical risk: Is the time between myocardial infarction and a possible surgical procedure of significance for a surgical risk?.Ugeskr Laeger. 1991; 153: 1854-1857PubMed Google Scholar provided convincing data that mortality in these two types of surgery is related to CHF and not to the time between AMI and surgery. Other studies in patients undergoing CABG4Fremes SE Goldman BS Christakis GT et al.Current risk of coronary bypass for unstable angina.Eur J Cardiothorac Surg. 1991; 5: 235-243Crossref PubMed Scopus (27) Google Scholar, 5Kennedy JW Ivey TD Misbach G et al.Coronary artery bypass graft surgery early after acute myocardial infarction.Circulation. 1989; 79: 173-178Google Scholar, 6Kouchoukos TN Murphy S Philpott T et al.Coronary artery bypass grafting for postinfarction angina pectoris.Circulation. 1989; 79: 168-172Google Scholar, 7Hochberg MS Parsonnet V Gielchinsky I et al.Timing of coronary revascularization after acute myocardial infarction.Ann Thorac Surg. 1981; 88: 914-921Google Scholar have led to the same conclusions: that depressed left ventricular function and CHF were the most important predictors of perioperative mortality, rather than the interval between the AMI and the surgery.The study by Dweik and colleagues should not be interpreted as a free license to begin performing bronchoscopy shortly after AMI. The indications to perform bronchoscopy should still be rigorously applied. This is especially true if the patient has CHF. When there is concern about left ventricular dysfunction, an echocardiogram before proceeding with bronchoscopy may help in cases where the indications are less emergent. Good sedation to allay anxiety, careful attention to the details of monitoring hemodynamic parameters, and assuring adequate oxygenation during the procedure, should improve the safety margin in those patients with recent AMI who truly must be subjected to bronchoscopy. Another icon of medical practice is challenged in the article by Dweik and colleagues in this issue of CHEST (see page 825). In a retrospective study, they found that bronchoscopy is not contraindicated in patients who have suffered recent acute myocardial infarction (AMI). The general nature of the challenge is not new, as other studies have demonstrated that various types of surgery can be done safely after recent AMI. In fact, those with recent AMI can and do survive coronary artery bypass graft surgery (CABG), in spite of the prevalent notion that surgical procedures performed in the 3 to 6 months following AMI predispose the patient to a bad outcome. If that is the case, what can we learn to support or refute the notion that any surgical procedure that is not truly emergent, including bronchoscopy, should not be done in patients with recent AMI? Recent studies will provide some answers. Most studies of perioperative mortality when surgery is performed after recent AMI are retrospective, as was the current study about the risks of bronchoscopy during this time frame. Dweik and colleagues did intend to the indications for bronchoscopy procedure was truly appropriate for the patient. All they really intended with their study was to determine whether recent AMI patients who underwent bronchoscopy survived the procedure and/or had other nonfatal complications that could be attributed to the performance of bronchoscopy. The number of patients in their study was not large, and the inhospital mortality was 25%. Only one of the deaths (5% of the total who underwent bronchoscopy) occurred within hours of having bronchoscopy performed; this patient had active ischemia before, during, and after the bronchoscopy. It is possible that bronchoscopy contributed to the patient's death, but this could not be stated with certainty. A study from the Massachusetts General Hospital1Goldman L Caldera DL Nussbaum SR et al.Multifactorial index of cardiac risk in noncardiac surgical procedures.N Engl J Med. 1977; 297: 845-850Crossref PubMed Scopus (2057) Google Scholar of 1,001 patients who underwent major noncardiac operations concluded that there were 9 important preoperative variables that could be used to predict the likelihood of life-threatening or fatal cardiac complications. One such predictor in this study was MI within the preceding 6 months. Another variable was the presence of a third heart sound or jugular venous distention. The latter two findings indicate cardiac dysfunction. Congestive heart failure (CHF) and impaired left ventricular function (assessed by echocardiogram) have been confirmed by many subsequent studies as significant predictors of perioperative mortality, when major surgical procedures were required. For noncardiac operations, this was best demonstrated among recent AMI patients who required appendectomy for acute appendicitis and hip surgery for fractures. Using an intention-to-treat principle, which reduces the bias in evaluating operative risk, Dirksen and Kjoller2Dirksen A Kjoller E Cardiac predictors of death after non-cardiac surgery evaluated by intention to treat.BMJ. 1988; 297: 1011-1013Crossref PubMed Scopus (15) Google Scholar, 3Kjoller E Dirksen A Assessment of the surgical risk: Is the time between myocardial infarction and a possible surgical procedure of significance for a surgical risk?.Ugeskr Laeger. 1991; 153: 1854-1857PubMed Google Scholar provided convincing data that mortality in these two types of surgery is related to CHF and not to the time between AMI and surgery. Other studies in patients undergoing CABG4Fremes SE Goldman BS Christakis GT et al.Current risk of coronary bypass for unstable angina.Eur J Cardiothorac Surg. 1991; 5: 235-243Crossref PubMed Scopus (27) Google Scholar, 5Kennedy JW Ivey TD Misbach G et al.Coronary artery bypass graft surgery early after acute myocardial infarction.Circulation. 1989; 79: 173-178Google Scholar, 6Kouchoukos TN Murphy S Philpott T et al.Coronary artery bypass grafting for postinfarction angina pectoris.Circulation. 1989; 79: 168-172Google Scholar, 7Hochberg MS Parsonnet V Gielchinsky I et al.Timing of coronary revascularization after acute myocardial infarction.Ann Thorac Surg. 1981; 88: 914-921Google Scholar have led to the same conclusions: that depressed left ventricular function and CHF were the most important predictors of perioperative mortality, rather than the interval between the AMI and the surgery. The study by Dweik and colleagues should not be interpreted as a free license to begin performing bronchoscopy shortly after AMI. The indications to perform bronchoscopy should still be rigorously applied. This is especially true if the patient has CHF. When there is concern about left ventricular dysfunction, an echocardiogram before proceeding with bronchoscopy may help in cases where the indications are less emergent. Good sedation to allay anxiety, careful attention to the details of monitoring hemodynamic parameters, and assuring adequate oxygenation during the procedure, should improve the safety margin in those patients with recent AMI who truly must be subjected to bronchoscopy.