Author + information
- Asim A. Mohammed, MBBS†,
- Andrew Yang†,
- Kimberly Shao†,
- Angela DiSabatino†,
- Ray Blackwell, MD†,
- Michael Banbury, MD†,
- William S. Weintraub, MD† and
- Andrew Doorey, MD†,⁎ ()
- ↵⁎Christiana Care Health System, Cardiology Section, Suite 2E99, Christiana Care Health System, 4755 Ogletown-Stanton Road, Newark, Delaware 19718
To the Editor:
Left main coronary artery (LMCA) vasospasm induced by angiographic catheters during coronary angiography, although uncommon, is a recognized complication of this procedure (1,2). However, the inability to distinguish vasospasm from obstructive disease of the LMCA can lead to inappropriate referral for coronary artery bypass graft (CABG) surgery (2). The incidence of patients with LMCA vasospasm who undergo unnecessary CABG is unknown. Accordingly, we sought to identify patients with LMCA vasospasm who were falsely diagnosed with LMCA atherothrombotic disease and then underwent CABG.
All patients who underwent CABG with angiographically significant LMCA atherothrombotic disease (stenosis of ≥ 50%) between January 2000 and July 2011 at Christiana Care Health System were identified using the Society of Thoracic Surgeons database. Among these patients, the patients who had coronary angiography before and after CABG at our medical center were identified using the American College of Cardiology National Cardiovascular Registry CathPCI database. Data including age, sex, reason for cardiac catheterization, and findings were obtained by chart review. We relied on the official catheterization report for stenosis severity, because not all films were still available for review. Patients with repeat cardiac catheterization after CABG that showed LMCA stenosis ≤ 25% were identified as cases of probable LMCA vasospasm. In addition, cases with occlusion of left-sided bypass grafts were also identified.
A total of 2,313 patients underwent CABG with a significant LMCA stenosis. Of these, 385 patients had coronary angiography before and after CABG at our facility. Patients' mean age was 63 years, and 62.5% were men. The most common indication for initial cardiac catheterization was unstable angina (56%). The mean interval of coronary angiography following CABG was 4.8 years. Significant LMCA stenosis was absent in 16 of 385 (4.1%) patients on repeat cardiac catheterization after CABG. At post-CABG cardiac catheterization, 5 of 15 (33.3%) internal mammary conduits to the left anterior descending artery were occluded (Table 1). Spasm was inadvertently confirmed in 1 patient who had unstable angina, a moderately severe angiographic left main stenosis with catheter damping, and a critically narrowed (<4 mm2) lumen identified by intravascular ultrasound (IVUS). When subsequent angiography was believed to be normal, the previous IVUS images showed the LMCA to be critically narrow, but absent significant atherosclerosis in the media, which strongly suggested spasm.
Catheter-induced vasospasm during coronary angiography has been described (1,2), and if unrecognized or resistant to vasodilators, it can be misinterpreted as LMCA atherothrombotic disease and referred for CABG. Edris et al. (2) reported 2 patients with LMCA vasospasm who were referred for CABG, and repeat coronary angiography showed a normal LMCA after 6 years in the first patient and after just 2 days in the second patient. In a large study of 7,295 retrospectively reviewed coronary angiograms, Chang et al. (3) found 30 cases of catheter-induced LMCA vasospasm (incidence, 0.41%). In their study, factors predictive of LMCA spasm were increased catheter-to-LM diameter ratio, catheter-to-LM wall contact, vessel bulging, and acute catheter-to-LM angle.
Catheter-induced spasm must be considered in the diagnosis of LMCA disease. However, interventional cardiologists are appropriately concerned about prolonging catheterization and performing additional procedures for suspected significant LMCA lesions, given the high risks involved. Given these risks, some cardiologists' routinely place intra-aortic balloons pumps and begin intravenous heparin and nitroglycerin with suspected LMCA lesions. A leading text on invasive cardiology describes significant LMCA stenosis as a very high-risk situation and suggests a “hit and run” technique of brief engagements with minimal contrast injections to get enough information to proceed, yet not jeopardize patients' safety (4). Given these reasons, the assessment of LMCA stenosis remains challenging. Attempts to ameliorate possible spasm by using intracoronary nitroglycerin seems like a reasonable routine in hemodynamically stable patients with significant LM stenosis.
Another concern in referring these patients for CABG is occlusion of important bypass grafts from competitive flow from patent native LMCA, as shown in previous studies (5). In our study, 33.3% patients had occluded internal mammary conduits to the left anterior descending artery, likely from similar physiology.
There were several limitations to this study. This was a retrospective study based on chart review; we were dependent on the catheterization report for assessment of LMCA stenosis. There were other possibilities, besides spasm, as to how a lesion that might be present on first, angiogram might be absent on a subsequent angiogram; these include overcall of the pre-CABG angiogram, an undercall of the post-CABG angiogram, development of diffuse atherosclerosis when the original lesion was focal, possible alteration of flow patterns that might have been altered by the presence of grafts and differing vasomotor tone, and angulations between the 2 studies. In addition, only a minority of the patients who had CABG for LMCA disease had a repeat coronary angiography at our facility; thus, we might have either underestimated or overestimated the incidence of patients who underwent CABG for LMCA spasm during this time. Nonetheless, our findings, confirmed in 1 patient to be spasm with IVUS and strongly suggested in the others, when added to previous observations, suggest that LM spasm is a finite but underdiagnosed entity, at times resulting in inappropriate bypass surgery.
- American College of Cardiology Foundation
- Chang K.S.,
- Wang K.Y.,
- Yao Y.W.,
- et al.
- Morton K.,
- Pranav P.