Methods

The angiographic and myocardial perfusion scintigraphic databases of the University of Aachen were matched for the time period from January 1, 2000, to December 31, 2003, to define patients with nonacute significant CAD (diameter stenosis >50% on quantitative coronary angiography) who had positive stress single-photon emission computed tomographic (SPECT) results and were subsequently treated with medical therapy or PCI including stent placement. The angiographic database included 20,384 patients during this period, and the myocardial perfusion scintigraphic database included 4,903 patients. A total of 1,018 stable patients were identified to have positive stress myocardial perfusion scintigraphic findings and significant CAD on quantitative coronary angiography and were treated medically or by PCI. Two hundred sixty-six patients were treated using medical therapy.

These 266 patients were matched against 752 patients with positive SPECT findings and PCI as treatment. Patient characteristics and angiographic and SPECT findings were matched with the medical treatment group, considering the following parameters in sequential selection: gender, age (±1 year), number and location of the stenotic vessel, left ventricular function (ejection fraction ±5%), and size of SPECT perfusion defect. Patients with previous myocardial infarctions or coronary revascularization (<30 days), valvular heart disease, left bundle branch block, or cardiomyopathy were excluded from the analysis. Thus, 532 patients were included in the final study group.

Quantitative coronary angiography was performed in all patients in whom coronary lesions were defined by visual analysis. Analysis was performed using a computer-assisted automated edge detection system (Philips Easy Vision; Philips Medical Systems, Andover, Massachusetts). The investigator analyzing the angiograms was blinded to clinical and myocardial perfusion scintigraphic data. The guiding catheter was used as a scaling device. The minimal luminal diameter and the proximal and distal reference vessel diameters were determined to allow calculation of the percentage diameter stenosis. Significant coronary artery stenosis was defined as >50% diameter stenosis on quantitative coronary angiography.

Stress and rest studies were done in a 1-day (1 × 300 MBq followed by 1 × 750 MBq) or a 2-day (2 × 450 MBq) protocol using technetium-99m tetrofosmin or sestamibi. Three hundred thirty-four patients were stressed by exercise stress and 198 patients by pharmacologic stress using dipyridamole. In case of exercise stress, technetium-99m tetrofosmin or sestamibi was injected during maximal or symptom-limited exercise, with the workload increased by 25 W every 2 minutes and at rest. In case of dipyridamole stress, technetium-99m tetrofosmin or sestamibi was injected 3 minutes after the completion of a 4-minute dipyridamole infusion (0.56 mg dipyridamole/kg body weight) and at rest. The SPECT protocol usually started with the stress portion, followed by SPECT imaging at rest either the same day (1-day protocol, n = 244) or a few days later (2-day protocol, n = 288). Antianginal drugs were stopped on the day of the stress test, and β blockers were discontinued 2 days before the test. Acquisition was done in a 64 × 64 matrix using a Siemens MULTISPECT 3 triple-head gamma camera (Siemens Gammasonics, Inc., Hoffman Estates, Illinois) 60 minutes after tracer injection, with 60 views using a zoom factor of 1.23.

SPECT images were evaluated by visual and quantitative analysis. For visual analysis, myocardial technetium-99m sestamibi uptake was visually assessed on the short-axis and long-axis slices obtained at rest and peak stress. For quantitative analysis, using Quantitative Perfusion SPECT (Cedars-Sinai Medical Center, Los Angeles, California), the stress and rest data sets of all patients were analyzed in fully automatic operation mode. The summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) values were calculated on the basis of comparison with the corresponding gender-specific institutional normal database. The left ventricular myocardium was divided into 20 segments and scored for the extent and severity of perfusion abnormalities in each segment during stress and rest on a 5-point scale: 0 = normal, 1 = slight reduction, 2 = moderate reduction, 3 = severe reduction of radiotracer uptake, and 4 = no radiotracer uptake. The SSS and SRS are the sums of scores in these 20 segments. In case the segmental rest score had a higher value than the stress score, it was assigned the stress score value. The sum of the differences between each of the 20 segments on the stress and rest images was defined as the SDS, also called the reversibility score. It is an index of jeopardized myocardium.

In case of medical treatment, β receptor blockers and nitrates were administered to obtain a symptom-free condition. PCI was performed according to standard techniques. All patients were treated using bare-metal stents, which were standard devices at the time of the index procedure. Anticoagulation during PCI was accomplished with unfractionated heparin per standard protocol. Patients received glycoprotein IIb/IIIa receptor inhibitors according to usual protocol with abciximab or tirofiban at the discretion of the operator. All patients were treated with aspirin 100 mg/day before PCI and indefinitely afterward. Clopidogrel was given in a loading dose of 300 or 600 mg before PCI and continued at 75 mg/day for 4 weeks after PCI. The success of PCI as seen on angiography was defined as normal coronary artery flow and <20% stenosis in the luminal diameter after coronary stent implantation.

Clinical follow-up information on patient survival was obtained in all patients by dedicated research personnel. Data were obtained by telephone contact with the patients or with their immediate relatives and complemented by information obtained from the patients’ general physicians or charts from recurrent hospital admissions. In case neither patients nor relatives could be contacted and patients’ general physicians did not know about the patients’ outcomes, local population registries were contacted to obtain information about patients’ possible death or current locations. Patients were followed for ≥4.5 years (mean 6.4 ± 1.2) for hard events, defined as death, nonfatal myocardial infarction, and myocardial revascularization procedure. Myocardial infarction was verified by hospital documentation, and the diagnosis was based on the accepted criteria of characteristic chest pain and electrocardiographic and enzyme changes. In addition, a composite of death, nonfatal myocardial infarction, bypass surgery, or PCI was evaluated. Furthermore, using a standard medical questionnaire, the level of current limitations due to angina pectoris by Canadian Cardiovascular Society class and dyspnea by New York Heart Association class were determined at the end of the follow-up period.

Values are expressed as mean ± SD or as percentages. Categorical variables were compared using the chi-square test or Wilcoxon’s rank-sum test, and continuous variables were compared using Student’s t test. Estimates of the cumulative event rate were calculated using the Kaplan-Meier method, and the primary efficacy of PCI, compared to optimal medical therapy, was assessed using log-rank statistics. The effect of PCI, as measured by the hazard ratio and its associated 95% confidence interval, was estimated for the cumulative event rate using the Cox proportional-hazards model. Cox proportional-hazards analysis was performed to identify univariate and multivariate predictors of death and events during follow-up. Included variables were age, gender, treatment modality, severity of CAD, the left ventricular ejection fraction, SSS, and SRS. A p value <0.05 was considered statistically significant.

Results

A total of 532 patients were included in the analysis ( Table 1 ). In 524 of these patients (98%), clinical follow-up could be obtained. There were no differences between the PCI and medical treatment groups in age, gender, history of PCI, coronary bypass grafting, number of diseased coronary vessels, cardiac risk factors, and ejection fraction. In the medical group, more patients had histories of myocardial infarctions.

Results of quantitative coronary angiography are listed in Table 2 . Although the reference diameter was similar between the medical treatment group and the PCI group, the minimal luminal diameter was smaller in the PCI group compared to the medical treatment group. This resulted also in greater diameter stenosis in the PCI group. A mean of 1.1 ± 0.3 vessels were treated using PCI in the interventional treatment group.

Results of myocardial perfusion scintigraphy are listed in Table 3 . The frequency of scar was similar between the 2 groups. There were some differences in the distribution of ischemic areas. The overall extent of perfusion deficits at rest and with stress as defined by SSS, SRS, and SDS was not different between the 2 treatment groups.

Table 3

Stress and rest myocardial perfusion scintigraphy

Variable	Medical Treatment (n = 266)	PCI (n = 266)	p Value
Ischemia	100%	100%	1.000
Scar	62%	56%	0.132
Area of ischemia
Apex	18%	24%	0.083
Anterior	31%	40%	0.027
Septal	19%	22%	0.325
Inferior	28%	24%	0.290
Posterior	29%	33%	0.147
Lateral	23%	17%	0.070
Summed stress score	12.8 ± 9.5	14.0 ± 10.1	0.127
Summed rest score	7.7 ± 8.4	7.3 ± 8.6	0.554
Summed difference score	5.2 ± 3.6	6.7 ± 5.9	0.062

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