Original article
Predicting therapeutic benefit from myocardial revascularization procedures: Are measurements of both resting left ventricular ejection fraction and stress-induced myocardial ischemia necessary?

This work was presented in part at the 75th Annual Scientific Sessions of the American Heart Association, Chicago, Ill, November 19, 2002, and was supported in part by grants from Bristol-Myers Squibb Medical Imaging and Astellas Inc.
https://doi.org/10.1016/j.nuclcard.2006.08.017Get rights and content

Background

We hypothesized that ejection fraction (EF) best predicts cardiovascular death but only measures of ischemia predict relative survival benefit from revascularization compared with medical therapy.

Methods and Results

We followed up 5366 consecutive patients without prior revascularization who underwent stress electrocardiography-gated myocardial perfusion single photon emission computed tomography (MPS) for 2.8 ± 1.2 years, during which 146 cardiac deaths occurred (2.7%, 1.0%/y). The treatment received within 60 days after MPS was used to define the subgroups (revascularization in 402 patients, with cardiac death occurring in 6.2%, vs medical therapy in 4964 patients, with cardiac death occurring in 2.4%; P < .0001, χ2 = 18.7). Adjustment for nonrandomized treatment assignment used a propensity score based on logistic regression modeling of referral to revascularization. The percent of myocardium that was ischemic was the most important predictor of revascularization. The overall model (multivariate χ2 = 728, c index = 0.89, P < 10−5) was used as a propensity score. Cox proportional hazards analysis, assessing the relationship between MPS results, non-MPS covariates, and cardiac death, revealed that EF was superior to percent ischemic myocardium in the prediction of cardiac death after adjustment for pre-MPS data and the propensity score. However, an interaction between percent ischemic myocardium and revascularization was present such that, irrespective of EF, patients with little or no ischemia had an improved survival rate with medical therapy, whereas with increasing ischemia, progressive improvements in survival rate were noted with revascularization.

Conclusions

Although EF predicts cardiac death, only inducible ischemia identifies which patients have a short-term benefit from revascularization.

Section snippets

Study Population

We identified 8253 consecutive unique patients who underwent exercise or adenosine gated MPS between June 1994 and February 1999 at Cedars-Sinai Medical Center (Los Angeles, Calif). Of these, 5644 (68%) had no prior coronary revascularization, known valvular disease, or nonischemic cardiomyopathy. Successful follow-up was completed in 95.1% of these patients, leaving a final study population of 5366 patients who were followed up for a mean of 2.8 ± 1.2 years. Patients were separated into 2

Patient Characteristics

Comparison of baseline characteristics of the 4964 patients treated medically and the 402 patients treated with early revascularization revealed multiple differences (Table 1), with the latter being “sicker.” They were older, were more likely to have had prior MI, and more frequently had hypertension, diabetes, anginal symptoms, dyspnea, and an abnormal rest electrocardiogram. Patients without prior MI had a significantly lower likelihood of CAD or ischemia than those with prior MI (median

Discussion

Our central goal was to determine whether the gated MPS measures of stress perfusion and poststress LV EF predicted which patients would accrue a survival benefit with revascularization versus medical therapy after stress MPS in an observational series of patients treated either medically or with revascularization after stress MPS. The unadjusted risk of cardiovascular death increased exponentially as a function of both decreasing EF and increasing percent ischemic myocardium. After adjustment

Acknowledgment

Various nuclear medicine hardware and software manufactures have an agreement with Cedars-Sinai Medical Center, through which the Medical Center receives royalties based on the distribution of the quantitative gated SPECT software. A portion of these royalties is shared by Drs Berman and Germano.

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