The development of more sophisticated testing modalities now permits the identification of coronary artery narrowing in asymptomatic adults. The images obtained in these studies provide potential targets for intervention-based therapy. In our procedurally oriented medical reimbursement system, the detection of coronary stenosis often results in a therapeutic cascade that includes formal coronary angiography, angioplasty, and stenting and/or coronary artery bypass grafting (CABG)—even though such interventions may not prolong life or prevent future myocardial infarction (MI).1 Each year Americans undergo about 1,000,000 angioplasties and more than 350,000 CABG procedures.2
Procedures of doubtful necessity result in considerable needless costs. The expense of angioplasty plus appropriate adjunctive pharmacotherapy is significantly greater than that of aggressive medical management, especially now that generic versions of many antianginal drugs are available. Moreover, few practitioners are aware that the cost of intervention may include cognitive impairment.
COGNITIVE DECLINE CAN FOLLOW CABG
Several important studies have addressed the issue of cognitive decline after CABG. A study published in 1986 involved 298 patients undergoing CABG who were tested 2 days before surgery using a battery of 10 standard tests of intellectual function. A total of 235 patients (79% of the cohort) showed cognitive impairment 7 days after surgery.3
In a prospective study, 259 patients were assessed before CABG, 7 days after surgery, and 6 months after, again using a battery of 10 standard tests of intellectual function.4 Analysis of the test scores revealed that 147 patients (57%) showed a decline in at least 1 score at 6 months.
A study that involved early and long-term assessment of the cognitive decline that accompanies CABG enrolled 261 patients.5 The participants all underwent neurocognitive testing before their CABG procedure as a baseline; they were also evaluated before discharge, and at 6 weeks, 6 months, and 5 years after surgery. Among the patients studied, the incidence of cognitive decline was 53% at discharge, 36% at 6 weeks, 24% at 6 months, and 42% at 5 years. Cognitive decline at baseline was a significant predictor of long-term decline in functioning (P < .001). The results confirm the high prevalence of cognitive decline after CABG.5
The significant incidence of cognitive decline associated with conventional CABG has been attributed to the need to cannulate and cross-clamp the ascending aorta, during which maneuver microemboli may be released from the atherosclerotic vessel wall. However, a recent study of cognitive function after CABG debunked that theory. The Octopus study, a multicenter randomized controlled trial, compared the changes in cognitive function associated with pump-assisted bypass grafting with changes associated with off-pump CABG.6 The study enrolled 281 low-risk patients undergoing CABG between 1998 and 2000. The patients were randomly assigned to receive either a conventional pump-assisted procedure or an off-pump procedure. Five years after their surgery, surviving patients were assessed using validated neuropsychological tests administered by a trained psychologist. An equal number of patients (130) were alive in each group; cognitive outcomes were determined in 123 in the off-pump group and in 117 in the pump-assisted group. The study authors concluded that in low-risk patients undergoing CABG, whether a pump was used during the procedure had no effect on 5-year cognitive impairment or cardiac outcomes.
Four electronic databases were examined to identify the relevant literature on cognitive decline after CABG, from 1980 to the present.7 A total of 256 different studies were identified; 23 of these were selected, including 12 cohort studies and 11 intervention studies. A pooled analysis of 6 of these studies that were highly comparable revealed that 22.5% (95% confidence interval, 18.7 to 26.4) of the patients involved demonstrated a cognitive deficit 2 months after the procedure.
EFFECTS OF PTCA SIMILAR TO THOSE OF CABG
A comparison of the long-term cognitive effects of coronary angiography and CABG was undertaken as part of a study of economics and quality of life in patients enrolled in the Bypass Angioplasty Revascularization Investigation (BARI) study.8 A group of 125 patients with angina or demonstrated myocardial ischemia were randomly assigned to be treated with CABG or percutaneous transluminal coronary angioplasty (PTCA). Participants returned for reevaluation after 5 years. The study showed no significant differences in long-term cognitive function between patients treated with CABG and those treated with PTCA.
In the Stent or Surgery (SoS) trial,9 988 patients were randomly assigned to receive either PTCA supported by stent implantation or CABG. A sub-study evaluated neuropsychological outcomes after the interventions. A total of 145 patients (77 in the PTCA group and 68 in the CABG group) were compared. There was no significant difference between the treatment groups at 6 and 12 months on any of the measures used.
From these results, which show no difference in cognitive outcomes between CABG and PTCA, it is only logical to conclude that cognitive decline is as common in patients treated with PTCA as it is in those treated with CABG.
EFFICACY OF MEDICAL MANAGEMENT OF ANGINA
The recent Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation (COURAGE) study suggests that angina can be successfully managed with aggressive medical therapy, permitting a delay in the implementation of an invasive alternative. The study also suggests that this delay imposes no mortality cost.10-13
I believe that enough information is now available to suggest that invasive cardiovascular procedures carry a degree of cognitive risk, and that for most patients who have not sustained an acute MI and those with chronic stable angina, an appropriate trial of aggressive medical management of adequate duration should be the initial approach to therapy.
As awareness grows, both of the cognitive risks associated with invasive cardiovascular procedures and of the efficacy of medical management of cardiovascular disease, patients and their physicians will become increasingly amenable to initiating and adhering to an aggressive medical program that reduces the need for an invasive procedure. Surely avoiding possible cognitive impairment is a strong incentive for most patients.
1. Nash DT. The case for medical treatment in chronic stable coronary artery disease. Arch Intern Med. 2005;165:2587-2589.
2. American Heart Association. Heart disease and stroke statistics—2004 update. http://www.americanheart.org/downloadable/heart/ 1079736729696HDSStats2004UpdateREV3-19-04.pdf. Accessed October 16, 2007.
3. Shaw PJ, Bates D, Cartlidge NE, et al. Early intellectual dysfunction following coronary bypass surgery. Q J Med. 1986;58:59-68.
4. Toner I, Taylor KM, Newman S, Smith PL. Cerebral functional changes following cardiac surgery: neuropsychological and EEG assessment. Eur J Cardiothorac Surg. 1998;13:13-20.
5. Newman MF, Kirchner JL, Phillips-Bute B, et al. Longitudinal assessment of neurocognitive function after coronary-artery bypass surgery. N Engl J Med. 2001;344:395-402.
6. van Dijk D, Spoor M, Hijman R, et al; Octopus Study Group. Cognitive and cardiac outcomes 5 years after off-pump vs on-pump coronary artery bypass graft surgery. JAMA. 2007;297:701-708.
7. van Dijk D, Keizer AM, Diephuis JC, et al. Neurocognitive dysfunction after coronary artery bypass surgery: a systematic review. J Thorac Cardiovasc Surg. 2000;120:632-639.
8. Hlatky MA, Bacon C, Boothroyd D, et al. Cognitive function 5 years after randomization to coronary angioplasty or coronary artery bypass graft surgery. Circulation. 1997;96(suppl 9):II-11-4-II-15.
9. Wahrborg P, Booth JE, Clayton T, et al. Neuropsychological outcome after percutaneous intervention or coronary artery bypass grafting: results from the Stent or Surgery (SoS) Trial. Circulation. 2004;110:3411-3417.
10. Boden WE, O'Rourke RA, Teo KK, et al. Optimal medical therapy with or without PCI for stable coronary disease. N Engl J Med. 2007;356:1503-1516.
11. Chaitman BR, Pepine CJ, Parker JO;Combination Assessment of Ranolazine in Stable Angina (CARISA) Investigators. Effects of ranolazine with atenolol, amlodipine, or diltiazem on exercise tolerance and angina frequency in patients with severe chronic angina: a randomized controlled trial. JAMA. 2004;291:309-316.
12. Pfisterer M, Buser P, Osswald S. Outcome of elderly patients with chronic symptomatic coronary artery disease with an invasive vs optimized medical treatment strategy: one-year results of the randomized TIME trial. JAMA. 2003;289:1117-1123.
13. Nash DT. Invasive versus intensive medical therapy for stable angina. Patient Care. 2006;40:51-58.