Among patients with chronic stable angina, those with severe angina, large or multiple perfusion defects on functional testing, or a low threshold for induction of ischemia (Table 6-2) have a poor prognosis, with an annual mortality risk greater than 3%. If these high-risk features are associated with double- or triple-vessel disease, patients benefit from revascular-ization regardless of left ventricular function. In an analysis of 5303 patients of the CASS registry, surgical benefit was greatest in patients who exhibited at least 1 mm of ST-segment depression and who could exercise only into stage 1 or less. In the surgical group with triple-vessel disease and severe exercise-induced ischemia, 7-year survival was 81%, whereas it was
Table 6-2. Conditions Indicating Poor Prognosis* in Stable Angina
High-risk treadmill score
Stress-induced large or moderate size nuclear perfusion defect
(particularly if anterior wall) Stress-induced multiple perfusion defects with left ventricular dilation or increased lung parenchymal uptake of thallium-201 isotope
Echocardiographic wall motion abnormality involving >2 segments developing at a low dose of dobutamine (<10 |i.g/kg/min) or at a low heart rate (120 beats/min) Stress-induced echocardiographic evidence of extensive ischemia
*Average annual mortality risk >3%.
% Total myocardium ischemic
Figure 6-3. Observed cardiac death rates during a mean follow-up of 1.9 years in patients undergoing revascularization (Revasc) versus medical therapy (Medical Rx) as a function of the amount of inducible ischemia. *, P < .001. (From Hachamovitch R, Hayes SW, Friedman JD, et al: Comparison of the short-term survival benefit associated with revascularization compared with medical therapy in patients with no prior coronary artery disease undergoing stress myocardial perfusion single photon emission computed tomography. Circulation 2003;107:2900-2907.)
58% in the corresponding medical group.20 Likewise, in another registry including 2023 patients with severe angina and two-vessel disease, 6-year survival was 76% in patients treated medically and 89% in patients treated surgically (P < .001).21 Cox multi-variate analyses showed that surgical treatment was a beneficial independent predictor of survival for patients with two-vessel coronary disease and Canadian Heart Association class III or IV angina.
The ACIP study was a more recent trial that was designed to compare the efficacy of medical therapy versus revascularization.22 In ACIP, 558 patients with angiographically documented coronary artery disease, mostly multivessel disease, and stable coronary artery disease were randomly assigned to medical therapy, either adjusted to suppress angina or adjusted to suppress both angina and evidence of ischemia during ambulatory electrocardiographic (ECG) monitoring or revascularization with either PCI or CABG. Revas-cularization was significantly more effective in relieving ischemia than either of the medical strategies. During 1-year follow-up, the ACIP trial appeared to show better outcome in patients treated with revas-cularization. Mortality was 4.4% and 1.6% in the two conservative groups, whereas none of the patients in the revascularization group died during in the first year. The apparent benefit of revascularization therapy was largely confined to patients with double-or triple-vessel disease.
A recent registry of 10,627 consecutive patients who underwent exercise or adenosine myocardial perfusion single-photon emission computed tomography demonstrated that patients with a large ischemic area on functional testing benefit from revascularization. The patients included in this retrospective analysis had no prior MI or revascularization and were followed up for a mean of 1.9 years. The treatment, received within 60 days after stress testing, was revascularization by either CABG or PCI in 671 patients and medical therapy in 9956 patients. To adjust for nonrandomization of treatment, a propensity score was developed. On the basis of the Cox proportional hazards model predicting cardiac death, patients undergoing medical therapy demonstrated a survival advantage compared with patients undergoing revascularization in the setting of no or mild ischemia, whereas patients undergoing revasculariza-tion had an increasing survival benefit over patients undergoing medical therapy if moderate to severe ischemia was present (Fig. 6-3).23
Therefore, although adequately powered randomized trials addressing the impact of severe angina or large perfusion defects on outcome in patients with chronic stable angina are lacking, the bulk of the currently available evidence suggests that these patients benefit from revascularization, particularly if more than one vessel is affected.
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