Myocardial viability: methods of assessment and clinical relevance

Myocardial hibernation is hypoperfused dysfunctional myocardium that has the potential to recover function after coronary revascularization. Although recovery of regional function after revascularization is the gold standard for assessing the diagnostic accuracy of various techniques, improvements of EF, symptoms, and survival are fundamental end points. Despite important differences in the markers of viability by positron-emission tomography, single-photon emission tomography, two-dimensional echocardiography, and magnetic resonance imaging, their positive and negative predictive values in nonrandomized studies are fairly comparable. Assessment of myocardial viability may be clinically important in many patients but especially in those with EF < 30% and congestive heart failure. The degree of improvement in EF after coronary revascularization depends on the extent of hibernation, the suitability of coronary structure for revascularization, the lack of perioperative infarction, the completeness of revascularization, and the long-term patency of grafts.

Dynamic planar myocardial perfusion imaging in patients with one-vessel disease with intracoronary injection of technetium 99m teboroxime during papaverine-induced coronary hyperemia

This study examined the imaging results and kinetics of technetium 99m teboroxime after its intracoronary injection during papaverine-induced coronary hyperemia in patients with one-vessel disease before and after coronary angioplasty. Thirteen patients with > or = 90% diameter stenosis of either the left anterior descending or the left circumflex coronary artery were included. Two patients were excluded because of ventricular tachycardia during papaverine injection in one patient and unsuccessful angioplasty in the second patient. One mCi of technetium 99m teboroxime was injected into the left main coronary artery during coronary hyperemia induced by intracoronary injection of papaverine. Dynamic acquisition in a frame mode (20 sec/frame) was performed for 5 minutes in the left anterior oblique projection with a multicrystal gamma camera before and after successful angioplasty. Ischemic:normal count ratio increased from 0.75 +/- 0.4 before to 1.00 +/- 0.50 after angioplasty (p < 0.1). The T 1/2 of teboroxime was 6.5 +/- 1.5 min in the normal zone and 7.2 +/- 1.9 min in the ischemic zone (p, NS). Perfusion defects were visible in the territory of the stenosed coronary artery in 9 of 11 patients before angioplasty and in 7 of 11 patients after angioplasty. The image quality was excellent in all studies. Thus this study shows that performing dynamic imaging with intracoronary injection of technetium 99m teboroxime is feasible. This technique may be useful to study the impact of angioplasty on coronary flow and tracer kinetics.

Comparison of left ventricular performance in healthy young women and men during exercise

BACKGROUND

Previous studies show sex-related differences in left ventricular (LV) response to exercise. It is not clear, however, whether these differences are also seen in younger healthy subjects.

METHODS AND RESULTS

This study examined the changes in LV performance during dynamic upright exercise in 11 healthy men and 19 healthy young women according to the Bruce protocol and an individualized ramp protocol. There were no significant differences between the two protocols for either men or women in heart rate, blood pressure, LV ejection fraction (EF) (measured by ambulatory nuclear detector), and measured oxygen consumption. The peak oxygen consumption was higher in men than in women (44 +/- 13 vs 36 +/- 9 ml/kg/min; p < 0.05), but the peak heart rate, systolic blood pressure, and EF were similar. The change in EF (from rest to exercise) was 19% +/- 8% in men and 19% +/- 11% in women with the Bruce protocol (difference not significant) and 26% +/- 9% in men and 19% +/- 6% in women with the ramp protocol (difference not significant). At peak exercise, both men and women showed an increase in end-diastolic volume (29% +/- 14% vs 23% +/- 11%; difference not significant) and a decrease in end-systolic volume (41% +/- 15% vs 43% +/- 21%) (difference not significant). The increase in cardiac output during exercise was due to an increase in heart rate and stroke volume in both men and women. At submaximal exercise, however, the decrease in end-systolic volume was less in women than in men (p < 0.05).

CONCLUSIONS

There are no sex-related differences in compensatory mechanism during dynamic exercise in healthy subjects. The changes in contractility and LV volume are not affected by the exercise protocol.

Prognostic value of simultaneous perfusion and function assessment using technetium-99m sestamibi

This study examines the prognostic value of simultaneous perfusion and function assessment in 412 patients. The exercise perfusion pattern was a stronger predictor of events (mostly acute nonfatal myocardial infarcts) than resting ejection fraction.

Early postoperative rise in defibrillation threshold in patients with nonthoracotomy defibrillation lead systems: attenuation with biphasic shock waveforms

INTRODUCTION

In patients with non-thoracotomy defibrillation lead (NTL) systems coupled with monophasic shock waveforms, the defibrillation threshold (DFT) rises early after implantation. There is little information regarding features predictive of the DFT rise, or DFT changes early after implantation of NTL systems coupled with biphasic shock waveforms.

METHODS AND RESULTS

DFT measurements were performed serially at implantation, prior to hospital discharge (mean 4 +/- 3 days), and at follow-up (mean 49 +/- 22 days) in 146 patients with an NTL system. Factors were assessed for association with a "clinically important" early postimplantation DFT rise, defined as a rise of > or = 2 energy steps (2 to 4 J per step; > or = 5 J total). A clinically important early postimplantation DFT rise occurred in 48 patients (33%). Univariate predictors of the rise included the monophasic shock waveform, the Medtronic Transvene lead system, the presence of a subcutaneous defibrillation patch, and the number of shocks delivered during the implantation procedure. However, the only independent predictor of a clinically important DFT rise was the monophasic shock waveform (F = 18, P < 0.001). For the monophasic patient group (n = 79), the incidence of a DFT rise was 53% (n = 42). For the biphasic patient group (n = 67), the incidence of a DFT rise was 9% (n = 6). The clinical characteristics of the monophasic and biphasic groups were not significantly different, nor were their DFTs at implantation. Among a subgroup of 18 consecutive patients who underwent serial DFT testing utilizing both monophasic and biphasic waveforms, the incidence of a clinically important DFT rise with monophasic (n = 9,50%) was higher than with biphasic shocks (n = 3,17%; P = 0.05).

CONCLUSION

NTL systems coupled with biphasic shock waveforms have an attenuated incidence of a clinically important DFT rise early after implantation, relative to patients with NTL systems coupled to monophasic waveforms.

Prognostic value of tomographic rest-redistribution thallium 201 imaging in medically treated patients with coronary artery disease and left ventricular dysfunction

BACKGROUND

Previous studies show that rest-redistribution thallium imaging is useful in the assessment of myocardial viability. The impact of such studies on patient outcome is not well defined. This study examined the prognostic value of tomographic rest-redistribution 201T1 imaging in 81 medically treated patients with coronary artery disease and left ventricular dysfunction.

METHODS AND RESULTS

Rest-redistribution single-photon emission computed tomographic images were obtained and analyzed quantitatively. The segmental thallium uptake (20 segments per patient) was interpreted as normal, reversible defect, mild to moderate fixed defect, or severe fixed defect. The thallium images were abnormal in 80 patients, with no redistribution (no ischemia) in 43 patients and redistribution (ischemia) in 38 patients. The left ventricular ejection fraction was 27% +/- 8% in patients with no redistribution and 26% +/- 7% in patients with redistribution (difference not significant). In patients with no ischemia, there were 7 +/- 5 severe fixed defects and 5 +/- 4 mild to moderate fixed defects per patient. In patients with ischemia there were 7 +/- 4 reversible defects, 3 +/- 3 mild to moderate fixed defects, and 5 +/- 4 severe fixed defects per patient. The number of any abnormal segments was 11 +/- 5 in patients with no ischemia and 14 +/- 4 in patients with ischemia (p = 0.03). During a mean follow-up of 31 +/- 24 months, there were 11 cardiac deaths in patients with no ischemia (26%) and 22 in patients with ischemia (58%); the survival rate was worse in patients with than without ischemia (p < 0.05). Multivariate Cox survival analysis on important clinical, angiographic, and thallium variables showed that the presence of redistribution was an independent predictor of death (x2 = 5; p = 0.03).

CONCLUSIONS

Patients with left ventricular dysfunction and redistribution on rest thallium imaging, a marker of hibernating myocardium, have a higher mortality rate with medical therapy than do patients with a comparable degree of left ventricular dysfunction but with fixed defects only. Thus observations similar to those made with positron emission tomography can be made in a much more straightforward, simple, and probably cost-effective manner with single-photon emission computed tomography.

Prediction of improvement in left ventricular function with iodine-123-IPPA after coronary revascularization

Iodine-123-phenylpentadecanoic acid (IPPA) is a synthetic fatty acid suitable for myocardial imaging. This study is the result of a Phase I/II trial to evaluate IPPA's ability to predict functional recovery in patients undergoing coronary revascularization.

METHODS

Twenty-three patients with documented coronary disease underwent sequential SPECT imaging with IPPA before and radionuclide ventriculography both before and 8 wk after revascularization. Software was developed to evaluate myocardial IPPA metabolism and to determine the fraction of the left ventricle with intermediate metabolism.

RESULTS

There was a significant correlation between initial IPPA uptake and final LVEF. The fractional area of the left ventricle demonstrating IPPA metabolism in the intermediate metabolic range was significantly higher in patients who demonstrated a 5% or greater increase in EF after revascularization (0.90 +/- 0.08 versus 0.78 +/- 0.17, p = 0.04). When only the patients who received complete revascularization were evaluated, there was a more significant difference (improved 0.92 +/- 0.05 versus 0.74 +/- 0.17, p = 0.011). Taking a lower limit of 1 s.d. from the mean, (87%) the six patients who had > or = 5% increase in LVEF after revascularization had more than 87% of the left ventricle in the intermediate metabolic range, whereas seven of ten patients whose change in LVEF was < 5% had less than 87% in the intermediate metabolic range (p = 0.011).

CONCLUSION

In this initial experience, the amount of myocardium in the intermediate metabolic range is associated with improvement in LVEF after revascularization, especially in patients receiving complete revascularization.

Use of a tantalum-178 generator and a multiwire gamma camera to study the effect of the Mueller maneuver on left ventricular performance: comparison to hemodynamics and single photon emission computed tomography perfusion patterns

During the Mueller maneuver, there is a decrease in intrathoracic pressure and an increase in transmural left ventricular pressure. The changes in loading conditions cause transient left ventricular dysfunction. This study examined the effects of the Mueller maneuver on left ventricular performance using tantalum (Ta)-178 (half-life 9.3 min) and a multiwire gamma camera. First-pass radionuclide angiograms were obtained at baseline and during Mueller maneuver in 41 patients aged 58 +/- 10 years. In 34 patients, stress single photon emission computed tomography (SPECT) myocardial perfusion imaging with thallium-201 or sestamibi was also performed. Hemodynamic measurements during the Mueller maneuver (n = 10) showed a decrease in systemic pressure (139 +/- 25 mm Hg vs 123 +/- 24 mm Hg, p < 0.001) and pulmonary artery pressure (24 +/- 6 mm Hg vs 14 +/- 12 mm Hg, p = 0.01) and an increase in heart rate (67 +/- 10 bpm vs 75 +/- 14 beats/min, p = 0.001). Among the 34 patients who had perfusion imaging, the left ventricular ejection fraction remained unchanged or increased in 17 patients (group 1) (48% +/- 19% vs 49% +/- 21%, p not significant) and decreased (> or = 5%) in 17 patients (group 2) (55% +/- 13% vs 40% +/- 16%, p = 0.001). The stress SPECT images showed no or only fixed defects in 11 (65%) patients in group 1 and 3 (18%) patients in group 2 (p = 0.02), and reversible defects in 6 (35%) patients in group 1 and 14 (82%) patients in group 2 (p = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Implications of increased lung thallium uptake during exercise single photon emission computed tomography imaging

Increased lung thallium uptake during exercise is an important marker of patients who are at high risk and have CAD; however, most previous studies were done with planar imaging, and therefore it is unclear whether this conclusion is also true with SPECT imaging. This study examined the lung thallium uptake during exercise SPECT imaging in 1031 patients who also underwent coronary angiography. The lung thallium uptake was increased in 309 patients (group 1) and normal in 722 patients (group 2). Compared with patients in group 2, those in group 1 had more ST segment depression (44% vs 28%, p = 0.01), previous Q-wave myocardial infarction (28% vs 17%, p = 0.0001), larger perfusion defects (24% +/- 11% vs 10% +/- 11%, p = 0.0001), and multivessel CAD by angiography (75% vs 47%, p = 0.0001). Multivariate discriminant analysis identified left ventricular dilation, reversible defects, the size of perfusion abnormality, and the extent of CAD as independent predictors of increased lung thallium uptake. Increased lung thallium uptake was more common in men than women regardless of the extent of CAD: 26% versus 11% in patients with one-vessel, 38% versus 18% in patients with two-vessel, and 51% versus 31% in patients with three-vessel disease (p < 0.001 each). Thus increased lung thallium uptake by SPECT identifies patients with more severe anatomic and functional evidence of CAD. The sex-related difference suggests the need for a sex-specific normal file for quantitative analysis.

Spectroscopic analysis of Tm(3+) in PbO-Bi(2)O(3)-Ga(2)O(3) glass

Tm(3+)-doped heavy metal oxide glasses in the PbO-Bi(2)O(3)-Ga(2)O(3) system were prepared, and their emission characteristics were examined. Three emission bands at the infrared wavelength region were observed, at 1.46, 1.79, and 2.36 µm, which are associated with the (3)H(4) ? (3)F(4), (3)F(4) ? (3)H(6), and (3)H(4) ? (3)H(5), transitions, respectively. Measured fluorescence lifetimes for the first two transitions were 0.160 and 1.035 ms, respectively. Oscillator strengths and intensity parameters suggest that the ionicity of Tm-Obonds in the glass is higher when compared with those in other oxide glass hosts. Higher radiative transition probabilities of the three infrared emissions than those calculated for other glasses appear to provide potentials for future laser applications.

Results of adenosine single photon emission computed tomography thallium-201 imaging in hemodynamic nonresponders

Systolic blood pressure typically decreases during adenosine infusion because of stimulation of A2b receptors, resulting in systemic vasodilation. This study examined the results of adenosine single photon emission computed tomography (SPECT) thallium-201 imaging in patients who did not show such a decrease in blood pressure during peak adenosine effect (nonresponders). The 102 nonresponders and 341 responders had no significant differences in age, gender, history of diabetes mellitus, hypertension, or previous myocardial infarction. The extent of coronary artery disease (CAD) by angiography was also similar. The sensitivity of SPECT thallium-201 imaging in patients with one-vessel disease was 82% in nonresponders and 84% in responders (p value not significant [NS]); in patients with multivessel disease, it was 90% in nonresponders and 94% in responders (p = NS) and for all CAD, it was 87% in non-responders and 91% in responders (p = NS). Thus lack of hemodynamic systemic response during adenosine infusion does not affect sensitivity for detecting CAD.

Impact on exercise single-photon emission computed tomographic thallium imaging on patient management and outcome

BACKGROUND

Stress perfusion imaging is useful in risk stratification of patients with known or suspected coronary artery disease. In the current era of managed health care, there is a need to provide data on patient outcome.

METHODS AND RESULTS

This study examined the impact of exercise single-photon emission computed tomographic (SPECT) thallium imaging on patient management (the subsequent need for coronary angiography and revascularization) and outcome (the occurrence of hard cardiac events defined as cardiac death or nonfatal acute myocardial infarction) in 2700 patients who were being evaluated for diagnostic purposes. None of the patients had previous coronary angiography, coronary revascularization, or Q-wave myocardial infarction. The SPECT images were normal in 2027 patients (group 1) and abnormal in 673 patients (group 2). Within 6 months after thallium imaging 53 patients in group 1 (3%) and 242 patients in group 2 (36%) underwent coronary angiography (p = 0.0001). The patients who underwent coronary angiography had higher pretest probability of coronary disease (group 1) or more perfusion defects (group 2) than patients who did not (p = 0.0001 each). Coronary revascularization within 3 months of coronary angiography was performed in 1 of the 53 patients (2%) in group 1 and in 87 of 242 patients (30%) in group 2 (p = 0.0001). Among the remaining patients who had coronary angiography but were medically treated there were no hard cardiac events in group 1 but there were 15 events in group 2 (p = 0.02).

CONCLUSIONS

The results of exercise SPECT thallium imaging are important in patient management and outcome. Coronary angiography, coronary revascularization and events are rare in patients with normal exercise SPECT thallium images.

Circadian variation of ventricular arrhythmia recurrences after cardioverter-defibrillator implantation in patients with healed myocardial infarcts

Past studies using Holter monitoring and retrospective reviews of death certificates have documented peak occurrence of sudden death and nonsustained ventricular tachycardia (VT) in the morning hours. We used the Ventritex Cadence device (Ventritex, Sunnyvale, California) which documents the date and time of all stored arrhythmias leading to device therapy to evaluate the circadian pattern of sustained ventricular arrhythmia recurrence. Mean follow-up after defibrillator implantation was 628 +/- 285 days. All 390 patients had at least 1 episode (range 1 to 43) of sustained VT documented from analysis of the stored electrograms associated with an arrhythmia event. Stored electrograms were available for review and analysis in 3,041 device detections; 349 stored events were excluded because they did not fulfill the diagnostic criteria for VT or failed to document the onset of the ventricular arrhythmia at the beginning of the recorded event of the arrhythmia episode. Criteria for the diagnosis of VT or ventricular fibrillation were met in 2,692 arrhythmia episodes occurring in 390 patients. There was circadian variation for ventricular arrhythmia recurrence for the whole patient group with the data fit to the sinusoidal density function: f(t) = 126 - 51 x cos (-57 + 2 pi t/24) - 25 x sin (63 + 2 pi t/12) (p < 0.0001). Ventricular arrhythmia occurrence rate was lowest between 2:00 and 3:00 A.M., and highest between 10:00 and 11:00 A.M. In addition, the same circadian pattern was demonstrated regardless of patient age, gender, left ventricular ejection fraction (< 35% or > or = 35%), and VT cycle length (< 300 or > or = 300 ms).(ABSTRACT TRUNCATED AT 250 WORDS)

Prognostic value of rest-redistribution tomographic thallium-201 imaging in ischemic cardiomyopathy

The relation between the presence of viable myocardium by rest-redistribution thallium imaging and prognosis is not well defined. This study examined the prognostic value of rest-redistribution single-photon emission computed tomographic imaging with thallium-201 in patients with coronary artery disease (CAD) and left ventricular (LV) dysfunction. Patients were divided into 2 groups: group 1 patients (n = 47) were treated medically and group 2 patients (n = 38) underwent coronary revascularization. The 2 groups were comparable in the extent of CAD and in LV ejection fraction. Thallium images showed normal tracer uptake in 1 group 1 and 3 group 2 patients, fixed defects in 26 group 1 and 18 group 2 patients, and both reversible and fixed defects in 20 group 1 and 17 group 2 patients (p = NS). Based on analysis of 20 segments/patient, reversible defects were seen in 4 +/- 4 segments/patient in group 1 and 5 +/- 5 segments/patient in group 2 (p = NS). Viable myocardium (defined as normal tracer uptake, reversible defects, or mild fixed defects) was seen in 14 +/- 4 segments/patient in group 1 and 15 +/- 5 segments/patient in group 2 (p = NS). During a mean follow-up of 31 months, there were 16 group 1 (34%) and 6 group 2 (16%) deaths. The annual mortality rate was 13% in group 1 and 6% in group 2. Actuarial survival analysis showed better survival in group 2 than in group 1 (p = 0.056). Thus, viable myocardium in patients with CAD and LV dysfunction is associated with poor prognosis with medical therapy. Coronary revascularization improves prognosis.

Optimizing patient selection for coronary angiography

Indications for coronary angiography depend on the patient's clinical presentation. In many situations, coronary angiography may be reserved for patients who have severe symptoms, despite optimal medical therapy, and for patients defined to be at high risk, based on noninvasive stress testing. These patient groups include those with chest pain syndromes, postmyocardial infarction, unstable angina, postcoronary revascularization, severe left ventricular dysfunction, survivors of sudden cardiac death, and those about to undergo major vascular noncardiac surgery.

Relation between diastolic left ventricular function and myocardial blood volume during adenosine-induced coronary hyperemia

Adenosine infusion is accompanied by increases in coronary blood flow and myocardial blood volume. Myocardial blood volume may produce changes in diastolic left ventricular (LV) performance by increasing myocardial turgor. Diastolic dysfunction may also be the result of myocardial ischemia. The relation between changes in LV mass and diastolic function has not been previously investigated. This study examined the relation between changes in LV mass during adenosine-induced coronary hyperemia and LV diastolic function. Serial two-dimensional and Doppler echocardiographic measurements were made before, during, and after adenosine infusion (140 micrograms/min for 6 min) in 21 patients with (group 1) and 10 patients without (group 2) coronary artery disease (CAD). The LV mass and transmitral diastolic filling indexes were determined from digitized images from apical four-chamber view. Adenosine infusion produced a greater increase in LV mass in group 2 than in group 1 (29% +/- 11% vs 9% +/- 6%, p < 0.0002). The ratio of transmitral early (E) to atrial (A) filling velocity (E/A) increased 10% +/- 16% in group 2 and decreased 8% +/- 20% in group 1 (p < 0.02), and the velocity time integral of early filling increased 11% +/- 52% in group 2 and decreased 20% +/- 31% in group 1 (p < 0.04). There was a correlation between the change in E/A ratio and the LV mass (r = 0.53, p < 0.003). Thus adenosine infusion caused a greater increase in LV mass in normal subjects than in patients with CAD. There were also changes in Doppler-derived indexes of diastolic LV function.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of thallium-201 single-photon emission computed tomography and electrocardiographic response during exercise in patients with normal rest electrocardiographic results

OBJECTIVES

This study compared the diagnostic accuracy of exercise thallium-201 single-photon emission computed tomography (SPECT) with the exercise electrocardiographic (ECG) response in patients with normal baseline ECG results.

BACKGROUND

Previous studies comparing exercise thallium imaging with exercise electrocardiography have included patients with abnormal rest ECG results that may have biased the results in favor of thallium imaging.

METHODS

Of 321 patients with a pretest likelihood of coronary artery disease of 70 +/- 29% (mean +/- SD) who underwent exercise stress testing and coronary angiography, 68 had no coronary artery disease; 94 had one-vessel disease; 79 had two-vessel disease; and 80 had three-vessel or left main coronary artery disease.

RESULTS

The diagnostic accuracy of SPECT was higher than that of the ECG response (79% vs. 49%, p < 0.0001). Patients with extensive (left main or three-vessel) coronary artery disease were older and had a lower work load, lower heart rate, greater ST segment depression and more extensive perfusion abnormalities than patients with no disease or one- or two-vessel disease. Multivariate discriminant analysis of exercise and thallium variables identified multivessel thallium abnormalities (F = 35), exercise heart rate (F = 18) and extent of ST segment depression (F = 6) as independent predictors of extensive disease. Of the 80 patients with left main or three-vessel disease, 37 (46%) had > or = 2-mm ST segment depression, 44 (55%) had multivessel SPECT abnormalities, and 61 (76%) had either > or = 2-mm ST depression or multivessel SPECT abnormalities (p = 0.0005 vs. the ECG response; p = 0.01 vs. SPECT).

CONCLUSIONS

In patients with an intermediate to high pretest probability of coronary artery disease and normal baseline ECG results, SPECT is superior to the ECG response in detecting coronary disease. Further, SPECT provides incremental power in identifying patients with extensive (left main or three-vessel) coronary disease.

Assessment of myocardial viability by dynamic tomographic iodine 123 iodophenylpentadecanoic acid imaging: comparison with rest-redistribution thallium 201 imaging

BACKGROUND

This study examined the ability of dynamic 123I-labeled iodophenylpentadecanoic acid (IPPA) imaging to detect myocardial viability in patients with left ventricular (LV) dysfunction caused by coronary artery disease.

METHODS AND RESULTS

Serial 180-degree single-photon emission computed tomographic (SPECT) images (five sets, 8 minutes each) were obtained starting 4 minutes after injection of 2 to 6 mCi 123I at rest in 21 patients with LV dysfunction (ejection fraction [EF] 34% +/- 11%). The segmental uptake was compared with that of rest-redistribution 201Tl images (20 segments/study). The number of perfusion defects (reversible and fixed) was similar by IPPA and thallium (11 +/- 5 vs 10 +/- 5 segments/patient; difference not significant). There was agreement between IPPA and thallium for presence or absence (kappa = 0.78 +/- 0.03) and nature (reversible, mild fixed, or severe fixed) of perfusion defects (kappa = 0.54 +/- 0.04). However, there were more reversible IPPA defects than reversible thallium defects (7 +/- 4 vs 3 +/- 4 segments/patient; p = 0.001). In 14 patients the EF (by gated pool imaging) improved after coronary revascularization from 33% +/- 11% to 39% +/- 12% (p = 0.002). The number of reversible IPPA defects was greater in the seven patients who had improvement in EF than in the patients without such improvement (10 +/- 4 vs 5 +/- 4 segments/patient; p = 0.075).

CONCLUSIONS

123I-labeled IPPA SPECT imaging is a promising new technique for assessment of viability. Reversible defects predict recovery of LV dysfunction after coronary revascularization.

Independent and incremental prognostic value of exercise thallium single-photon emission computed tomographic imaging in women

BACKGROUND

This study examined the independent and incremental prognostic value of exercise thallium single-photon emission computed tomographic imaging in 212 women who also underwent coronary angiography.

METHODS AND RESULTS

The left ventricular ejection fraction was normal (65% +/- 15%). During a mean follow-up of 40 months, 27 women had events (cardiac death or nonfatal myocardial infarction). Univariate Cox survival analysis showed several variables to be different between patients with events and those without events: age, exercise heart rate, the extent of coronary artery disease, reversible thallium defects, number of segments with reversible abnormality, and size of perfusion abnormality. Multivariate survival analysis showed that a large perfusion abnormality and age were the independent predictors of events. Actuarial life-table analysis showed that women with a large thallium abnormality (> or = 15% of the myocardium) had significantly worse event-free survival rates than had women with no or small abnormalities (Mantel-Cox statistic = 16; p = 0.0001).

CONCLUSIONS

Thus exercise thallium-201 single-photon emission computed tomographic imaging provides independent and incremental prognostic information to clinical, exercise, and coronary angiographic results in women. The presence of a larger thallium abnormality identifies women at high risk of cardiac events.