Prognostic value of stress myocardial perfusion imaging in octogenarian population

BACKGROUND: The prognostic value of myocardial perfusion imaging (MPI) in the very elderly population has not been addressed specifically. The aim of this study was to examine the characteristics of the octogenarian population referred for MPI and the prognostic value of the procedure in terms of patient gender. METHODS: The study sample consisted of 162 consecutive patients (61 women, 101 men) of mean age 83 +/- 3 years (range, 80-90) who underwent stress MPI. The duration of follow-up was 45+/-12 months. Outcome measures were cardiac-related death, and nonfatal myocardial infarction (MI). RESULTS: Thirty-one major cardiac events (19%) were recorded, including 26 cardiac deaths and 5 MI events, in 6 of the 61 women (10%) and 25 of the 101 men (25%) (p < 0.03). The univariate predictors of cardiac death or MI, except of known coronary artery disease (CAD), were MPI variables: left ventricular (LV) dilatation, increased lung uptake, abnormal scan, and the presence and extent of myocardial ischemia. However, the only predictors for major cardiac events were: LV dilatation (OR = 6.9, 95% CI 2.7-17.4, p < 0.0001) and ischemia by scan (OR = 2.75, 95% CI 1.09-6.96, p < 0.03). The Kaplan Meier curve demonstrated significant differences in survival between patients with or without LV dilatation and patients with or without ischemia. CONCLUSIONS: LV dilatation and myocardial ischemia were useful predictors of cardiac death and MI in octogenarian patients with CAD or with suspicion of CAD.     

Comparison of risk stratification with pharmacologic and exercise stress myocardial perfusion imaging: A meta-analysis

BACKGROUND: Although pharmacologic stress myocardial perfusion imaging (MPI) and exercise stress MPI have comparable diagnostic accuracy, their comparative value for risk stratification of patients with known or suspected coronary disease is not known. METHODS AND RESULTS: The data of 14,918 patients were combined from 24 studies evaluating prognosis in patients undergoing either pharmacologic stress or exercise stress MPI. Studies were included if a 2 x 2 table for hard cardiac events (cardiac death and myocardial infarction [MI]) could be constructed from the data available. Excluded were studies performed for post-MI, post-revascularization, or preoperative risk stratification. A weighted t test was used to compare the cardiac events, and a random effects model was used to calculate summary odds ratios. Summary odds ratios for hard cardiac events were similar for pharmacologic stress and exercise stress MPI. Summary receiver operating characteristic curves also showed no difference in discriminatory power between the stressors. The cardiac event rates were significantly higher with normal and abnormal test results with pharmacologic stress MPI than with exercise stress MPI (1.78% vs 0.65% [P < .001] for normal results and 9.98% vs 4.3% [P < .001] for abnormal results). Subgroup analysis revealed that both cardiac death and nonfatal MI were significantly higher with pharmacologic stress MPI. Patients undergoing pharmacologic stress MPI had a significantly higher prevalence of poor prognostic factors, and meta-regression revealed that exercise capacity was the single most important predictor of cardiac events. CONCLUSIONS: This meta-analysis shows that exercise stress MPI and pharmacologic stress MPI are comparable in their ability to risk-stratify patients. However, patients undergoing pharmacologic stress studies are at a higher risk for subsequent cardiac events. This is true even for those with normal perfusion imaging results.     

Sensitivity of acute rest myocardial perfusion imaging for identifying patients with myocardial infarction based on a troponin definition

BACKGROUND: Myocardial perfusion imaging (MPI) is often used to identify low-risk chest pain patients who have myocardial infarction (MI). A recent recommendation is that patients with increased troponin levels be diagnosed as having MI. The sensitivity and characteristics of patients who have elevated troponin levels who also underwent early MPI are unknown. METHODS AND RESULTS: Patients considered at low risk for MI underwent rest gated tomographic MPI and serial marker assessment as part of a standard chest pain evaluation protocol. Patients with cardiac troponin I (cTnI) elevations were analyzed further for this study. MPI results were considered positive if there was a perfusion defect in association with abnormal wall motion or thickening. Short-axis images were divided into 17 segments and graded on a 4-point scale (0, normal; 3, high-grade or absent perfusion), and a summed rest score was derived. Of the 319 patients who had MPI and cTnI elevations, 78 had negative MPI results (sensitivity, 75%). Patients with negative MPI results had lower peak creatine kinase (CK)-MB values (15 +/- 25 ng/mL vs 45 +/- 78 ng/mL, P <.0001) and higher ejection fractions (56% +/- 15% vs 47% +/- 13%, P <.0001) and were less likely to have significant disease (55% vs 72%, P =.04) than those with positive MPI results. Increasing summed rest score was associated with larger MIs as estimated by peak CK and CK-MB values. CONCLUSIONS: Patients with negative MPI results have smaller MIs and less extensive coronary disease. MPI and cTnI offer complementary data for assessing patients with possible MI.     

Prognostic significance of dipyridamole-induced ST depression in patients with normal 82Rb PET myocardial perfusion imaging.

Recent studies have shown that vasodilator-induced ischemic electrocardiographic (ECG) changes have incremental prognostic value over normal SPECT myocardial perfusion imaging (MPI) and identify patients at higher risk for cardiac events. The prognostic value of vasodilator-induced ischemic ECG changes in the setting of normal PET MPI has yet to be determined. We sought to determine the prognostic importance of dipyridamole-induced ischemic ECG changes in patients with normal 82Rb PET myocardial perfusion images. METHODS: Between 2000 and 2003, 2,029 consecutive patients undergoing dipyridamole stress 82Rb PET at the University of Ottawa Heart Institute were evaluated. Patients with normal PET MPI and interpretable ECGs were enrolled. Electrocardiograms were assessed for ST depression or elevation and patients were categorized into those with and without dipyridamole-induced ischemic ECG changes. Images were graded using the 17-segment model. Follow-up information was obtained by telephone interview, from hospital records, or from treating physicians. All cardiac events (cardiac death, nonfatal myocardial infarction [MI], percutaneous coronary intervention, coronary artery bypass grafting, or angiography) were verified with hospital records. RESULTS: Of the 629 enrolled patients with normal PET MPI, 72 patients had dipyridamole-induced ischemic ECG changes. There was no significant difference between the 2 groups in the combined endpoint (cardiac death, nonfatal MI, and revascularization) at follow-up (mean +/- SD, 27.1 +/- 13 mo). There were no cardiac deaths in either group. One (1.4%) patient with ischemic ECG changes had a nonfatal MI (0.6% annual event rate). Two (2.8%) patients with ischemic ECG changes required revascularization compared with 11 (2.0%) in the nonischemic ECG group. CONCLUSION: Normal 82Rb PET confers an excellent prognosis regardless of dipyridamole-induced ST depression.     

Prognosis in patients achieving ≥10 METS on exercise stress testing: Was SPECT imaging useful?

Background

The benefit of myocardial perfusion imaging (MPI) over exercise ECG stress testing alone is unclear in individuals attaining a workload of ≥10 METS. The purpose of this prospective study is to determine mortality and nonfatal cardiac events in patients at either intermediate pretest risk for CAD or patients with known CAD, achieving ≥10 METS regardless of peak exercise heart rate. The authors previously reported a low prevalence of significant ischemia in this patient cohort.

Methods

Baseline characteristics, ECG stress test findings, and perfusion and function results from quantitative gated ^99mTc-SPECT MPI were compared by achievement of a maximum age-predicted heart rate ≥85% in 509 consecutive patients who reached ≥10 METS. Events including all-cause and cardiac mortality, non-fatal myocardial infarction (MI), and late revascularization (>4 weeks after MPI) were prospectively collected.

Results

Of the 509 patients achieving ≥10 METS, follow-up for mortality was obtained in 463 (91%). Those lost to follow-up were older and had higher rates of tobacco use. The prevalences of CAD risk factors, prior known CAD, and MPI abnormalities were higher for the 68 patients failing to reach 85% of their target heart rate. The rate of ≥10% left-ventricular (LV) ischemia by MPI remained very low irrespective of attained heart rate (0.6% (3/463)). Six (1.2%) had an LVEF < 40%. Death occurred in 12 (2.6%) patients, one of which was classified as cardiac (0.1%/year). The other 11 deaths were related to cancer. Additionally, there were three nonfatal MIs (0.7 %) and one late revascularization (0.2%). Only one of these patients had any ischemia on MPI. No cardiac event patient had exercise ST depression or ≥5% LV ischemia.

Conclusions

Thus, patients at intermediate risk for CAD or known CAD achieving ≥10 METS have a very low prevalence of ≥10% LV ischemia and very low rates of cardiac mortality, nonfatal MI, and late revascularization, irrespective of heart rate achieved. Cardiac events did not correlate with abnormalities on the index MPI study. These results suggest that patients who attain ≥10 METS during exercise stress have an excellent prognosis over an intermediate term of follow-up, regardless of peak exercise heart rate achieved. The added value of MPI to standard exercise ECG testing in this population is questionable.     

Value of simultaneous functional assessment in association with acute rest perfusion imaging for predicting short- and long-term outcomes in emergency department patients with chest pain

Background. Rest tomographic myocardial perfusion imaging (MPI) has significant utility for clinical decision making in emergency department chest pain patients. The role of functional data, commonly acquired with perfusion, has not been systematically evaluated. Methods and Results. Low- to moderate-risk patients undergoing rest MPI for risk stratification were included. The patients’ MPI findings were classified as normal (normal perfusion or function), abnormal (perfusion defect with abnormal regional function), or discordant (perfusion defect with normal regional function). Ejection fraction was determined from the gated MPI studies. Events based on perfusion classifications and ejection fraction were evaluated. A total of 2,826 consecutive patients (abnormal MPI results in 40%, normal in 32%, and discordant in 27%) were studied. Outcomes were similar for those with normal MPI results versus those with discordant MPI results (myocardial infarction [MI] based on troponin I [TnI], 3.5% vs 4.0%; MI based on creatine kinase-MB, 1.5% vs 1.7%; revascularization, 5.2% vs 5.5%; and MI/revascularization based on TnI, 7.9% vs 8.1%) (P=not significant for all). Both groups had significantly fewer events (P<.001 for all) when compared with patients with abnormal MPI studies (MI based on TnI, 15%; MI based on creatine kinase-MB, 10%; revascularization, 17%; MI based on TnI or revascularization, 24%). The mortality rate was not different among the 3 groups. Multivariate analysis showed that mild/moderate and severe systolic dysfunction were independent predictors of 30-day and 1-year mortality rates (P=.001). Conclusions. The concurrent evaluation of perfusion and function (regional and global) with MPI provides significant risk/outcome predictive power.     

Prognostic significance of ischemic electrocardiographic changes during adenosine infusion in patients with normal myocardial perfusion imaging

BACKGROUND: The development of ST-segment depression during adenosine myocardial perfusion imaging (MPI) has been shown to be an independent predictor of subsequent cardiac events and worse outcome, particularly in association with ischemic defects. However, the prognostic significance of ST-segment depression with adenosine in patients with normal MPI is not known. METHODS AND RESULTS: We performed a retrospective analysis of 3231 patients undergoing adenosine MPI. Patients with baseline electrocardiographic (ECG) abnormalities were excluded. Overall, 228 patients (7%) had ischemic ECG changes develop during adenosine infusion. Of these, 66 (29% [2% of all patients]) had normal MPI (+ECG group). An age- and sex-matched group of 200 patients with normal MPI without ECG changes served as control subjects (-ECG group). During a mean follow-up of 29 +/- 12 months, patients in the +ECG group had significantly more adverse cardiac events than those in the -ECG group (nonfatal myocardial infarction, 7.6% vs 0.5%, respectively, P = .004; subsequent revascularization, 13.6% vs 2.5%, respectively, P = .0015). Although cardiac death alone did not differ between the 2 groups (+ECG, 3.0%, vs -ECG, 1.0%; P = .25), cumulative survival free from cardiac death and nonfatal myocardial infarction was worse in patients with ST-segment depression during adenosine infusion and normal MPI (+ECG, 10.6%, vs -ECG, 1.5%; log-rank chi(2) = 11.82; P = .0006). CONCLUSIONS: Patients with normal myocardial perfusion images in whom ST-segment depression develops during adenosine administration appear to be at increased risk for future cardiac events compared with similar patients without ECG evidence of ischemia. Ischemic ECG changes during adenosine MPI should warrant further evaluation, even when perfusion images are reassuring.     

Incidence of major cardiovascular events in black patients with normal myocardial stress perfusion study results

BACKGROUND: Previous studies have shown that the risk of major cardiovascular events at 1 year is less than 1% in patients with normal myocardial stress perfusion study results. However, the racial distribution of patients enrolled in these studies is not known. Hence, the prognostic value of normal stress perfusion study results in black patients is not well established. Our objective was to determine the incidence of major cardiovascular events in black patients with normal stress perfusion study results over a 12-month period. METHODS AND RESULTS: We searched the nuclear cardiology database at our institution for all black patients who had normal stress perfusion study results between January 1990 and December 1996. We excluded patients with a history of coronary revascularization, valvular heart disease, cardiomyopathy, congenital heart disease, left bundle branch block, or pre-excitation syndrome. Patients were followed up for at least 12 months from the time of inclusion. A total of 592 patients were enrolled and were followed up for 18 +/- 6 months (mean +/- SD). Of these, 388 underwent treadmill exercise testing, 155 underwent dipyridamole stress testing, and the remainder underwent dobutamine stress testing. Perfusion studies were performed in all patients with thallium 201 single photon emission computed tomography imaging. During the follow-up period, 11 cardiac deaths and 7 myocardial infarctions (MIs) occurred. The incidence of cardiac deaths was 1.2% per year, and that of nonfatal MIs was 0.8% per year. The total incidence of major cardiovascular events was 2% per year. In patients who underwent treadmill exercise testing, the incidence of major cardiovascular events was 1% per year. Performance of a pharmacologic stress test and a prior MI were significantly associated with death or nonfatal MI (P <.05). CONCLUSIONS: The overall incidence of major cardiovascular events in black patients after normal exercise perfusion study results were obtained was low (1%). However, black patients who had normal perfusion study results but underwent pharmacologic stress testing or had a history of MI were at intermediate risk. These patients require close surveillance for major cardiovascular events.     

Prognostic value of adenosine Tl-201 myocardial perfusion imaging after acute myocardial infarction: Results of a prospective clinical trial

BACKGROUND: We have previously shown in retrospective studies that adenosine myocardial perfusion imaging (MPI) done after acute myocardial infarction (AMI) can effectively predict the risk of future cardiac events in these patients. The objective of this study was to validate these observations in a prospective clinical trial. METHODS AND RESULTS: One hundred twenty-six stable patients underwent quantitative adenosine MPI at a mean of 4.5 +/- 2.9 days after AMI. On the basis of the MPI results, they were divided into 3 risk groups: low risk (< 20% perfusion defect), intermediate risk (> or = 20% perfusion defect with < 10% ischemia), and high risk (> or = 20% perfusion defect with > 10% ischemia). The patients were followed up for 11 +/- 5 months for the occurrence of cardiac events: death, myocardial infarction, unstable angina, or congestive heart failure. The actual event rates correlated very well with the prespecified risk groups (19% for the low-risk group, 28% for the intermediate-risk group, and 78% for the high-risk group; P < .001). The significant multivariate predictors for events were female gender (relative risk [RR], 2.90; P = .002), left ventricular ejection fraction (RR, 1.34; P = .04), and ischemic defect size (RR, 1.46; P = .001), with a global chi2 value of 26.7. CONCLUSION: This study demonstrates, in a prospectively designed clinical trial, that quantitative adenosine MPI performed soon after AMI can effectively predict the risk of future cardiac events. These findings are currently being validated in an ongoing, large, multicenter, international clinical trial.     

Head-to-head comparison of prognostic accuracy in patients undergoing noncardiac surgery of dobutamine stress echocardiography versus computed tomography coronary angiography (PANDA trial): A prospective observational study

BackgroundDobutamine stress echocardiography (DSE) and coronary computed tomography angiography (CTA) can provide perioperative prognostic information in risk stratification of patients undergoing noncardiac surgery. This study directly compared the prognostic value of DSE and CTA in patients undergoing noncardiac surgery.MethodsBetween 2014 and 2016, 215 patients with more than one clinical risk factor for perioperative cardiovascular (CV) events were enrolled prospectively. They received both DSE and CTA before noncardiac surgery. Perioperative clinical risk was classified according to the revised cardiac risk index (RCRI), DSE results were categorized as abnormal (inducible ischemia and/or nonviable infarction) or not. CTA results were assessed using the severity of stenosis, with significant stenosis being ≥50% of the luminal diameter). After the exclusion, a total of 206 patients remained. Perioperative CV events were defined as CV death, non-fatal myocardial infarction (MI), myocardial injury, pulmonary edema, non-fatal stroke, and systemic embolism within 30 days after surgery.ResultsTwenty-four patients (12%) had perioperative cardiac events (1 cardiac death, 10 non-fatal MI, 8 myocardial injury, 11 pulmonary edema, 1 non-fatal stroke, and 1 pulmonary embolism). Following adjustment for baseline RCRI score, abnormal result on DSE (OR, 6.08, 95% CI, 2.41 to 15.31, P < 0.001), significant CAD on CTA (OR, 18.79; 95% CI, 5.24 to 67.42, P < 0.001), and high CACS (OR, 4.19; 95% CI, 1.39 to 12.60, P = 0.011) remained significant predictors of perioperative CV events.ConclusionsDSE and CTA are independent predictive factors of events in patients undergoing noncardiac surgery. Among them, assessment of significant CAD using CTA might show a higher prognostic value compared with DSE before noncardiac surgery.Clinical trial registrationURL: http://www.clinicaltrials.gov. Unique identifier: NCT02250963.     

The additive values of left ventricular function and extent of myocardium at risk to dipyridamole perfusion imaging for optimal risk stratification prior to vascular surgery.

Although the increased risk of cardiac complications in surgical patients with diminished left ventricular ejection fraction (LVEF) is well-established, this method has been supplanted in recent years by assessment of ischaemic burden using myocardial perfusion imaging (MPI). This study was conducted to determine if MPI and LVEF determination provide complementary or redundant information in preoperative evaluation of vascular surgery patients. A total of 101 patients were studied with dipyridamole MPI and radionuclide ventriculography before surgery. Single photon emission tomographic MPI images were scored for defect severity and categorized as either fixed or reflecting ischaemia. Resting left ventricular cavity was also categorized as normal or dilated. LVEF was subdivided into normal (> or = 50%) and abnormal (< 50%). Seventeen patients had cardiac events. Events were more frequent in patients with ischaemia, in patients with a LVEF < 50% and in those with dilated left ventricular chambers. The mean number of ischaemic segments was also higher in the cardiac event group. Higher event rates were seen when a combination of these factors was present. A history of myocardial infarct, congestive heart failure or coronary artery disease was also a significant predictor of subsequent events. Thus, both abnormal left ventricular function and extent of ischaemic myocardium have independent and complementary predictive power for cardiac events in vascular surgery patients.     

Prognostic value of stress-gated 99m-technetium SPECT myocardial perfusion imaging: Risk stratification of patients with multivessel coronary artery disease and prior coronary revascularization

Background

This study assessed the prognostic value of stress-gated 99mTc-sestamibi myocardial perfusion SPECT (MPS) in patients with multivessel coronary artery disease (CAD) and prior revascularization according to the presence and severity of ischemia.

Methods and Results

We studied the outcome of 472 patients with multivessel CAD and prior revascularization (coronary angioplasty, 290 patients; bypass surgery, 182 patients), who underwent exercise or dipyridamole 99mTc-sestamibi MPS for evaluation of ischemia. Visual scoring of perfusion images used 20 segments and a 5-point scale. Gated post-stress EF was automatically calculated. Endpoints included hard events: cardiac death (CD) and nonfatal myocardial infarction (MI). During a mean follow-up of 3.0 ± 1.0 years, 37 hard events occurred, including CD in 15 (3%) and MI in 22 (5%) patients. In a risk-adjusted multivariable Cox model, a history of prior MI, diabetes, abnormal MPS, moderate-to-severe ischemia, and post-stress EF <35% were important predictors of cardiac events. Four-year risk-adjusted survival was 97.9% for normal MPS, 87.3% for abnormal MPS with ischemia, and 82.1% for moderate-to-severe ischemia.

Conclusions

Among patients with previous coronary revascularization, stress-gated 99mTc-sestamibi MPS provides prognostic information for the prediction of cardiac events. A normal perfusion scan confers an excellent prognosis and an exceedingly low hard event rate (<1%/year). The presence of moderate-to-severe ischemia or a post-stress EF <35% identifies patients at highest risk of subsequent cardiac events.     

Influence of 99mTc-tetrofosmin SPECT myocardial perfusion imaging on the prediction of future adverse cardiac events

Background  The impact of myocardial perfusion imaging (MPI) on prediction of risk for future cardiac events was examined by comparing predictions based on clinical information alone and in combination with MPI findings. Methods and Results  A 3-cardiologist Cardiac Event Prediction Panel (CEPP) estimated three-year cardiac event (non-fatal MI; aborted sudden cardiac death; cardiac death) risk based on clinical data (C) for 371 subjects. CEPP repeated this estimation after receiving Summed Stress Scores (SSS) and Summed Rest Scores (SRS) from blinded reading of rest-stress ^99mTc-tetrofosmin MPI SPECT studies (C + MPI). The C and C + MPI estimates were then compared with three-year and total event rates. MPI was normal (SSS ≤ 3) in 227 patients (61%), mildly abnormal (SSS 4-8) in 31 (8%), moderately abnormal (SSS 9-13) in 36 (10%), and severely abnormal (SSS > 13) in 77 (21%). Eighteen cardiac events occurred within 3 years and 33 occurred during a mean follow-up of 3.9 years. C + MPI estimates of low risk (<1-1.5%/year) identified significantly more patients who did not have events than C. C + MPI three-year event-rate predictions were more accurate than those made with C (P < .01). C + MPI categorization also provided better delineation of incremental risk on time-to-event analyses. Conclusions   ^99mTc-tetrofosmin MPI single photon emission computed tomography (SPECT) findings significantly improve accuracy of cardiac event rate prediction compared to those based on clinical information alone. This study was performed by GE Healthcare.     

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

BACKGROUND: Little is known about the prognostic value of myocardial perfusion single photon emission computed tomography (SPECT) in patients with remote prior myocardial infarction (MI). METHODS AND RESULTS: We identified 1413 consecutive patients with remote prior MI who underwent rest-stress myocardial perfusion SPECT. Semiquantitative visual analysis of 20 SPECT segments was used to define the summed stress, rest, and difference scores. The number of non-reversible segments was used as an index of infarct size. During follow-up (>or=1 year), 118 hard events occurred: 64 cardiac deaths (CDs) and 54 recurrent MIs. Annual CD and hard event rates increased significantly as a function of SPECT abnormality. For summed stress scores less than 4, 4 to 8, 9 to 13, and more than 13, the annual CD rates were 0.4%, 0.9%, 1.7%, and 3.5%, respectively (P =.002). Patients with small MI (<4 non-reversible segments) and no or mild ischemia (summed difference score or=4 non-reversible segments) had moderate to high annual CD rates (3.7%-6.6%) regardless of the extent of ischemia. Nuclear testing added incremental prognostic information to pre-scan information. Compared with a strategy in which all patients are referred to catheterization, a strategy that referred only those patients with a risk for CD of greater than 1% by myocardial perfusion SPECT resulted in a 41.6% cost savings. CONCLUSIONS: Myocardial perfusion SPECT adds incremental value to pre-scan information and is highly predictive and cost-efficient in the risk stratification of patients with remote prior MI. Patients with normal or mildly abnormal scan results or small MI in combination with absent or mild ischemia have a low risk for CD.     

Bilateral basal Xe-133 retention and ventilation/perfusion patterns in mild and subclinical congestive heart failure

The Xe-133 ventilation pattern in congestive heart failure (CHF) was assessed using 24 inpatient ventilation/perfusion studies performed to rule out pulmonary embolism. Patients with histories of CHF, myocardial infarction (MI), and cardiomyopathy were included in the study. Frank pulmonary edema, pulmonary embolism, and other known lung diseases such as chronic obstructive lung disease, tumor, and pneumonia were excluded. Fifteen of the 24 patients had abnormal ventilation scans. Twelve of the 15 showed bilateral basal Xe-133 retention on washout; the remaining 3 showed diffuse, posterior regional retention. On perfusion scans, 14 of the 15 abnormal ventilation patients showed evidence of CHF such as inverted perfusion gradient, enlarged cardiac silhouette, or patchy perfusion, and all of them had a history of CHF or cardiac disease. Nine of the 24 patients had normal ventilation scans, including normal washout patterns. Seven of the nine had normal perfusion (p less than 0.01). Four of the nine normal ventilation patients had a history of cardiac disease or CHF but no recent acute MI. Bilateral basal regional Xe-133 retention, coupled with perfusion scan evidence of CHF such as inverted perfusion gradient, enlarged cardiac silhouette, and patchy perfusion pattern, appears to be a sensitive and characteristic ventilation/perfusion finding in mild or subclinical CHF.     

Prediction of 14-year cardiovascular outcomes by dobutamine stress <Superscript>99m</Superscript>Tc-tetrofosmin myocardial perfusion SPECT in elderly patients unable to perform exercise testing

Background

Dobutamine stress myocardial perfusion imaging (MPI) is a useful alternative for the evaluation of coronary artery disease (CAD) in elderly patients who are unable to perform an exercise stress test. However, data on the long-term prognostic value of stress MPI in elderly patients are lacking. Therefore, this study evaluated the long-term prognostic value of dobutamine stress MPI in elderly patients unable to perform an exercise test.

Methods

The study population consisted of 247 elderly patients (mean age 71 ± 5 years) who underwent dobutamine stress single-photon emission computed tomography (SPECT) MPI. An abnormal SPECT study was defined as the presence of fixed and/or reversible perfusion defects. A summed stress score (SSS) was obtained to estimate the extent and severity of perfusion defects. End points during follow-up were all-cause mortality, cardiac mortality, and nonfatal myocardial infarction (MI).

Results

During a median follow-up of 14 years (range 12-16), 168 (68%) patients died (all-cause mortality), of which 56 (23%) were due to cardiac causes. Nonfatal MI occurred in 19 (8%) patients. Kaplan-Meier survival curves showed that MPI provided optimal risk stratification in patients with normal and abnormal MPI. Multivariable analysis identified an abnormal MPI as a strong significant predictor of all-cause mortality and cardiac events. A multivariable analysis also revealed that a reversible defect and SSS were strong long-term predictors of cardiac mortality and hard cardiac events.

Conclusion

Dobutamine stress ^99mTc-tetrofosmin SPECT provides incremental prognostic information for the prediction of long-term cardiovascular outcomes in elderly patients, unable to perform exercise testing. Dobutamine stress MPI is useful in risk classifying elderly patients.

     

Electrocardiographic changes during vasodilator SPECT myocardial perfusion imaging: Does it affect diagnosis or prognosis?

Background

Significance of electrocardiographic (ECG) changes during vasodilator stress myocardial perfusion imaging (MPI) is controversial. We examined the diagnostic and prognostic significance of ECG changes during vasodilator single photon emission computerized tomography (SPECT) MPI.

Methods

We studied consecutive patients who underwent vasodilator SPECT MPI from 1995 to 2009. Patients with baseline ECG abnormalities, previous history of coronary artery bypass graft surgery or myocardial infarction (MI) were excluded. Significant coronary artery disease (CAD) was defined as >70% stenosis of any vessel or ??50% stenosis of left main. Mean follow-up was 2.4?±?1.5?years for cardiac events (cardiac death and non-fatal MI).

Results

Of patients in the diagnostic cohort, ST depression was associated with increased incidence of CAD with abnormal (P?=?.020 and P?<.001) but not in those with normal perfusion (P?=?.342). Of 3,566 patients with follow-up in the prognostic cohort, including 130 (5.0%) with ST depression and normal perfusion, the presence of ST depression ??1?mm did not affect the outcomes in any summed stress score category.

Conclusions

ST depression ??1?mm during vasodilator SPECT MPI is associated with CAD in patients with abnormal perfusion, but provides no additional risk stratification beyond concomitant perfusion imaging, including those with normal studies.     

Prognostic value of spect myocardial perfusion imaging in patients with elevated cardiac troponin i levels and atypical clinical presentation

Background  We determined the prognostic value of myocardial perfusion imaging (MPI) in patients with atypical clinical presentations and unexpected elevation of cardiac troponin I (cTnI) levels. Methods and Results  In 156 consecutive patients with atypical presentations for acute coronary syndromes (ACS) and elevated cTnI levels undergoing MPI within 30 days, rates of all-cause mortality (100% follow-up; median follow-up, 611 days) and 6-month cardiac death and nonfatal myocardial infarction (96% follow-up; median follow-up, 167 days) were determined. The mean age of the patients was 68 ± 14 years. The majority of the study cohort (96%) was at low to intermediate clinical risk for ACS (Thrombolysis in Myocardial Infarction score for unstable angina/non-ST-segment elevation myocardial infarction < 5). The overall event rate was high, with 45 deaths (28.8%). There were 13 cardiac deaths/nonfatal myocardial infarctions in 6 months (8.3%). A normal MPI result was associated with a high event-free survival rate, whereas an abnormal MPI result was associated with a 3-fold and 7-fold higher risk of all-cause mortality and 6-month cardiac events, respectively. An abnormal MPI result was an independent predictor of all-cause death. Conclusions  In patients with cTnI elevation and a low to intermediate risk for ACS, a normal MPI result portends a good prognosis. Patients with abnormal MPI results have a higher 6-month cardiac event rate and a worse survival rate.     

Cardiac stress imaging for the prediction of very long-term outcomes: Dobutamine stress echocardiography or dobutamine <Superscript>99m</Superscript>Tc-sestamibi SPECT?

Background

Both dobutamine stress echocardiography (DSE) and myocardial perfusion imaging (MPI) using single-photon emission computed tomography (SPECT) are frequently used for cardiac risk stratification. The long-term relative prognostic value of these modalities has not been studied. Therefore, this study evaluated the long-term prognostic value of DSE compared to MPI in patients unable to perform exercise testing.

Methods

This prospective, single center study included 301 patients (mean age 59 ± 12 years, 56% men) unable to perform exercise tests who underwent DSE and dobutamine stress ^99mTc-sestamibi MPI. End points during follow-up were all-cause mortality, cardiac mortality, and nonfatal myocardial infarction (MI). Univariable and multivariable Cox proportional hazards regression models were used to identify independent predictors of outcome. The probability of survival was calculated using the Kaplan-Meier method.

Results

A total of 182 patients (60%) had an abnormal DSE and 198 (66%) patients had an abnormal MPI. The agreement between DSE and MPI was 82% (κ = 0.62). During a median follow-up of 14 years (range 5-18), 172 deaths (57%) occurred, of which 72 (24%) were due to cardiac causes. Nonfatal MI occurred in 46 patients (15%). The multivariable analysis demonstrated that an abnormal DSE was a significant predictor of cardiac mortality (HR 2.35, 95% CI [1.17-4.73]) and hard cardiac events (HR 2.11, 95% CI [1.25-3.57]). Also, an abnormal MPI result was a significant predictor of cardiac mortality (HR 3.03, 95% CI [1.33-6.95]) and hard cardiac events (HR 2.06, 95% CI [1.12-3.79]).

Conclusions

DSE and MPI are comparable in predicting long-term cardiac mortality and hard cardiac events in patients unable to perform exercise testing.

     

Risk stratification among diabetic patients undergoing stress myocardial perfusion imaging

Background

Previous studies have suggested that diabetic patients undergoing single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) are at greater risk for cardiac events than non-diabetic patients with both normal and abnormal imaging results. However, the impact of stress modality on outcomes in this patient group has not been examined.

Methods

The data on all patients undergoing exercise stress or vasodilator stress SPECT MPI from 1996 to 2005 were reviewed. After excluding patients based on our predefined criteria, we subcategorized the study population into diabetic patients and non-diabetic patients. Among the diabetic patients, we identified patients with known coronary artery disease (CAD) and no known CAD. All studies were interpreted using the 17-segment ASNC model. The presence, extent, and severity of perfusion defects were calculated using the summed stress score (SSS), and patients were classified into normal (SSS < 4), mildly abnormal (SSS 4-8), and moderate-severely abnormal (SSS > 8) categories. The annualized cardiac event rate including cardiac death and non-fatal myocardial infarction was calculated over a mean follow-up period of 2.4 ± 1.4 years with a maximum of 6 years.

Results

The cardiac event rate was statistically significantly lower in diabetic patients undergoing exercise stress MPI when compared to the diabetic patients undergoing pharmacological stress MPI across all three perfusion categories (1.3% vs 3.4%, 2.3% vs 5.7%, 4.2% vs 10.7%, respectively). Diabetic patients with no known CAD, who underwent exercise stress MPI had significantly lower cardiac events across all three perfusion categories as compared to the remainder of the diabetic population. Ability to perform exercise stress test was the strongest multivariate predictor of favorable outcome, whereas ejection fraction < 50%, abnormal perfusion imaging on SPECT MPI, and increasing age stood out as independent predictors of adverse outcome in the diabetic patients. Within the abnormal perfusion category, the annualized cardiac event rate among patients undergoing exercise stress SPECT MPI was not statistically different between the diabetic and non-diabetic cohorts.

Conclusion

Diabetic patients undergoing exercise SPECT MPI have a significantly better prognosis than those undergoing pharmacological stress, more similar to patients without diabetes. In patients with diabetes exercise stress test MPI identifies low risk patients and provides precise risk stratification.