Technetium 99m sestamibi myocardial perfusion imaging predicts clinical outcome in the community outpatient setting. The Nuclear Utility in the Community (NUC) Study

The value of multi-slice-computed tomography coronary angiography for risk stratification

Multi-slice-computed tomography coronary angiography (CTA) provides direct non-invasive anatomic assessment of the coronary arteries allowing for early identification of coronary artery disease (CAD). This information is useful for diagnosis of CAD, particularly the rule out of CAD. In addition, early identification of CAD with CTA may also be useful for risk stratification. The purpose of this review is to provide an overview of the current literature on the prognostic value of CTA and to discuss how the prognostic information obtained with CTA can be used to further integrate the technique into clinical practice. Non-invasive anatomic assessment of plaque burden, location, composition, and remodeling using CTA may provide prognostically relevant information. This information has been shown to be incremental to the Framingham risk score, coronary artery calcium scoring, and myocardial perfusion imaging. Characterization of atherosclerosis non-invasively has the potential to provide important prognostic information enabling a more patient-tailored approach to disease management.Future studies assessing outcome after CTA-based risk adjustments are needed to further understand the value of detailed non-invasive anatomic imaging.

Effects of a cognitive stress challenge on myocardial perfusion and plasma cortisol in coronary heart disease patients with depression

Although it is well established that coronary heart disease (CHD) patients with depression exhibit increased mortality compared with equally ill cardiac patients without depression, the mechanisms mediating this effect remain obscure. Depression is characterized by vulnerability to stress and heightened stress responsiveness, and stress can theoretically act through several biological pathways to contribute to excess mortality from CHD. Mechanisms connecting stress, depression and cardiovascular mortality have not been previously explored in detail. The purpose of this study was to assess the effects of stress and depression on myocardial perfusion and plasma cortisol concentrations in CHD patients. Patients with CHD with and without depression (n = 28) underwent single photon emission computed tomography imaging of myocardial perfusion at rest and during a stressful cognitive challenge. Severity of ischaemia was measured by summing perfusion defect scores across myocardial segments and subtracting out rest from stress scores. Plasma cortisol concentrations were measured at baseline and in response to the stressful challenge. There were no differences in stress-induced myocardial ischaemia or plasma cortisol response to stress between CHD patients with and without depression. Depressed CHD patients with a history of psychological trauma (n = 5) had an increase in stress-induced ischaemia scores [7; standard deviation (SD) = 5] compared with CHD patients with depression without a history of psychological trauma (2 SD = 2) and CHD patients without depression or psychological trauma (1; SD = 2) (F = 8.51; degree of freedom = 2,23; p = 0.007). Eighty per cent of CHD/depression trauma-exposed subjects had stress-induced ischaemia as opposed to 38 per cent of CHD/depression subjects without trauma exposure and 23 per cent of subjects with CHD without depression or trauma. Self-reported nervousness during the cognitive stressor was correlated with stress-induced ischaemia. These preliminary findings suggest that depression with a history of prior exposure to traumatic stress is associated with increased risk for stress-induced cardiovascular ischaemia.

Prospective evaluation of the impact of diabetes and left ventricular hypertrophy on the relationship between ischemia and transient ischemic dilation of the left ventricle on single-day adenosine Tc-99m myocardial perfusion imaging

BACKGROUND

Diabetes and left ventricular hypertrophy (LVH) can cause coronary flow reserve abnormalities in the absence of coronary artery disease (CAD). We sought to evaluate the impact of LVH and diabetes on the relationship between ischemia, severe CAD, and transient ischemic dilation (TID) on adenosine myocardial perfusion imaging (MPI).

METHODS AND RESULTS

We prospectively recruited 157 patients referred for routine single-day adenosine technetium 99m MPI. LVH was assessed by use of transthoracic echocardiography. A ratio of 1.19 or greater on MPI defined TID in men and 1.31 or greater in women. Summed difference scores were determined by use of a 17-segment 5-point scoring system. TID was present in 22 of 157 patients (14%), diabetes in 54 of 157 (34%), and LVH in 42 of 157 (27%). By multivariate logistic regression, LVH, ischemia (summed difference score >2), and diabetes were independently predictive of TID. The incidence of TID was stratified by the presence or absence of diabetes and/or LVH in those with ischemia on MPI (8/8 [100%] vs 0/11 [0%], P < .002) or severe CAD on angiography (5/7 [71%] vs 0/8 [0%], P < .01). All those with TID (22/22 [100%]) had either diabetes or LVH (or both).

CONCLUSION

Although this study confirms the association between TID and both ischemia and severe CAD, all patients with TID had diabetes, LVH, or frequently, both, suggesting that the pathophysiology of these disease processes may play an integral role in the manifestation of TID on adenosine MPI.

[Study of efficacy and safety of pharmacological stress tests in nuclear cardiology]

BACKGROUND/AIM

Treadmill test combined with myocardial perfusion scintigraphy (MPS) is a commonly used technique in the assessment of coronary artery disease. Many patients who cannot adequately perform exercise stress testing may nevertheless undergo pharmacological tests, most commonly with the vasodilator agents (adenosine and dipyridamole), as well as the positive inotropic agent dobutamine. Patients undergoing vasodilators stress testing with either dipyridamole or adenosine also perform simultaneous low-intensity exercise. The aim of this study was to compare various pharmacological stress tests alone or in combination with low intensity exercise as preparation for MPS in regard to incidence of adverse effects, quality of diagnostic image and the acquisition initial time.

METHODS

A total of 2 205 patients underwent pharmacological stress tests. Pharmacological stress test with adenosine was applied in 493 patients. In 405 of them we performed concomitant low level exercise (50 W) by bicycle ergometar (AdenoEX). In 88 of them we performed adenosine abbreviated protocol (AdenoSCAN). In 1 526 patients we performed pharmacological stress test with dipyridamole. In 871 of them we performed concomitant low level exercise (50 W) by bicycle ergometar (DipyEX), and in 775 we used only dipyridamole protocol (DipySCAN). In 186 patients we used pharmacological stress test with dobutamine. We followed side effects of adenosine, dipyiridamole and dobutamine, compared results between protocols with concomitant low level exercise and vasodilatators only. We also compared image quality, and suggested time of acquisition after stress test.

RESULTS

We found numerous side effects especially with adenosine, but these effects were short-lived and not required active interventions. Benefit with concomitant exercise in booth AdenoEX and DipyEX included decreased side effects (AdenoEX vs AdenoSCAN 620% vs 87%, respectively, and DipyEX vs DipySCAN 37% vs 59%, respectively) improved safety and patients tolerance, improved target-to-background ratios because of less subdiaphragmal activity, and earlier acquisition time. Because of producing a lot of arrhythmias (in 49% of patients) dobutamin was considered a last choice for pharmacological stress testing.

CONCLUSION

Safety and efficacy of vasodilatators (adenosine, dipyridamole) pharmacological stress tests are good, but with concomitant exercise even better. The safety and efficacy of adenosin are better than those of dipyridamole. AdenoEX protocol provides good safety and patients tolerancy. In light of these benefits we recommend AdenoEX whenever possible. Dobutamine is the last pharmacological toll for MPS.

The RegEx trial: a randomized, double-blind, placebo- and active-controlled pilot study combining regadenoson, a selective A(2A) adenosine agonist, with low-level exercise, in patients undergoing myocardial perfusion imaging

BACKGROUND

Although vasodilator stress myocardial perfusion imaging (MPI) is increasingly performed with exercise, adenosine A(2A) receptor agonists have not been studied with exercise.

OBJECTIVES

To determine the safety of administering regadenoson during exercise and, secondarily, to evaluate image quality, patient acceptance, and detection of perfusion defects.

METHODS

Patients requiring pharmacologic MPI received a standard adenosine-supine protocol (AdenoSup, n = 60) and were then randomized (2:1) in a double-blind manner to low-level exercise with bolus intravenous injection of regadenoson (RegEx, n = 39) or placebo (PlcEx, n = 21).

RESULTS

Adverse events occurred in 95%, 77%, and 33% of patients receiving AdenoSup, RegEx, and PlcEx, respectively. Peak heart rate was 13 beats per minute (bpm) and 21 bpm greater following RegEx compared to that following PlcEx and AdenoSup, respectively (P = .006 and <.001). Change from baseline in mean systolic blood pressure (SBP), change from baseline to nadir SBP, and percentage of patients with a decline in SBP by > or = 20 mm Hg showed no important differences between RegEx and PlcEx. No occurrences of 2nd degree or higher AV block were observed following RegEx or PlcEx; one patient developed 2nd degree AV block following AdenoSup. The mean heart-to-liver and heart-to-gut ratios were improved on RegEx vs AdenoSup: 0.85 (0.34) vs 0.65 (0.26), P < .001 and 1.1 (0.36) vs 0.97 (0.34), P < .001, respectively. Compared to AdenoSup, 70% of patients felt RegEx was much or somewhat better.

CONCLUSIONS

Combining regadenoson with low-level exercise is feasible, well tolerated, and associated with fewer side effects compared to AdenoSup.

Delayed heart rate recovery after adenosine stress testing with supplemental arm exercise predicts mortality

BACKGROUND

Delayed heart rate (HR) recovery after treadmill exercise testing predicts mortality. Patients with suspected ischemic heart disease who cannot perform adequate treadmill exercise are typically evaluated with pharmacological stress myocardial perfusion imaging (MPI) studies, but little prognostic significance has been attributed to the hemodynamic response to vasodilator stress testing with low-level exercise. We hypothesized that a delay in HR recovery after adenosine stress testing with arm exercise is associated with increased mortality.

METHODS AND RESULTS

Technetium 99m-Sestamibi MPI was performed in 1,455 consecutive patients (70 +/- 12 years, 50.2% men) with adenosine stress and supplemental arm exercise. HRs were recorded at rest, continuously during infusion, and then 5 minutes post-infusion. Delayed HR recovery was defined as a decline of < or = 12 bpm from peak HR at 5 minutes after discontinuation of the infusion. Of 1,356 patients during 5 years of follow up, there were 135 deaths (10%). Delayed HR recovery was strongly predictive of all-cause mortality (16.5% vs 5.3% in those with normal HR recovery, P < .001) with an adjusted hazard ratio of 2.5 (95% CI, 1.7-3.6; P < .001).

CONCLUSION

Delayed HR recovery after adenosine stress testing with arm exercise is a readily available and powerful predictor of all-cause mortality.

Non-invasive cardiac imaging techniques and vascular tools for the assessment of cardiovascular disease in type 2 diabetes mellitus

Cardiovascular disease is the major cause of mortality in type 2 diabetes mellitus. The criteria for the selection of those asymptomatic patients with type 2 diabetes who should undergo cardiac screening and the therapeutic consequences of screening remain controversial. Non-invasive techniques as markers of atherosclerosis and myocardial ischaemia may aid risk stratification and the implementation of tailored therapy for the patient with type 2 diabetes. In the present article we review the literature on the implementation of non-invasive vascular tools and cardiac imaging techniques in this patient group. The value of these techniques as endpoints in clinical trials and as risk estimators in asymptomatic diabetic patients is discussed. Carotid intima-media thickness, arterial stiffness and flow-mediated dilation are abnormal long before the onset of type 2 diabetes. These vascular tools are therefore most likely to be useful for the identification of 'at risk' patients during the early stages of atherosclerotic disease. The additional value of these tools in risk stratification and tailored therapy in type 2 diabetes remains to be proven. Cardiac imaging techniques are more justified in individuals with a strong clinical suspicion of advanced coronary heart disease (CHD). Asymptomatic myocardial ischaemia can be detected by stress echocardiography and myocardial perfusion imaging. The more recently developed non-invasive multi-slice computed tomography angiography is recommended for exclusion of CHD, and can therefore be used to screen asymptomatic patients with type 2 diabetes, but has the associated disadvantages of high radiation exposure and costs. Therefore, we propose an algorithm for the screening of asymptomatic diabetic patients, the first step of which consists of coronary artery calcium score assessment and exercise ECG.

[Adenosine stress protocols for myocardial perfusion imaging]

BACKGROUND/AIM

Treadmill test combined with myocardial perfusion scintigraphy (MPS) is a commonly used technique in the assessment of coronary artery disease. There are many patients, however, who may not be able to undergo treadmill test. Such patients would benefit from pharmacological stress procedures combined with MPS. The most commonly used pharmacological agents for cardiac stress are coronary vasodilatators (adenosine, dipyridamol) and catecholamines. Concomitant low-level treadmill exercise with adenosine pharma cologic stress (AdenoEX) during MPS has become commonly used in recent years. A number of studies have demonstrated a beneficial impact of AdenoEX protocol. The aim of the study was, besides introducing into practice the two types of protocols of pharmatological stress test with adenosine, as a preparation for MPS, to compare and monitor the frequency of their side effects to quality, acquisition, as well as to standardize the onset time of acquisition (diagnostic imaging) for both protocols.

METHODS

A total of 130 patients underwent pharmacological stress test with adenosine (vasodilatator). In 108 of the patients we performed concomitant exercise (AdenoEX) of low level (50W) by a bicycle ergometar. In 28 of the patients we performed Adenosine ab breviated protocol (AdenoSCAN). Side effects of adenosine were followed and compared between the two kinds of protocols AdenoEX and AdenoSCAN. Also compared were image quality and suggested time of acquisition after the stress test.

RESULTS

Numerous side effects were found, but being short lived they did not require any active interventions. The benefit of AdenoEX versus AdenoSCAN included decreased side effects (62% vs 87%), improved safety and patients tolerance, improved target-to-background ratios because of less subdiaphragmatic activity, earlier acquisition, and improved sensitivity.

CONCLUSION

The safety and efficacy of adenosine pharmacological stress is even better with concomitant exercise. In the light of these benefits we recommend AdenoEX whenever possible.

Symptom-limited exercise combined with dipyridamole stress: prognostic value in assessment of known or suspected coronary artery disease by use of gated SPECT imaging

BACKGROUND

Combining vasodilator and exercise stress reduces noncardiac side effects, improves image quality, and enhances the detection of ischemia, compared with suboptimal exercise or vasodilator stress alone. However, prognostic data with combined protocols are limited.

METHODS AND RESULTS

Consecutive patients (n = 2064) who underwent symptom-limited exercise and dipyridamole stress with gated single-photon emission computed tomography (SPECT) imaging, without early revascularization, were studied. Subsequent cardiac death or nonfatal myocardial infarction was related to exercise and gated SPECT variables. Cox proportional hazards regression modeling was performed to identify predictors of adverse outcome. Annualized event rates in patients with normal and abnormal images were 0.96% and 2.71%, respectively (P < .001). With abnormal imaging, annualized event rates were 0.86% and 3.13% in patients with average to high and fair or poor functional capacity, respectively (P = .019). Abnormal imaging, a severely reduced post-stress ejection fraction, transient ischemic dilation, and fair or poor functional capacity emerged as predictors of adverse outcome. Accordingly, patients were stratified into low-risk, intermediate-risk, and high-risk cohorts with annualized event rates of 0.94%, 2.24%, and 8.19%, respectively (P < .001 in any two-way comparison).

CONCLUSIONS

A protocol that combines symptom-limited exercise and dipyridamole stress with gated SPECT imaging provides highly effective risk stratification for adverse outcomes.

The expanding role of left ventricular functional assessment using gated myocardial perfusion SPECT: the supporting actor is stealing the scene

BACKGROUND

Gating of single-photon emission computed tomography (SPECT) has significantly improved the reliability and diagnostic accuracy of myocardial perfusion imaging. The functional parameters derived from this technique, mainly left ventricular volumes and ejection fraction, have been demonstrated to be accurate and reproducible. They are able to increase the detection of severe and extensive coronary artery disease and show a significant incremental prognostic power over perfusion abnormalities. Therefore, the importance given to gated SPECT functional data has progressively grown.

DISCUSSION

This circumstance has further expanded the indications for myocardial perfusion imaging and strengthened its position among the different imaging modalities. Moreover, several studies show that the evaluation of ventricular function may have a leading part in justifying the execution of perfusion scintigraphy in various clinical conditions.

AIM

Aim of this review is to describe this evolution of gated SPECT functional assessment from a supporting rank with respect to perfusion, to a main actor position in the field of cardiac imaging.

Subendocardial versus transmural ischaemia in myocardial perfusion SPECT--a Monte Carlo study

Myocardial perfusion imaging with single-photon emission computed tomography (SPECT) is useful for the evaluation of patients with known or suspected coronary artery disease. Parameters of interest are the reduction in the blood perfusion (severity) and the lesion volume (extent). The aim of this study was to evaluate these parameters, as calculated by automatic quantification software, for different cases of subendocardial and transmural myocardial lesions.

METHODS

A computer phantom was used to simulate 32 male patients with different defect locations and activity uptakes, which were based on clinical patient studies. The Monte Carlo program SIMIND was used to simulate realistic SPECT projections which were reconstructed to give short-axis images, analysed by the AutoQUANT program using the same procedure as for a real patient.

RESULTS

The results showed a disparity between the quantification of transmural and subendocardial lesions with the same lesion activity uptake reduction and this could be confirmed by visual interpretation. Neither the parameters given by the quantification program nor visual interpretation could distinguish between the transmural lesions and the subendocardial lesions with activity uptake reduction twice as high as in the corresponding transmural lesions.

CONCLUSION

Transmural lesions and the corresponding subendocardial lesions with the same activity uptake reduction could be separated by the quantification software for SPECT imaging and visual analysis. The subendocardial lesions with activity uptake reduction twice as high as in the corresponding transmural lesions could not be differentiated neither by the quantification software nor by visual interpretation. Thus these lesions will get the same scoring when analysed by the AutoQUANT program.

The Prognostic Value of Normal Exercise Myocardial Perfusion Imaging and Exercise Echocardiography

OBJECTIVES

The purpose of this work was to determine the prognostic value of normal exercise myocardial perfusion imaging (MPI) tests and exercise echocardiography tests, and to determine the prognostic value of these imaging modalities in women and men.

BACKGROUND

Exercise MPI and exercise echocardiography provide prognostic information that is useful in the risk stratification of patients with suspected coronary artery disease (CAD).

METHODS

We searched the PubMed, Cochrane, and DARE databases between January 1990 and May 2005, and reviewed bibliographies of articles obtained. We included prospective cohort studies of subjects who underwent exercise MPI or exercise echocardiography for known or suspected CAD, and provided data on primary outcomes of myocardial infarction (MI) and cardiac death with at least 3 months of follow-up. Secondary outcomes (unstable angina, revascularization procedures) were abstracted if provided. Studies performed exclusively in patients with CAD were excluded.

RESULTS

The negative predictive value (NPV) for MI and cardiac death was 98.8% (95% confidence interval [CI] 98.5 to 99.0) over 36 months of follow-up for MPI, and 98.4% (95% CI 97.9 to 98.9) over 33 months for echocardiography. The corresponding annualized event rates were 0.45% per year for MPI and 0.54% per year for echocardiography. In subgroup analyses, annualized event rates were <1% for each MPI isotope, and were similar for women and men. For secondary events, MPI and echocardiography had annualized event rates of 1.25% and 0.95%, respectively.

CONCLUSIONS

Both exercise MPI and exercise echocardiography have high NPVs for primary and secondary cardiac events. The prognostic utility of both modalities is similar for both men and women.

Stress-induced abnormalities in myocardial perfusion imaging that are not related to perfusion but are of diagnostic and prognostic importance

INTRODUCTION

Certain stress-induced ancillary findings on myocardial perfusion scintigraphy increase the likelihood that the patient has coronary artery disease (CAD); furthermore, among CAD patients, they indicate more severe and extensive disease, placing these patients at higher risk for future cardiac events. Indeed, in studies with no obvious perfusion defect yet with serious CAD--for example, balanced ischemia--it can be these high-risk findings that necessitate invasive intervention.

DISCUSSION

Besides reversible perfusion defects, such findings include increased pulmonary radiotracer uptake, transient cavity dilatation, increased end-diastolic or end-systolic volume, decreased post-stress ejection fraction, and increased right ventricular tracer uptake on stress images. The pathophysiology underlying these findings is clearly different as they do not always occur together, and each independently predicts more severe and extensive CAD. In the current review, these findings are defined and their significance in diagnosing patients with suspected or known CAD is discussed.

What is the Prognostic Value of Myocardial Perfusion Imaging Using Rubidium-82 Positron Emission Tomography?

OBJECTIVES

The objective was to determine the prognostic value of rubidium-82 (82Rb) positron emission tomography (PET) myocardial perfusion imaging (MPI).

BACKGROUND

82Rb PET MPI accurately diagnoses coronary artery disease (CAD). However, there are limited data evaluating its prognostic value.

METHODS

Follow-up (3.1 +/- 0.9 years) was obtained in 367 patients who underwent dipyridamole 82Rb PET MPI. Patients were divided into groups based on their summed stress score (SSS): group I, normal (<4); group II, mild (4 to 7); and group III, moderate (8 to 11) to severe (> or =12).

RESULTS

There were significant differences among patients in the 3 SSS groups for hard events (cardiac death and myocardial infarction [MI]) (p < 0.001) and total cardiac events (hard events, revascularization and hospitalization) (p < 0.001). The annual hard events rates were 0.4%, 2.3%, and 7.0% in the normal, mild, and moderate-severe groups, respectively. In adjusted survival models, 82Rb PET SSS was the strongest predictor of total cardiac events and a significant predictor of hard events. Among patients referred for PET after 99mTc single-photon emission computed tomography, the annual total event rate was higher with abnormal versus normal SSS on PET (15.2% vs. 1.3%, p < 0.001). In patients with obesity, the annual total event rate was 11.1% with an abnormal scan and 1.5% with a normal scan (p < 0.001).

CONCLUSIONS

This study shows that 82Rb PET MPI has significant prognostic value for predicting cardiac events, including death and MI. It also seems to have prognostic value in patients whose diagnosis remains uncertain after single-photon emission computed tomography MPI and in obese patients. The prognostic value of PET MPI may improve the management of cardiac patients.

Combined assessment of left ventricular perfusion and function by gated single-photon emission computed tomography for the risk stratification of high-risk hypertensive patients

OBJECTIVE

This study was aimed at verifying whether combined information on left ventricular perfusion and function by electrocardiogram-gated single-photon emission computed tomography (SPECT) retains its known prognostic value in patients with systemic hypertension.

METHODS

A total of 415 hypertensive patients underwent rest and stress (exercise in 278 and dipyridamole in 137) gated 99mTc-sestamibi SPECT and prospective follow-up for the composite endpoint of death and acute coronary syndrome. Patients undergoing revascularization were censored. The individual effect of clinical and stress imaging data on outcome was evaluated by Cox regression analysis. Model validation was performed using bootstrap methods adjusted by the degree of optimism in estimates. Survival analysis was performed using the product-limit Kaplan-Meier method.

RESULTS

During a median follow-up of 24 months, 12 cardiac deaths and 32 acute coronary syndromes occurred. After adjusting for the most significant covariates, age [hazard ratio (HR) 1.62, 95% confidence interval (CI) 1.02-2.57], diabetes (HR 7.51, 95% CI 1.61-35.2), summed stress score (HR 2.06, 95% CI 1.07-4), and peak end-systolic volume (HR 3.62, 95% CI 1.35-9.69) were multivariable predictors of outcome. The normal perfusion pattern was associated with a low event rate independently of peak end-systolic volume. Conversely, in the case of moderate to severe perfusion abnormalities, a peak end-systolic volume greater than 74 ml was able to identify an increased risk of adverse outcome. Moreover, peak end-systolic volume was significantly higher among patients who died of a cardiac cause compared with those with different outcomes.

CONCLUSION

A combined assessment of left ventricular perfusion and function by gated SPECT significantly improves risk stratification in hypertensive patients.

A model that accounts for the interdependence of extent and severity in the automatic evaluation of myocardial defects

BACKGROUND

The extent and severity are two important parameters when describing a regional defect in myocardial single-photon emission computed tomography (SPECT) perfusion imaging. Intuitively, these two parameters should be independent of each other, but we have shown in a previous study that there is an interdependence. This interdependence has been investigated in two commercially available analysis programs (AutoQUANT and 4D-MSPECT) using Monte Carlo-simulated SPECT data.

METHODS

An anthropomorphic digital computer phantom and a Monte Carlo program were used to generate SPECT data. Several defects of different volumes and lesion activity uptake reductions were simulated and evaluated. Comparison of the measures of extent and severity with their corresponding known values led to the development of a correction model based on least-squares parameter estimation. This model was then applied to a test group consisting of 10 different computer-simulated patients.

RESULTS

Our results showed that the interdependence was reduced significantly for most of our test cases after applying the correction method. The application of the correction model to the test group demonstrated that the model was robust with respect to different patient geometries. A further test with projections that simulated a perfect SPECT system revealed that the interdependence between the extent and severity was not caused by the limited spatial resolution of the SPECT system, but rather the inherent design of the algorithms of the analysis programs.

CONCLUSIONS

A model has been developed to take into account the interdependence of the extent and severity.

Third Annual Mario S. Verani, MD, Memorial Lecture: The future of clinical nuclear cardiology

It is a great honor and privilege to present the Third Annual Mario S. Verani, MD, Memorial Lecture. Mario Verani (1943-2001) will be remembered foremost for his major contributions to the field of nuclear cardiology (Figure 1). For instance, he was one of the first investigators to recognize that fixed thallium defects were often not just scar but could be reversed by coronary revascularization. This led to an extensive revision of accepted traditional concepts on the meaning of image patterns. Mario's work on risk stratification by myocardial perfusion and function imaging after acute myocardial infarction was equally pioneering. He also laid out the basic principles for the safe use of adenosine for pharmacologic stress testing. Adenosine is now the preferred procedure all over the world in millions of patients. Dr Verani was a founding member and past president (1996-1997) of the American Society of Nuclear Cardiology (ASNC). The day before he died, he received the ASNC Distinguished Service Award. Personally, I will remember Mario as a very dear friend. We spent many hours together at meetings and gatherings all over the world. I still miss his outgoing personality, his warmth, his humor, and his enthusiasm. Above all, I enjoyed his comfortable friendship. That this friendship extended itself naturally to our wives, Regina and Marjan, made it all the more special. One of the best times we had was during a cardiology meeting in Recife, in the country of his birth, Brazil. I was greatly amused and, at the same time, impressed by the admiration and respect bestowed on him by his fellow Brazilians. One evening, we were going some place in the street on foot. We could not walk down the street without Mario being stopped by one or another Brazilian cardiologist who wanted to speak and consult with him. He was clearly greatly admired and appreciated in his country. I jokingly called him "King of Recife," and the king was holding audience. We arrived rather late where we were going... . I will always cherish the memories of our times together. I am grateful that I could visit Mario at his sickbed on the day before he passed away. He was so fragile and, at the same time, so courageous. I felt sad that there was so much that we could have discussed that we did not. Life seems sometimes full of missed opportunities... .

Potential Indications for Coronary Angiography by Computed Tomography

Recent advances in computed tomography technology have made possible angiographic images of relatively small, moving vascular structures such as the coronary arteries. Computed tomographic coronary angiography is an exciting modality which has several obvious advantages over invasive catheterization, such as its relatively noninvasive nature and rapid speed of acquisition. However, significant drawbacks still exist, including limitations of spatial and temporal resolution and radiation exposure. Computed tomographic coronary angiography appears best suited as a diagnostic modality for the patient population with a low-to-moderate pretest probability of coronary artery disease, and for specific indications such as the imaging of coronary anomalies and bypass grafts and before biventricular pacemaker placement and atrial fibrillation ablation.

Prognostic value of combined perfusion and function by stress technetium-99m sestamibi gated SPECT myocardial perfusion imaging in patients with suspected or known coronary artery disease

The incremental prognostic value of combined regional wall motion and perfusion over perfusion alone by gated single-photon emission computed tomographic myocardial perfusion scintigraphy has not been evaluated. Of the 402 consecutive patients who underwent stress single-photon emission computed tomographic myocardial perfusion scintigraphy for suspected myocardial ischemia, we identified 333 patients (217 men, mean age 63 +/- 10 years; exercise in 249 and dipyridamole adminstered to 84). Visual scoring of perfusion images and regional wall motion used 20 segments and a scale of 0 to 4. Resting and poststress left ventricular ejection fraction was automatically generated. On follow-up (median 13 months), 30 hard cardiac events (17 cardiac deaths, 13 nonfatal acute myocardial infarctions) and 66 total cardiac events (including hard events, 26 with unstable angina, and 10 who underwent late revascularization) occurred. After adjustment for prescan information, the best independent predictors of hard events were summed stress score for wall motion (Wald's chi-square 8.3, p <0.004) and several vascular territories with ischemia by perfusion/function (Wald's chi-square 6.2, p <0.01). The strongest predictors of all cardiac events were the number of ischemias (Wald's chi-square 32.1, p <0.0001) and the number of ischemic vascular territories by perfusion (Wald's chi-square 13.1, p <0.0001). Addition of function data to the combined model of perfusion data yielded an incremental value of 26% for predicting hard events but not for all events. In conclusion, the assessment of combined perfusion/function provides incremental prognostic information for further hard events with perfusion data alone; perfusion data best predict all cardiac events.

The use of nuclear cardiology in clinical decision making

Extensive data exist to support the role of myocardial perfusion single-photon emission computed tomography (MPS) in risk stratification. Normal MPS studies usually are associated with very low risk, and patient risk increase significantly as a function of MPS results. Ventricular function measurements from gated single-photon emission computed tomography further augment risk stratification, particularly with respect to identifying patients at risk of cardiac death. Ancillary findings are prognostically important, particularly in the setting of normal or near-normal MPS results. Recent data suggest that MPS results can identify which patients will benefit from revascularization versus medical therapy and have expanded the understanding of how stress MPS is helpful in the identification of risk, enhanced the means of identifying risk, and improved its use as a means to identify optimal posttest treatment.

Use of myocardial perfusion imaging to predict the effectiveness of coronary revascularisation in patients with stable angina pectoris

PURPOSE

Coronary revascularisation is the treatment of choice in patients with stable angina who have significant stenoses. From a pathophysiological point of view, however, mitigation of angina is to be expected only in the presence of reversible ischaemia. Therefore it was the aim of this study to examine the effect of revascularisation on stable angina in relation to the myocardial perfusion imaging (MPI) pattern prior to intervention.

METHODS

Three hundred and eighty-four patients (58.0+/-8.8 years) referred for angiography underwent MPI. Prior to MPI and at 2-year follow-up, patients were classified as having typical angina, atypical angina, non-cardiac chest pain or no pain, and the severity of chest pain was graded according to the Canadian Cardiovascular Society (CCS) criteria. The patients themselves estimated their pain on a visual analogue scale. Management was based on symptoms and angiographic findings, since the results of MPI were not communicated.

RESULTS

Among the 240 patients who were not revascularised, 79% had typical or atypical angina at study entrance versus 40% at follow-up. In comparison, 93% of the 144 revascularised patients had typical or atypical angina before intervention versus only 36% at follow-up. This additional advantage of invasive therapy was present only in patients with reversible defects; revascularisation had no additional effect in patients with normal perfusion or irreversible defects. Similarly, additional, significant reductions in CCS class and visual analogue score were observed exclusively in patients with reversible defects.

CONCLUSION

In patients referred for coronary angiography owing to known or suspected stable angina, revascularisation was significantly more effective than medical treatment exclusively in patients with reversible ischaemia.

Quantitative single-photon emission computed tomography imaging

Over the past decade, quantitation of cardiac single-photon emission computed tomography (SPECT) data, once limited to perfusion assessment, has been extended to global and regional function assessment for both the left and the right ventricle, as well as to measurement of additional cardiac parameters of diagnostic and prognostic interest. A number of commercially available quantitative algorithms exist, based on different mathematic operators and with varying degrees of automation, that are capable of providing accurate and reproducible results. This article describes the many quantitative cardiac SPECT measurements available today, defining them in terms of validation, practical use, and limitations.

Can the reversible regional wall motion abnormalities on stress gated Tc-99m sestamibi SPECT predict a future cardiac event?

BACKGROUND

Myocardial stunning has recently been demonstrated by use of stress gated technetium 99m sestamibi single photon emission computed tomography (SPECT) myocardial perfusion scintigraphy. However, its prognostic value is less well determined. The aim of this study was to investigate the prognostic value of reversible regional wall motion abnormalities (RWMAs).

METHODS AND RESULTS

We studied 303 consecutive subjects with known or suspected coronary artery disease who underwent 2-day stress-rest gated Tc-99m sestamibi SPECT and were followed up for 19 +/- 16 months. Clinical and test-derived variables were evaluated to predict cardiac death, nonfatal myocardial infarction (MI), unstable angina, and early or late coronary revascularization. Reversible RWMAs were identified in 102 patients. On Cox analysis, the presence, site, degree, and extent of reversible RWMAs did not identify an adverse outcome, except in patients without prior MI. After adjustment for prescan data, the strongest predictors of hard events and all cardiac events were poststress RWMAs and the amount of ischemia. The addition of poststress RWMAs to the combined model of prescan and perfusion data yielded incremental prognostic value.

CONCLUSION

Poststress RWMAs and ischemia by perfusion were the most powerful predictive parameters of cardiac events. However, myocardial stunning should always be considered, particularly in patients without prior MI and in the referral of patients for early revascularization.

Should simultaneous exercise become the standard for adenosine myocardial perfusion imaging?

Concomitant low-level treadmill exercise with adenosine pharmacologic stress (AdenoEx) during radionuclide myocardial perfusion imaging has become commonly used in recent years, particularly in large-volume laboratories. A number of studies have demonstrated a beneficial impact of AdenoEx protocols. These benefits include decreased side effects, improved safety and patient tolerance, improved target-to-background ratios because of less subdiaphragmatic activity, and improved sensitivity and defect reversibility. In light of these benefits, recent reviews and guidelines call for the addition of low-level exercise to adenosine stress whenever possible.