Risk stratification in patients with remote prior myocardial infarction using rest-stress myocardial perfusion SPECT: prognostic value and impact on referral to early catheterization

Improved Performance of PET Myocardial Perfusion Imaging Compared to SPECT in the Evaluation of Suspected CAD

PURPOSE OF REVIEW

Myocardial perfusion imaging (MPI) with single photon emission computed tomography (SPECT) has played a central role in the non-invasive evaluation of patients with obstructive coronary artery disease (CAD) for decades. In this review, we discuss the key differences and advantages of positron emission tomography (PET) MPI over SPECT MPI as it relates to the diagnosis, prognosis, as well as clinical decision-making in patients with suspected CAD.

RECENT FINDINGS

Stress-induced perfusion abnormalities on SPECT help estimate presence, extent, and location of ischemia and flow-limiting obstructive CAD, help with risk stratification, and serve as a gatekeeper to identify patients who will benefit from downstream revascularization versus medical management. Some of the major limitations of SPECT include soft-tissue attenuation artifacts, underestimation of ischemia due to reliance on relative perfusion assessment, and longer protocols with higher radiation dose when performed with traditional equipment. PET MPI addresses most of these limitations and offers better quality images, higher diagnostic accuracy along with shorter protocols and lower radiation dose to the patient. A special advantage of PET scanning lies in the ability to quantify absolute myocardial blood flow and assess true extent of epicardial involvement along with identifying non-obstructive phenotypes of CAD such as diffuse atherosclerosis and microvascular dysfunction. In addition, stress acquisition at/near peak stress with PET allows us to measure left ventricular ejection fraction reserve and myocardial blood flow reserve, which help with identifying patients at a higher risk of future cardiac events and optimally select candidates for revascularization. The several technical advantages of PET MPI position as a superior method to diagnose obstructive and non-obstructive phenotypes of ischemic heart disease affecting the entirety of the coronary circulation offer incremental value for risk stratification and guide post-test management strategy for patients with suspected CAD.

Cardiovascular imaging following perioperative myocardial infarction/injury

Patients developing perioperative myocardial infarction/injury (PMI) have a high mortality. PMI work-up and therapy remain poorly defined. This prospective multicenter study included high-risk patients undergoing major non-cardiac surgery within a systematic PMI screening and clinical response program. The frequency of cardiovascular imaging during PMI work-up and its yield for possible type 1 myocardial infarction (T1MI) was assessed. Automated PMI detection triggered evaluation by the treating physician/cardiologist, who determined selection/timing of cardiovascular imaging. T1M1 was considered with the presence of a new wall motion abnormality within 30 days in transthoracic echocardiography (TTE), a new scar or ischemia within 90 days in myocardial perfusion imaging (MPI), and Ambrose-Type II or complex lesions within 7 days of PMI in coronary angiography (CA). In patients with PMI, 21% (268/1269) underwent at least one cardiac imaging modality. TTE was used in 13% (163/1269), MPI in 3% (37/1269), and CA in 5% (68/1269). Cardiology consultation was associated with higher use of cardiovascular imaging (27% versus 13%). Signs indicative of T1MI were found in 8% of TTE, 46% of MPI, and 63% of CA. Most patients with PMI did not undergo any cardiovascular imaging within their PMI work-up. If performed, MPI and CA showed high yield for signs indicative of T1MI.Trial registration: https://clinicaltrials.gov/ct2/show/NCT02573532 .

Quality of life as predictor for the development of cardiac ischemia in high-risk asymptomatic diabetic patients

BACKGROUND

Ischemia induced by psychological stress and depression is a common phenomenon in stable coronary artery disease (CAD). We evaluated the quality of life (QoL) of diabetic patients screened for CAD and assessed the prognostic value of mental and physical QoL scores to predict the development of new cardiac ischemia.

METHODS

Prospective multicentre outcome study. The study comprised 400 asymptomatic diabetic patients without history or symptoms of CAD. They underwent myocardial perfusion single-photon emission computed tomography (MPS) and assessment of QoL by two questionnaires: Hospital Depression and Anxiety Scale (HADS-D and HADS-A) and Medical Outcomes Study Short Form 36 (SF-36) at baseline and after 2 years. Patients with normal MPS received usual care; those with abnormal MPS received medical or combined invasive and medical management.

RESULTS

Only mental QoL scores but not physical QoL scores or traditional cardiovascular risk factors were predictive of new ischemia (n = 11/306) during follow-up. The prognostic value for new ischemia as quantified by the area under the receiver operating characteristics curve (AUC) amounted to 0.784 (95% confidence interval (CI) 0.654-0.914, P = 0.002) for HADS-D and to 0.737 (95% CI 0.580-0.893, P = 0.011) for HADS-A. This finding was confirmed by SF-36 mental sum score (AUC 0.688, 95% CI 0.539-0.836, P = 0.036), but not SF-36 physical sum score. QoL scores did not change after 2 years in patients with ischemia at baseline.

CONCLUSIONS

QoL scores assessing mental health, particularly depression and anxiety, predicted the development of new cardiac ischemia in asymptomatic diabetic patients. The study is limited by a small number of events (new ischemia) and so the results should be considered hypothesis generating rather than conclusive.

Role of risk stratification by SPECT, PET, and hybrid imaging in guiding management of stable patients with ischaemic heart disease: expert panel of the EANM cardiovascular committee and EACVI

Risk stratification has become increasingly important in the management of patients with suspected or known ischaemic heart disease (IHD). Recent guidelines recommend that these patients have their care driven by risk assessment. The purpose of this position statement is to summarize current evidence on the value of cardiac single-photon emission computed tomography, positron emission tomography, and hybrid imaging in risk stratifying asymptomatic or symptomatic patients with suspected IHD, patients with stable disease, patients after coronary revascularization, heart failure patients, and specific patient population. In addition, this position statement evaluates the impact of imaging results on clinical decision-making and thereby its role in patient management. The document represents the opinion of the European Association of Nuclear Medicine (EANM) Cardiovascular Committee and of the European Association of Cardiovascular Imaging (EACVI) and intends to stimulate future research in this field.

Progression to overt or silent CAD in asymptomatic patients with diabetes mellitus at high coronary risk: main findings of the prospective multicenter BARDOT trial with a pilot randomized treatment substudy

OBJECTIVES

The purpose of this study was to evaluate prevalence, progression, treatment, and outcome of silent coronary artery disease (CAD) in asymptomatic patients with diabetes (DM) at high coronary risk.

BACKGROUND

Despite the close association of diabetes and CAD, general CAD screening in asymptomatic patients with DM is discouraged even though outcome data in patients at high coronary risk are lacking.

METHODS

Prospective multicenter outcome study-with a pilot randomized treatment substudy. The study comprised 400 asymptomatic patients with DM (type 2) without history or symptoms of CAD at high CAD risk. They underwent clinical evaluation and myocardial perfusion single-photon emission computed tomography (MPS) at baseline and after 2 years. Patients with normal MPS received usual care; those with abnormal MPS received medical or combined invasive and medical management.

RESULTS

An abnormal MPS was found in 87 of 400 patients (22%). In patients with normal MPS, MACE occurred in 2.9% and ischemia or new scar in 3.2%. Patients with abnormal MPS had more MACE (9.8%; hazard ratio: 3.44; 95% confidence interval [CI]: 1.32 to 8.95; p = 0.011) and ischemia or new scar (34.2%; odds ratio: 15.91; 95% CI: 7.24 to 38.03; p < 0.001) despite therapy, resulting in "overt or silent CAD progression" of 35.6% versus 4.6% (odds ratio: 11.53; 95% CI: 5.63 to 24.70; p < 0.001). Patients with abnormal MPS randomized to medical versus invasive-medical strategies had similar event rates (p = 0.215), but more ischemic or new scar findings (54.3% vs. 15.8%; p < 0.001).

CONCLUSIONS

High-risk asymptomatic patients with DM and normal MPS (78%) have a low rate of first manifestations of CAD. Patients with abnormal MPS at baseline (22%) have a 7-fold higher rate of progression to "overt or silent CAD," despite therapy. Randomized patients' outcomes suggest that a combined invasive and medical strategy for silent CAD may reduce scintigraphic but not symptomatic CAD progression versus medical therapy alone. (Trial of Invasive versus Medical therapy of Early coronary artery disease in Diabetes Mellitus ISRCTN87953632).

Assessing the prognostic implications of myocardial perfusion studies: identification of patients at risk vs patients who may benefit from intervention?

Stress myocardial perfusion imaging (MPI) has a well-established role in improving risk stratification. Recent analyses, compared with older data, suggest that the yield of stress MPI has decreased. In part, this trend relates to testing patients with heterogeneous, but improved, risk factor modification. In this setting, positron emission tomography with myocardial flow reserve enhances risk stratification as it reflects the end result of atherosclerosis. Recent studies have also emphasized the clinical impact of incremental risk stratification by assessing net reclassification improvement (NRI). Previous retrospective studies have favored an ischemic threshold to select patients that benefit from revascularization, but this finding has not been corroborated in randomized trials. However, no large randomized trial has directly tested a strategy of revascularization for patients with at least a moderate amount of ischemia at risk. Unfortunately, even when faced with a significantly abnormal MPI result, subsequent action is too often absent.

Prevalence, extent, and independent predictors of silent myocardial infarction

BACKGROUND

The phenomenon of silent myocardial infarction is poorly understood.

METHODS

We aimed to evaluate the prevalence, extent, and independent predictors of silent myocardial infarction in 2 large independent cohorts of consecutive patients without a history of myocardial infarction referred for rest/stress myocardial perfusion single photon emission computed tomography. There were 1621 patients enrolled in the derivation cohort and 338 patients in the validation cohort. Silent myocardial infarction was diagnosed in patients with a myocardial scar ≥5% of the left ventricle.

RESULTS

In the derivation cohort, the prevalence of silent myocardial infarction was 23.3% (n = 377). The median infarct size was 10% (interquartile range [IQR] 5%-15%) of the left ventricle. The prevalence of silent myocardial infarction was 28.5% in diabetics and 21.5% in nondiabetics (P = .004). Diabetes mellitus was an independent predictor for the presence of silent myocardial infarction (odds ratio 1.5; 95% confidence interval, 1.1-1.9; P = .004). These findings were confirmed in the independent validation cohort. In the validation cohort, the prevalence of silent myocardial infarction was 26.3% (n = 89), while the prevalence was higher in diabetics (35.8%) than in nondiabetics (24%; P = .049). The median infarct size was 11.8% (IQR 5.9%-17.6%) of the left ventricle. Again, in logistic regression analysis, diabetes mellitus was a significant predictor of the presence of silent myocardial infarction.

CONCLUSION

Silent myocardial infarctions are more common than previously thought. One of 4 patients with suspected coronary artery disease had experienced a silent myocardial infarction; the extent in average is 10% of the left ventricle, and it is more common in diabetics.

Prediction of future cardiac events using myocardial perfusion SPECT: a middle-term follow-up study

BACKGROUND

Myocardial perfusion imaging (MPI) provides highly valuable information for risk stratification and determination of optimal clinical management. The goal of the present study was to assess the prognostic value of myocardial perfusion SPECT for the prediction of future cardiac events in Asian population.

METHODS

Five hundred and ten consecutive patients, who had undergone myocardial perfusion SPECT between 2005 and 2006, were prospectively followed-up. Patients' data were collected from recorded files. Follow-ups were performed by scripted telephone interviews by a physician blinded to the patients' MPI results and also from the hospital records. The total completed follow-ups consisted of 482 patients (follow-up rate, 94.5%).

RESULTS

Over the mean follow-up period of 434 ± 62 days, 14 out of 482 patients (2.9%) died from cardiac events. Also in 61 patients (12.7%), the clinical condition led to a cardiac intervention (Percutaneous coronary intervention or coronary artery bypass grafting). Those patients without cardiac events on follow-up (including cardiac death or myocardial infarction) were younger and with less severity of MPI abnormalities. Severe MPI abnormalities (Summed Stress Score > 13) were found in 42.9% of those with cardiac death, while in 17.2% of those with myocardial infarction. The rate of cardiac death had a direct relationship with the severity of scan abnormalities, however, the same association was not found between the severity of MPI abnormality and the rate of myocardial infarction.

CONCLUSION

MPI is a valuable tool for risk stratification and prediction of future fatal cardiac events in Asian population. The risk of cardiac death as a mid-term outcome of coronary artery disease increases significantly with severity of MPI abnormalities.

Combined assessment of myocardial perfusion and function by ECG-gated myocardial perfusion single-photon emission computed tomography for the prediction of future cardiac events in patients with type 2 diabetes mellitus

BACKGROUND

The mid-term prognostic significance of ECG-gated single-photon emission computed tomography (SPECT) remains unclear in Japanese patients with type 2 diabetes mellitus (DM). In the present study rates of future cardiac events (nonfatal acute myocardial infarction (AMI), cardiac death (CD) and severe heart failure (HF) requiring hospitalization) were compared in patients with and without DM.

METHODS AND RESULTS

1,810 patients (563 DM and 1,247 non-DM) we followed for a mean of 26.3±15.5 months. Summed stress score (SSS), summed difference score (SDS), poststress ejection fraction (EF) and resting end-diastolic volume (EDV) were calculated. In total, 20 cases of AMI (9 in DM (1.59%) and 11 in non-DM (0.88%)), 20 of CD (7 in DM patients (1.24%) and 13 in non-DM (1.04%)) and 54 of severe HF (31 in DM (5.5%) and 23 in non-DM (1.84%)) occurred. Univariate Cox analysis showed that, in DM patients, predictors of total cardiac events were poststress EF (Wald 60.4; P<0.001), resting EDV (Wald 53.8; P<0.001), SSS (Wald 39.6; P<0.001), SDS (Wald 26.1; P<0.001), history of prior MI (Wald 4.32; P<0.05) and hemoglobin A(1c) value (Wald 4.30; P<0.05). Multivariate Cox analysis showed that poststress EF (Wald 9.85; P<0.01) and SDS (Wald 6.19; P<0.01) were independent predictors of total cardiac events.

CONCLUSIONS

Combined assessment of perfusion and function by ECG-gated SPECT may predict future cardiac events in type 2 DM patients.

The present state of coronary computed tomography angiography a process in evolution

In the past 5 years since the introduction of 64-detector row cardiac computed tomography angiography (CCTA), there has been an exponential growth in the quantity of scientific evidence to support the feasibility of its use in the clinical evaluation of individuals with suspected coronary artery disease (CAD). Since then, there has been considerable debate as to where CCTA precisely fits in the algorithm of evaluation of individuals with suspected CAD. Proponents of CCTA contend that the quality and scope of the available evidence to date support the replacement of conventional methods of CAD evaluation by CCTA, whereas critics assert that clinical use of CCTA is not yet adequately proven and should be restricted, if used at all. Coincident with the scientific debate underlying the clinical utility of CCTA, there has developed a perception by many that the rate of growth in cardiac imaging is disproportionately high and unsustainable. In this respect, all noninvasive imaging modalities and, in particular, more newly introduced ones, have undergone a higher level of scrutiny for demonstration of clinical and economic effectiveness. We herein describe the latest available published evidence supporting the potential clinical and cost efficiency of CCTA, drawing attention not only to the significance but also the limitations of such studies. These points may trigger discussion as to what future studies will be both necessary and feasible for determining the exact role of CCTA in the workup of patients with suspected CAD.

The additive prognostic value of perfusion and functional data assessed by quantitative gated SPECT in women

BACKGROUND

The aim of this study was to assess the prognostic value of technetium-99m tetrofosmin gated SPECT imaging in women using quantitative gated single photon emission computed tomography (SPECT) imaging.

METHODS

We followed 453 consecutive female patients. Average follow-up was 1.33 years (max. 2.55). Hard endpoints were cardiac death, acute myocardial infarction, or documented ventricular fibrillation. Event-free survival curves were obtained. Optimal cutoff values for left ventricular (LV) volumes, LV ejection fraction (LVEF), and perfusion data to predict outcome were determined by ROC curve analysis.

RESULTS

A total of 236 patients had an abnormal study, of whom 27 patients experienced hard events (16 deaths) and 47 patients soft events. For hard events summed stress score (SSS) and LVEF, and for any cardiac event SSS showed independent incremental prognostic value. The survival curves were maximally separated when using cutoff values for SSS of > or = 22 and LVEF < 52% (P < 0.001, HR 4.61 and P < 0.001 HR 5.24 for SSS and LVEF resp.), and SSS > or = 14 (P < 0.001 HR 3.76) for any cardiac event.

CONCLUSION

In women, perfusion and functional parameters derived from quantitative gated technetium-99m tetrofosmin SPECT imaging can adequately be used for cardiac risk assessment. Using quantitative gated SPECT, female patients with an LVEF < 52% or an SSS > or = 22 are at increased risk for subsequent hard events. Furthermore, patients with an SSS > or = 14 are at increased risk for any cardiac events.

Incremental prognostic value of cardiac function assessed by ECG-gated myocardial perfusion SPECT for the prediction of future acute coronary syndrome

BACKGROUND

The prognostic value of ECG-gated rest 201Tl/stress 99mTc-tetrofosmin myocardial perfusion single-photon emission computed tomography for the prediction of acute coronary syndrome (ACS: myocardial infarction (MI) and unstable angina (UA)) and the implications of ejection fraction (EF) has not yet been defined in Japanese.

METHODS AND RESULTS

The 1,895 patients were followed up for the occurrence ACS. The mean follow-up interval was 26.9+/-15.5 months. The 142 patients with revascularization within 60 days were censored. Summed stress score (SSS) and summed difference score (SDS) were calculated. The 19 MI and 29 UA occurred (1.1% and 1.6%, respectively). Univariate Cox analysis showed that hypertension (Wald 5.09, p<0.05), poststress EF (Wald 10.9, p<0.01), SSS (Wald 12.4, p<0.001) and SDS (Wald 18.7, p<0.001) were significant predictors of ACS. Multivariate Cox analysis showed that hypertension (Wald 4.27, p<0.05) and SDS (Wald 8.59, p<0.01) were independent predictors. When multiple clinical risk factors (number of coronary risk factors > or =2), significant ischemia (SDS > or =4) and low EF (EF <45%) were applied to multivariate Cox analysis, the combination of significant ischemia and low EF showed the highest predictive value (Wald 11.9; p<0.001) for future ACS.

CONCLUSION

Poststress EF added incremental prognostic value for the prediction of ACS.

Chest Pain Units: Management of Special Populations

Chest pain units provide an important alternative to traditional hospital admission for patients who present to the emergency department with symptoms compatible with acute coronary syndrome and a normal or inconclusive initial evaluation. Although patient subgroups such as women, diabetics, those with established coronary artery disease,and those with symptoms related to stimulant use present unique challenges,management in a chest pain unit appears to be appropriate in these populations. Judicious application of accelerated diagnostic protocols and current testing methods can promote safe, accurate, and cost-effective risk stratification of special populations to identify patients who can be safely discharged and patients who require hospital admission for further evaluation.

Systematic review of the prognostic effectiveness of SPECT myocardial perfusion scintigraphy in patients with suspected or known coronary artery disease and following myocardial infarction

OBJECTIVES

In patients with suspected or known coronary artery disease (CAD), or following myocardial infarction (MI), assessing the degree of ischaemia is important from a prognostic and therapeutic point of view. Single photon emission computed tomography (SPECT) myocardial perfusion scintigraphy (MPS) is a non-invasive technique that allows the presence, location and extent of ischaemia to be determined. The aim of this systematic review was to assess the prognostic effectiveness of SPECT MPS.

METHODS

We sought prognostic studies involving SPECT, exercise tolerance testing (ETT) and/or coronary angiography (CA) in people with suspected or known CAD, or following MI. Outcomes included cardiac death, non-fatal MI and revascularization. We searched the following databases: MEDLINE, PREMEDLINE, EMBASE, BIOSIS, Science Citation Index, the Cochrane Library, the Health Management Information Consortium and the Health Technology Assessment Database.

RESULTS

Twenty-one observational studies enrolling 53,762 people reported the general prognostic value of SPECT MPS. In multivariate analysis, SPECT MPS variables yielded both independent and incremental value to combinations of clinical, ETT and angiographic variables in predicting cardiac death or non-fatal MI. Three comparative studies reported lower revascularization rates following a SPECT MPS-CA strategy (6-21%) compared with direct CA (16-44%). Four observational studies enrolling 2106 people reported the prognostic value of SPECT for patients following MI. In multivariate analysis including clinical history, ETT, SPECT MPS and angiographic variables, strategies involving SPECT MPS provided independent and incremental prognostic performance in predicting future cardiac events.

CONCLUSIONS

SPECT MPS provides important additional information to that from ETT and/or CA that helps to risk-stratify patients with suspected or known CAD or following MI, enabling them to be managed more appropriately. Increasing the use of strategies involving SPECT MPS may identify lower risk patients for whom invasive CA might be avoided.

Prognostic value of stress Tc-99m tetrofosmin SPECT in patients with previous myocardial infarction: impact of scintigraphic extent of coronary artery disease

BACKGROUND

Our objective was to assess the prognostic value of the scintigraphic extent of coronary artery disease on stress technetium 99m tetrofosmin single photon emission computed tomography in patients with previous myocardial infarction.

METHODS AND RESULTS

We studied 383 patients (280 men and 103 women; mean age, 60 +/- 11 years) more than 3 months after an acute myocardial infarction by exercise bicycle or dobutamine (up to 40 mug . kg -1 . min -1 ) stress Tc-99m tetrofosmin myocardial perfusion tomography. Stress images were acquired 1 hour after stress, and rest images were acquired 24 hours after stress testing. An abnormal study was defined as one demonstrating a reversible or fixed perfusion abnormality. Myocardial segments were assigned to corresponding coronary arteries as follows: the apex, anterior wall, and anterior septum were assigned to the left anterior descending coronary artery; the posterolateral wall was assigned to the left circumflex artery; and the basal posterior septum and inferior wall were assigned to the right coronary artery. During a mean follow-up of 4.3 +/- 2.1 years, 48 cardiac events occurred (36 cardiac deaths and 12 nonfatal myocardial infarctions). Myocardial perfusion was normal in 51 patients, abnormal in a single-vessel distribution in 170 patients, and abnormal in a multivessel distribution in 162 patients. The annual cardiac event rates in these groups were 0.4%, 2.6%, and 4%, respectively. In a multivariate analysis model, independent predictors of cardiac events were diabetes mellitus (odds ratio [OR], 2.3; 95% confidence interval [CI], 1.4-4.5), history of congestive heart failure (OR, 2.7; 95% CI, 1.4-4), age (OR, 1.05; 95% CI, 1.01-1.08), and scintigraphic extent of coronary artery disease (OR, 4.2; 95% CI, 1.8-9.1).

CONCLUSION

Stress Tc-99m tetrofosmin myocardial perfusion imaging provides independent prognostic information for the risk stratification of patients with previous myocardial infarction. The event rate is directly related to the scintigraphic extent of coronary artery disease. Patients with normal perfusion have an excellent event-free survival rate.

Differential prognostic significance of peri-infarction versus remote myocardial ischemia on stress technetium-99m sestamibi tomography in patients with healed myocardial infarction

Peri-infarction and remote myocardial ischemia involve different myocardial substrates, but their differential clinical implications have not been previously studied. We assessed the differential prognostic significance of peri-infarction and remote ischemia during long-term follow-up in patients with healed myocardial infarction. We studied 345 patients (59 +/- 12 years old; 282 men) with previous myocardial infarction who demonstrated reversible perfusion abnormalities on exercise or dobutamine stress technetium-99m sestamibi tomography. Follow-up events for 5.5 +/- 2.6 years were 60 deaths (17%; 40 cardiac deaths) and 25 reinfarctions (7%). Reversible perfusion abnormalities were detected in the remote region in 129 patients (37%), the peri-infarction region in 142 patients (41%), and in both regions in 74 patients (21%). The annual rates of cardiac death in these groups were 1.2%, 2.8%, and 2.9%, respectively (p <0.01). The annual rates of reinfarction were 1%, 1.5%, and 0.9%, respectively (p = NS). In a multivariate analysis model, independent predictors of cardiac death were history of heart failure (risk ratio [RR] 2.8, 95% confidence interval [95% CI] 1.2 to 7), diabetes mellitus (RR 4.1, 95% CI 1.9 to 8.9), summed score at rest (RR 1.4, 95% CI 1.1 to 3.1), and peri-infarction ischemia (RR 2.6, 95% CI 1.1 to 6.1). Predictors of reinfarction were age (RR 1.03, 95% CI 1.01 to 1.07) and diabetes mellitus (RR 3.3, 95% CI 1.2 to 9.1). Peri-infarction ischemia assessed by stress technetium-99m sestamibi tomography is associated with a greater risk of cardiac death than is remote ischemia. The risk of reinfarction is not related to the location of ischemia.

Improved recognition of dysfunctioning myocardial segments by longitudinal strain rate versus velocity in patients with myocardial infarction

Doppler tissue imaging (DTI) can measure myocardial velocities but velocities alone cannot distinguish active from passive wall motion, whereas this is possible by strain rate (SR) imaging (SRI). We evaluated the accuracy of SRI for recognition of abnormal regional systolic function compared with DTI, B-mode echocardiography, and anatomic M-mode in 24 patients with myocardial infarction who underwent gated stress Tc 99m sestamibi scan. Sensitivity and specificity for recognition of infarct segments were 91% and 84% for visual SRI, 63% and 73% for visual DTI, 78% and 71% for B-mode echocardiography, and 87% and 77% for anatomic M-mode, respectively. Peak SRs correlated with wall-motion assessment by B-mode echocardiography better than peak velocities (P =.66 vs.10), with less overlap between groups. Therefore, SRI improves evaluation of regional wall motion compared with DTI and conventional ultrasound techniques in patients with myocardial infarction, mainly because it identifies segments that are moving passively but not shortening normally.

First annual Mario S. Verani, MD, Memorial lecture: clinical value of myocardial perfusion imaging in coronary artery disease

I am honored to give this lecture in memory of Dr Mario S. Verani, a friend and a respected colleague in the field of nuclear cardiology. Dr Verani made many immense contributions to the field of nuclear cardiology during his lifetime. He was a pioneer in the field of pharmacologic stress imaging and played a leading role in validating the utility of intravenous adenosine infusion for stress imaging in detecting significant coronary stenoses and assessing prognosis. He and his colleagues at Baylor reported that pharmacologic stress imaging could separate high- and low-risk patient subsets after acute myocardial infarction, particularly among patients who underwent thrombolytic therapy. He informed us that certain drugs that patients took could influence perfusion defect severity. This work led to a clinical study showing that ischemic defect size could be substantially reduced with medical therapy in patients who had recently had an acute infarction. An outcome of this observation was the launching of the INSPIRE (adenosINe technetium-99m Sestamibi single-photon emission computed tomography Post-InfaRction Evaluation) trial in which postinfarction patients are randomized to medical therapy or revascularization. Dr Verani was an able debater when assigned the position for advocating for stress radionuclide perfusion imaging against stress echocardiography. He engaged in these debates with substantial knowledge but always with a touch of humor. Dr Verani's courage was an inspiration to all of us during his illness. His legacy as a pioneer will endure as the field of nuclear cardiology continues to mature and expand.

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

OBJECTIVES

The purpose of this study was to evaluate the prognostic value of community-based myocardial perfusion imaging (MPI) and to assess the incremental value of individual components of (99m)Tc-sestamibi single photon emission computed tomography (SPECT).

BACKGROUND

Although the most rapid growth of MPI has been in community outpatient laboratories, its prognostic value has not been validated in this setting.

METHOD

We prospectively followed 1,612 consecutive patients undergoing stress (99m)Tc-sestamibi SPECT in an outpatient community laboratory who experienced 71 hard events over 24 +/- 7 months (0.2% lost to follow-up).

RESULTS

Patients whose scans were normal incurred an annualized event rate of 0.4%, compared with 2.3% for those with abnormal scans (p < 0.0001). Subset analysis demonstrated comparable risk stratification for women and men, diabetics, patients with normal resting ECGs, and those referred for pharmacologic and exercise stress. After adjusting for pre-test variables, multivariable Cox regression analysis found the most potent independent components of MPI to be, in order of importance, transient ischemic dilation, extent of reversibility, post-stress ejection fraction, extent and severity of the stress perfusion defect, and the overall test result (normal or abnormal). Each 1% decrement of ejection fraction predicted a 3% increase in risk (p = 0.0009). Post-MPI angiography and revascularization increased commensurate with the extent and severity of MPI result.

CONCLUSIONS

The prognostic value of perfusion imaging is portable and transferable to the outpatient community setting, with multiple components of MPI providing incremental prognostic information.

Prognostic significance of fixed perfusion abnormalities on stress technetium-99m sestamibi single-photon emission computed tomography in patients without known coronary artery disease

Fixed perfusion abnormalities in patients with known coronary artery disease (CAD) are associated with myocardial damage and adverse outcomes. However, the significance of these abnormalities in patients without known CAD is unclear. The aim of this study was to assess the prognostic significance of fixed versus reversible perfusion abnormalities in patients without known CAD. We studied 327 patients (58 +/- 11 years of age; 215 men) with no history of myocardial infarction or revascularization, who demonstrated myocardial perfusion abnormalities on stress (exercise or dobutamine) sestamibi tomographic imaging. Follow-up end points were all-cause mortality and hard cardiac events (cardiac death and nonfatal myocardial infarction). Myocardial perfusion abnormalities were reversible in 226 patients (69%) and fixed in 101 patients (31%). During a mean follow-up of 7 years, 72 patients (22%) died (cardiac death in 30) and 15 patients had nonfatal myocardial infarctions. The annual mortality rate was higher in patients with fixed abnormalities than in those with reversible abnormalities (4.4% vs 2.7%, p <0.01), whereas the annual hard cardiac event rate was not significantly different between the 2 groups (2.5% vs 2%). In a multivariate analysis model, the summed stress score was an independent predictor of hard cardiac events (risk ratio 1.7, 95% confidence interval 1.3 to 5.4). The presence of a fixed perfusion abnormality was independently associated with an increased risk of death after adjustment for clinical and stress test data and the summed stress score (risk ratio 2.5, 95% confidence interval 1.3 to 3.7). In patients with suspected, but no history of CAD, fixed perfusion abnormalities were associated with a higher risk of death compared with reversible perfusion abnormalities.

Long-term outcome of patients with silent versus symptomatic ischemia six months after percutaneous coronary intervention and stenting

OBJECTIVES

We sought to evaluate the incidence of silent ischemia versus symptomatic ischemia six months after percutaneous coronary intervention (PCI) and its impact on prognosis and to test the utility of myocardial perfusion single-photon emission computed tomography (SPECT), or MPS, for risk stratification in these patients.

BACKGROUND

Silent ischemia is frequent after PCI. However, little is known about silent ischemia and long-term outcome after PCI and stenting.

METHODS

In 356 consecutive patients with successful PCI and stenting and follow-up MPS after six months, long-term follow-up (4.1 +/- 0.3 years) was performed. The MPS images were interpreted by defining summed stress, rest, and difference scores (summed difference score [SDS] = extent of ischemia) and related to symptoms and outcome. Critical events included cardiac death, myocardial infarction, and target vessel revascularization.

RESULTS

Eighty-one patients (23%) had evidence of target vessel ischemia, which was silent in 62%. The only independent predictor of silent ischemia was SDS (odds ratio 0.64, p = 0.001). During follow-up, 67 critical events occurred. For patients with an SDS of 0, 1-4, and >4, the critical event rates were 17%, 29%, and 69%, respectively. Similarly, patients without ischemia, silent ischemia, and symptomatic ischemia had 17%, 32%, and 52% of critical events, respectively. Diabetes (relative risk 1.98, p = 0.03) and SDS (relative risk 1.2, p < 0.001) were independent predictors of critical events. The MPS image added incremental information for the prediction of critical events.

CONCLUSIONS

Six months after PCI and stenting, 23% of patients had target vessel ischemia, which was silent in 62%. Silent ischemia predicted a worse outcome than did no ischemia and tended to have a better outcome than symptomatic ischemia. This was closely related to the extent of ischemia. The SDS added incremental value to pre-scan findings with respect to diagnosis and prognosis, indicating the utility of MPS for risk stratification after PCI and stenting.