Safety and efficacy of colonoscopy after myocardial infarction: an analysis of 100 study patients and 100 control patients at two tertiary cardiac referral hospitals.

Background: The purpose of this study is to analyze the risks vs. the benefits of colonoscopy soon after myocardial infarction.
Methods: A total of 100 consecutive patients undergoing colonoscopy within 30 days after myocardial infarction at two large tertiary cardiac referral hospitals were studied. The study group was compared with 100 control patients with neither myocardial infarction nor unstable angina during the preceding 6 months (matched for age, colonoscopy indication, and colonoscopist) who underwent colonoscopy.
Results: Indications for colonoscopy were bleeding per rectum (37 patients), fecal occult blood (36 patients, hematocrit < 30% in 25), iron deficiency anemia (11 patients, hematocrit < 25% in 9), and other (16 patients). Colonoscopy was performed at a mean of 15.5 (8.3) days after myocardial infarction. Two patients underwent colonoscopic colonic decompression. Colonoscopy was diagnostic in 46 (47%) of the study patients vs. 41% of the control patients ( p = 0.47, chi-square test). The relative rate of ischemic colitis was significantly higher in study vs. control patients (14 vs. 2, p < 0.005). Other diagnoses in study patients were the following: colon cancer (8), bleeding internal hemorrhoids (5), pseudomembranous colitis (5), high-risk adenomatous polyp (large or villous histopathology) (4), and other (10). Urgent colonoscopy was diagnostic in 63% of cases. Twenty-three patients had a major therapeutic benefit consequent to colonoscopy, including colon cancer surgery in 5. Study patients were significantly sicker than control patients (APACHE II score 9.9 [4.3] vs. 7.4 [2.8], p < 0.0001) and suffered significantly more colonoscopic complications compared with control patients (9 vs. 1; OR 5.2: 95% CI [1.2, 9.8], p < 0.03). Minor complications without clinical sequelae occurred in 8 study patients (asymptomatic hypotension or bradycardia). One major complication occurred in this group that was probably not procedure related.
Conclusions: Colonoscopy in patients with a recent myocardial infarction is associated with a higher rate of minor, transient, and primarily cardiovascular complications compared with control patients but is relatively infrequently associated with major complications. Colonoscopy is beneficial and indicated after myocardial infarction, despite a higher risk, in certain circumstances. The relative frequency of ischemic colitis was relatively high in study patients.