Exercise Myocardial Perfusion Imaging Research Articles

Abstract 12224: Long Term Mortality in Patients With Low-Risk Myocardial Perfusion Imaging

Introduction: Stress testing is utilized for diagnosis and risk stratification for coronary artery disease, with low-risk myocardial perfusion imaging (MPI) indicating less than 1% cardiac mortality per year. We aimed to determine the long-term cardiac mortality in these patients. Methods: We performed a retrospective observational study of 1,300 patients with low-risk MPI in 2015, including pharmacological and exercise studies in a tertiary care center in Central Massachusetts, USA. Each patient was followed from the time of the MPI study for a total duration of 7 years. All-cause mortality and cardiac death were identified. We calculated the pharmacologic and exercise MPI percentage in patients with cardiac death. A cardiac mortality graph was plotted to observe trends over seven years. Results: Out of the 1,300 patients, 3.2% [n=42; mean age 74.6+/-20 years, 78% male (n=32)] of patients had a cardiac death in the follow-up period of 7 years. The pharmacological MPI group had 5% (n=41) cardiac deaths as compared to 0.2% (n=1) in the exercise MPI with the low Duke Treadmill Score group (p-value 0.04) [Figure 1a]. The cardiac death trend over the seven years revealed the highest mortality in year 6 (19%, n= 8) and the lowest in year 4 (7.1%, n=3) [Figure 1b]. Conclusions: The incidence of long-term cardiac deaths is less than 0.5% each year in patients with low-risk MPI, in both groups. Cardiac mortality was higher in patients who underwent pharmacological stress tests indicating appropriate assessment of underlying cardiac pathology. Exercise MPI depends on multiple variables to be optimal, while all patients undergoing pharmacological MPI are maximally stressed. Extensive, multi-center, controlled studies are necessary to evaluate the differences in risk stratification of low-risk MPI between exercise and pharmacological stress tests.

Transient ischaemic dilation ratio thresholds in patients with zero coronary calcium score undergoing exercise or dipyridamole stress SPECT myocardial perfusion imaging using a cadmium-zinc-telluride camera

Abstract Aims Transient ischaemic dilation (TID) is a marker of underlying extensive coronary artery disease (CAD) during myocardial perfusion imaging (MPI). The cut-off for a normal TID ratio (TIDr) value is often derived from a cohort of individuals with no apparent CAD. Varying criteria have been used to define the absence of CAD. We aim to derive TIDr cut-offs using patients with normal MPI and coronary artery calcium (CAC) score of zero, and compare the TIDr obtained from different software packages. Methods and results We studied 232 patients with zero CAC and normal MPI undergoing exercise or dipyridamole stress using either a 1- or 2-day protocol. All patients were scanned in the supine position with a cadmium-zinc-telluride camera. TIDr was automatically generated using quantitative perfusion SPECT (QPS) software initially, and subsequently using Myometrix for comparison. The TIDr cut-offs calculated using the mean + 2 standard deviation were 1.29 and 1.24 for the 1- and 2-day protocol groups, respectively. In patients undergoing a 2-day protocol, dipyridamole stress resulted in significantly higher mean TIDr when compared to exercise stress (1.07 ± 0.13 vs. 1.01 ± 0.12, P = 0.035). Myometrix-derived TIDr were also significantly lower compared to QPS-derived values for most protocols except for 2-day exercise stress. Conclusion This study is the first to derive TIDr threshold values using a normal population defined by zero CAC and normal MPI. TIDr was found to vary depending on stress modality, protocol as well as the software used.

Patients with Polyvascular Disease: A Very High-risk Group.

Polyvascular disease (PolyvascDis) with atherosclerosis occurring in >2 vascular beds (coronary, carotid, aortic, visceral and/or peripheral arteries) is encountered in 15-30% of patients who experience greater rates of major adverse cardiovascular (CV) events. Every patient with multiple CV risk factors or presenting with CV disease in one arterial bed should be assessed for PolyvascDis clinically and noninvasively prior to invasive angiography. Peripheral arterial disease (PAD) can be readily diagnosed in routine practice by measuring the ankle-brachial index. Carotid disease can be diagnosed by duplex ultrasound showing % stenosis and/or presence of plaques. Coronary artery disease (CAD) can be screened by determining coronary artery calcium score using coronary computed tomography angiography; further, non-invasive testing includes exercise stress and/or myocardial perfusion imaging or dobutamine stress test, prior to coronary angiography. Abdominal ultrasound can reveal an abdominal aortic aneurysm. Computed tomography angiography will be needed in patients with suspected mesenteric ischemia to assess the mesenteric arteries. Patients with the acute coronary syndrome and concomitant other arterial diseases have more extensive CAD and poorer CV outcomes. Similarly, PolyvascDis in patients with carotid disease and/or other PAD is independently associated with an increased risk for all-cause and CV mortality during long-term follow-up. Treatment of patients with PolyvascDis should include aggressive management of all modifiable risk factors by lifestyle changes and drug therapy, with particular attention to patients who are commonly undertreated, such as those with PAD. Revascularization should be reserved for symptomatic vascular beds, using the least aggressive strategy in a multidisciplinary vascular team approach.

Role of SPECT Myocardial Perfusion Imaging, in Assessment and Early Diagnosis of Asymptomatic Coronary Artery Disease; An Analytical Study Conducted in a Tertiary Care Hospital of Islamabad, Pakistan

Exercise Tolerance Test (ETT) and Myocardial Perfusion Imaging (MPI) are known non-invasive modalities to detect coronary artery disease (CAD). Aim of this study was to find out better modality for early detection of asymptomatic CAD. Material and Methods: 25 asymptomatic individuals with one or more cardiac risk factors were enrolled. Probability of CAD was calculated, using Framingham scoring; patients classified as low, intermediate and high-risk group. Each (n=25) underwent ETT and MPI. ETT response was categorized as normal, ischemic or equivocal. MPI results as normal, mild, moderate to severe degree defects. 18 patients had follow-up angiograms. Results: Risk stratification showed 14 patients were in intermediate group, 4 had high and 7 had low risk of CAD. In intermediate group, 6 patients had ischemic ETT changes, 10 had perfusion defects on scan and all 10 patients had ≥ 70% stenosis on coronary angiograms. In high-risk group; 2 subjects had positive ETTs, 3 had positive scans and all 3 showed significant vascular involvement on coronary angiogram. In low risk group 3 patients had positive ETT and MPS, 2 had mild vascular stenosis. Considering angiography as gold standard, we observed that MPI had sensitivity (86.66%) and specificity (90%), whereas ETT had 66.6% and 70% respectively. Positive and negative predictive values of MPI were 92.8% and 81.8 % respectively. Post-test probability of MPI was i.e. 0.72-0.88; compared to ETT which was 0.55-0.78. Conclusion: MPI is a better modality than ETT for early diagnosis of occult CAD, especially in intermediate and high risk group.

Mortality risk among patients undergoing exercise versus pharmacologic myocardial perfusion imaging: A propensity-based comparison

Background:The increased risk associated with pharmacologic versus exercise testing is obscured by the higher prevalence of clinical risk factors among pharmacologic patients. Thus, we assessed comparative mortality in a large risk factor-matched group of exercise versus pharmacologic patients undergoing stress/rest SPECT myocardial perfusion imaging (MPI). Methods:39,179 patients undergoing stress/rest SPECT-MPI were followed for 13.3 ± 5.0 years for all-cause mortality (ACM). We applied propensity-matching to create pharmacologic and exercise groups with similar risk profiles. Results:In comparison to exercise patients, pharmacologic patients had an increased risk-adjusted hazard ratio for ACM for each level of ischemia: increased by 3.8-fold (95%CI 3.5-4.1) among nonischemic patients, 2.5-fold (95%CI 2.0-3.2) among mildly ischemic patients, and 2.6-fold (95%CI 2.1-3.3) among moderate/severe ischemic patients. Similar findings were observed among a propensity-matched cohort of 10,113 exercise and 10,113 pharmacologic patients as well as in an additional cohort that also excluded patients with noncardiac co-morbidities. ConclusionsPatients requiring pharmacologic stress testing manifest substantially heightened clinical risk at each level of myocardial ischemia and even when myocardial ischemia is absent. These findings suggest the need to study the pathophysiological drivers of increased risk in association with pharmacologic testing and to convey this risk in clinical reports.

Spleen Perfusion as an Index of Gender Impact on Sympathetic Nervous System Response to Exercise.

Objective: Sympathetic nervous system (SNS) reaction to exercise is gender dependent. Nevertheless, clinically applicable methods to identify this difference are still missing. An organ largely sensitive to SNS is the spleen whose response to exercise can be easily evaluated, being included in the field of view of myocardial perfusion imaging (MPI). Here, we aimed to verify whether gender interferes with the spleen perfusion and its response to exercise.Methods: For this purpose, we evaluated 286 original scans of consecutive patients submitted to MPI in the course of 2019. Our standard procedure implies a single-day stress-rest sequence with a gap of ≥2 h between the administrations of 180 and 500 MBq of 99mTc-Sestamibi, respectively. Imaging is performed 30 min after radiotracer administration, with scan duration set at 25 and 35 s per view, respectively. Non-gated scans were reconstructed with the filtered back-projection method. A volume of interest was drawn on the spleen and heart to estimate the dose-normalized average counting rate that was expressed in normalized counts per seconds (NCPS).Results: In all subjects submitted to exercise MPI (n = 228), NCPS were higher during stress than at rest (3.52 ± 2.03 vs. 2.78 ± 2.07, respectively; p < 0.01). This effect was not detected in the 58 patients submitted to dipyridamole-stress. The response to exercise selectively involved the spleen, since NCPS in heart were unchanged irrespective of the used stressor. This same response was dependent upon gender, indeed spleen NCPS during stress were significantly higher in the 75 women than in the 153 men (3.86 ± 1.8 vs. 3.23 ± 1.6, respectively, p < 0.01). Again, this variance was not reproduced by heart. Finally, spleen NCPS were lower in the 173 patients with myocardial reversible perfusion defects (summed difference score ≥3) than in the remaining 55, despite similar values of rate pressure product at tracer injection.Conclusion: Thus, exercise interference on spleen perfusion can be detected during MPI. This effect is dependent upon gender and ischemia confirming the high sensitivity of this organ to SNS activation.

Association between coronary atherosclerotic burden and all-cause mortality among patients undergoing exercise versus pharmacologic stress-rest SPECT myocardial perfusion imaging

Background and aimsPatients with suspected coronary artery disease who undergo stress SPECT myocardial perfusion imaging (MPI) and require pharmacologic stress are at substantially increased mortality risk compared to those who can exercise. However, the mechanisms underlying this increased risk are not well delineated. To test whether increased atherosclerotic burden accounts for this increased risk, we assessed the association between coronary artery calcium (CAC) scores and mortality risk among patients undergoing exercise versus pharmacologic SPECT MPI. MethodsWe assessed all-cause mortality in 2,151 patients, followed for 12.2 ± 3.4 years, after undergoing stress-rest SPECT-MPI and CAC scanning within 3 months of each other. Patients were divided according to their mode of stress testing (exercise or pharmacologic). We further employed propensity analysis to create a subgroup of exercise and pharmacologic subgroups with comparable age, symptoms, and coronary risk factors. ResultsDespite greater age and worse clinical profiles, pharmacologic and exercise patients had similar CAC scores. However, the hazard ratio (95% CI) for mortality was substantially greater among pharmacologic patients: 2.39 (1.83–3.10). For each level of CAC abnormality, pharmacologic patients had >2-fold increased risk adjusted hazard ratio for all-mortality risk (p < 0.05 for each CAC level). Among propensity-matched exercise versus pharmacologic patients, the same findings were observed. ConclusionsAmong patients referred for stress-rest SPECT-MPI and CAC scoring, pharmacologic patients have substantially increased mortality risk compared to exercise patients, despite having comparable levels of coronary atherosclerosis.

Identifying Subclinical Coronary Abnormalities and Silent Myocardial Ischemia After Arterial Switch Operation.

The incidence of late coronary complications is reported around 8% after arterial switch operation (ASO) for d-transposition of the great arteries, but the affected patients are usually asymptomatic. Exercise stress test (EST) and myocardial perfusion imaging (MPI) are common non-invasive modalities to screen for silent myocardial ischemia, but their diagnostic reliability in children after ASO is unclear. We retrospectively reviewed asymptomatic patients following ASO with EST, MPI, and coronary imaging studies (CIS) and examined the reliability of each test in identifying abnormal coronary lesions responsible for myocardial ischemia. Thirty-seven asymptomatic patients (24 males; ages 12.7 ± 3.7years) had EST, in which 27 and 33 patients also underwent MPI and CIS, respectively. Exercise capacity was comparable to the age- and sex-matched 37 controls. In seven patients with angiographically proven moderate to severe coronary abnormalities, only two patients had positive EST and/or MPI, and five patients were negative including one patient who later developed exercise-induced cardiac arrest due to severe proximal left coronary artery stenosis. Two patients with positive EST or MPI showed no correspondingcoronary abnormalities by CIS. Occurrence of acquired late coronary abnormalities did not correlate with the original coronary anatomy or initial surgical procedures. There is no single reliable method to identify the risk of myocardial ischemia after ASO. Although CIS are regarded as a gold standard, multidisciplinary studies are essential to risk-stratify the potential life-threatening coronary lesions after ASO in children.

Estimated age based on exercise stress testing performance outperforms chronological age in predicting mortality.

We sought to estimate patients' age based on their stress testing exercise performance (A-BEST), and evaluate whether A-BEST would be a better predictor of mortality when compared to chronological age. We included 126,356 consecutive patients referred for exercise (electrocardiography, echocardiography or myocardial perfusion imaging) stress testing at our institution from January 1st, 1991 to February 27th, 2015. Estimated age was computed based on exercise capacity (number of peak estimated metabolic equivalents of task), chronotropic reserve index and heart rate recovery, taking into account patient's gender and medications that affect heart rate. Uni and multivariable Cox models were used to determine the association of A-BEST with mortality. Improvement in predicting mortality using A-BEST compared to chronological age was evaluated with the use of net reclassification improvement and C statistic. Mean age was 53.5 ± 12.6 years and 59% were men. At follow-up (mean duration was 8.7 years), 9929 (8%) died. After adjustment for clinical comorbidities, higher metabolic equivalents of task (adjusted hazard ratio (HR) for mortality 0.71, 95% confidence interval (CI) 0.70-0.72, P < 0.001) and higher chronotropic reserve index (adjusted HR for mortality 0.97, 95% CI 0.96-0.99, P = 0.0135) were associated with improved survival, whereas abnormal heart rate recovery (adjusted HR for mortality 1.53, 95% CI 1.46-1.61, P < 0.001) and higher A-BEST (adjusted HR for mortality 1.05, 95% CI 1.04-1.05, P < 0.001) were associated with higher mortality. When comparing prediction models using A-BEST versus chronological age, a significant increase in the area under the curve was demonstrated if A-BEST was used (0.82 vs. 0.79, P < 0.001). The overall net reclassification improvement was 0.30 ( P < 0.001). Estimated age based on exercise stress testing performance is a better predictor of mortality when compared to chronological age.

The impact of combined cardiopulmonary exercise testing and SPECT myocardial perfusion imaging on downstream evaluation and management

ObjectiveThe diagnostic yield of combined cardiopulmonary exercise testing (CPET) and myocardial perfusion imaging (MPI) in patients referred for stress testing has received limited study. MethodsWe evaluated consecutive patients who underwent combined CPET-MPI at a single tertiary referral center between 2011 and 2015. An abnormal CPET was defined as any of the following: reduced oxygen consumption, cardiac output impairment, or pulmonary impairment. Normal MPI was defined as the absence of resting or stress perfusion defect. The primary study outcome was change in clinical decision-making after CPET-MPI including management of pulmonary disease, management of deconditioning, heart failure management, and referral for cardiac catheterization. Outcomes of patients with normal and abnormal MPI were presented based on the specific CPET abnormality. Results415 patients were included in the study. Of the 269 patients that had normal MPI, 206 (77%) had abnormal CPET. Patients with abnormal CPET and normal MPI, compared with patients that had normal CPET and normal MPI, were more frequently diagnosed with pulmonary disease (11.7% vs 3.2%, P = .04) and deconditioning (33.5% vs 17.4%, P = .01). Of the 146 patients that had abnormal MPI, 128 (88%) had abnormal CPET. Patients with abnormal CPET and abnormal MPI, compared with patients that had normal CPET and abnormal MPI, did not statistically differ with regard to the study outcome. ConclusionAn abnormal CPET, if the MPI was normal, prompted further evaluation and led to management of pulmonary disease and deconditioning.

Variations in the referral patterns to pharmacologic and exercise myocardial perfusion imaging

BackgroundMyocardial perfusion imaging (MPI) is commonly utilized for the non-invasive evaluation of patients with suspected coronary artery disease (CAD). It is either performed with exercise or pharmacologic stress. The objective of this study is to compare the referral patterns and diagnostic findings in patients referred for pharmacologic vs exercise MPI. Methods and ResultsThis was a prospective study of 429 consecutive patients who were referred for MPI at the American University of Beirut Medical Center (23% had pharmacologic stress with dipyridamole and 77% had exercise stress testing). Patients referred to pharmacologic stress were older, had a higher percentage of women, and a higher prevalence of diabetes and hypertension. There were more abnormal scans in the pharmacologic stress group (38% vs 20%, P < 0.001), as well as a higher prevalence of ischemia (21% vs 13%, P < 0.001) and impaired left ventricular function with an ejection fraction < 50% (19% vs 7.9%, P < 0.001). The significant predictors for referral to pharmacologic stress by multivariable logistic regression analysis were older age (OR = 2.01 (1.57–2.57), P < 0.001) and diabetes (OR = 2.04 (1.19–3.49), P = 0.009). ConclusionPatients referred for pharmacologic stress MPI are at a higher risk than those referred for exercise stress MPI with more CAD risk factors, older age, and a higher prevalence of abnormal MPI findings.

Higher event rate in patients with high-risk Duke Treadmill Score despite normal exercise-gated myocardial perfusion imaging.

This prospective study was carried out to find the negative predictive value of various Duke Treadmill Scores (DTSs) in patients with normal myocardial perfusion imaging (MPI). This study was conducted from August 2012 to July 2015, and 603 patients having normal exercise MPIs were included. Patients were followed for 2 years for fatal myocardial infarction (FMI) and nonfatal myocardial infarction (NFMI). Follow-up was not available in 23 patients, leaving a cohort of 583 participants. DTS was low risk (≥5) in 286, intermediate risk (between 4 and − 10) in 211, and high risk (≤−11) in 86 patients. Patients with high- and intermediate-risk DTS were significantly elder than low-risk DTS cohort. Patients with high-risk DTS had significantly higher body mass index with male preponderance compared to other groups. No significant difference was found among three groups regarding modifiable or nonmodifiable risk factors and left ventricular ejection fraction. On follow-up, single FMI was observed in high-risk DTS group (log-rank test value = 5.779, P = 0.056). Five NFMI events were observed in high-risk DTS (94.2% survival; log-rank test value = 19.398, P = 0.0001; significant) as compared to two events each in low- and intermediate-risk DTS (nonsignificant). We conclude that patients with normal exercise MPI and low-to-intermediate risk DTS have significantly low NFMI. High-risk DTS despite normal exercise MPI had high NFMI. Further, validation studies to find the predictive value of symptomatic and asymptomatic ST deviation resulting in high-risk DTS in patients with normal exercise MPI are warranted.

Prognostic value of one millisievert exercise myocardial perfusion imaging in patients without known coronary artery disease

The aim of this study was to assess the prognostic value of normal ultra-low-dose exercise MPI with a CZT camera. Methods1901 consecutive patients without known CAD referred for exercise MPI with 1.8 MBq/kg (0.05 mCi) of Tc99m sestamibi or tetrofosmin and a CZT camera were included prospectively. Patients with an abnormal scan requiring an additional resting image (230) or a submaximal exercise test (271) were excluded. The 1400 remaining patients were followed for 39 months. The primary end-point was cardiac events (cardiac death, nonfatal myocardial infarction, and revascularization). The secondary end-point was noncardiac death. ResultsThe mean injected activity was 145 ± 37 MBq (3.9 ± 1 mCi), the mean acquisition duration was 10 ± 0.7 minutes, and the mean effective dose was 0.91 ± 0.13 mSv. 1288 patients (92%) achieved full follow-up. We observed 22 cardiac events and 16 noncardiac deaths. The annualized rates were equivalent to 0.55% for cardiac events and 0.37% for noncardiac mortality. ConclusionsNormal ultra-low-dose exercise MPI with a CZT camera has a high negative predictive value. The effective dose was less than 1 mSv, and the study thus allays concerns about radiation burden.

Prognostic significance of blood pressure response during vasodilator stress Rb-82 positron emission tomography myocardial perfusion imaging

BackgroundA drop in blood pressure (BP) or blunted BP response is an established high-risk marker during exercise myocardial perfusion imaging (MPI); however, data are sparse regarding the prognostic value of BP response in patients undergoing vasodilator stress rubidium-82 (Rb-82) Positron Emission Tomography (PET) MPI. Methods and ResultsFrom the PET Prognosis Multicenter Registry, a cohort of 3413 patients underwent vasodilator stress Rb-82 PET MPI with dipyridamole or adenosine. We used multivariable Cox proportional hazard regression to analyze the association with mortality of four BP variables: stress minus rest systolic BP (∆SBP), stress minus rest diastolic BP (∆DBP), resting systolic BP (rSBP), and resting diastolic BP (rDBP). Covariates that had univariate P values <.10 were entered into the multivariable model. After median 1.7 years follow-up, 270 patients died. In univariate analyses, ∆SBP (P = .082), rSBP (P = .008), and rDBP (P < .001) were of potential prognostic value (P < .10), but ∆DBP was not (P = .96). After adjustment for other clinical and MPI variables, ∆SBP no longer independently predicted mortality (P = .082); only lower rSBP (P = .026) and lower rDBP (P = .045) remained independently prognostic. ConclusionsIn patients undergoing vasodilator stress MPI, only lower resting BP is an independent predictor of mortality along with other clinical and MPI variables; BP response does not appear to add to risk stratification in these patients.

THE IMPACT OF CARDIOPULMONARY TESTING ON DOWNSTREAM EVALUATION IN PATIENTS WHO UNDERGO MYOCARDIAL PERFUSION IMAGING

Background: The diagnostic yield of combined cardiopulmonary exercise testing (CPET) and myocardial perfusion imaging (MPI) has received limited study. Methods: We included consecutive patients who underwent combined CPET-MPI at a single tertiary referral center. An abnormal CPET test was defined

P.1.012 - N-acylethanolamines attenuate Toll-like receptor (TLR)3-induced neuroinflammation, nociceptive and anxiety-like behaviour in rats

Increased circulating osteoprotegerin (OPG) levels have been associated with the prevalence and severity of coronary artery disease and the risk of cardiovascular death. OPG is a cytokine of the tumor necrosis factor receptor superfamily and is expressed in various cell types in the body, including osteoblasts, inflammatory cells, vascular smooth muscle cells/endothelial cells and cardiomyocytes. The main sources determining OPG levels in the circulation however, are not well understood, and whether reversible myocardial ischemia influences OPG levels are not known. Accordingly, OPG levels were measured in 198 patients referred for exercise stress testing and myocardial perfusion imaging (MPI). In addition OPG levels were measured in 8 healthy control subjects performing a maximal bicycle stress test. Plasma samples were collected before, immediately after, 1.5 h and 4.5 h after exercise stress testing with MPI. OPG levels at baseline were not different in patient with reversible myocardial ischemia (n = 19) and patients without reversible ischemia (n = 179) (4.7 [3.6–5.5] pmol/L vs. 4.3 [3.4–5.2] pmol/L, p = 0.21), and there was an increase in OPG levels immediately after exercise regardless of whether or not the patient had reversible ischemia on MPI (absolute increase: 0.2 [0–0.55] pmol/L vs. 0.3 [0–0.5] pmol/L, p = 0.72). OPG levels also increased immediately after stress in the 8 control subjects (3.5 (3.2–3.8) pmol/L at baseline to 3.8 (3.5–4.7), p = 0.008). In conclusion, OPG levels increase acutely during exercise stress testing, but this increase is likely caused by mechanisms other than myocardial ischemia.

Abstract 13304: Prevalence, Perfusion-Based Markers, and Exercise Manifestations of Right Ventricular Dysfunction Among 2,051 Consecutive Patients Undergoing Exercise Myocardial Perfusion Imaging

Introduction: Right (RV) and left ventricular (LV) performance are linked via common coronary supply: Impact of altered LV perfusion on the RV, and independent influence of RV dysfunction (RV dys ) on effort tolerance are unknown. Methods: The population comprised pts undergoing myocardial perfusion imaging (MPI) and echocardiography (echo) within 1 month (5.5±7.9 days): RV dys was defined via standard echo criteria (TAPSE &lt; 1.6 cm, RV S’ &lt; 10mm/s). MPI was the reference for LV ischemia; effort tolerance was assessed via exercise treadmill testing (ETT) at time of MPI. Results: 2051 pts (64±12 yo, 59%M) were studied; 6% had RV dys on echo. Pts with RV dys had lower LVEF (53±14 vs. 62±9%), larger LV size (55±23 vs. 48±16 ml/m 2 ) and higher PA systolic pressure (34±12 vs 30±7 mmHg; all p&lt;0.01). On MPI, summed stress score was 3 fold higher among pts with RV dys (6.9±8.5 v. 2.7±6.1, p&lt;0.001). LV inferior (0.7±1.7 v. 0.2±1.0, p=0.007) and lateral ischemic defects (1.2±2.6 v. 0.2±1.1, p&lt;0.001) were larger in pts with RV dys (both p&lt;0.01); but anterior defects did not differ (p=NS): Inducible inferior and lateral perfusion defects increased likelihood for RV dys (both p&lt;0.001) independent of LV function and PA pressure. Pts with RV dys had lesser heart rate (α 56±26 vs. 69±24 bpm) and blood pressure augmentation (α 28±31 vs. 41±27mmHg, both p&lt;0.001) during ETT, paralleling lower effort duration (6.7±2.8 vs. 7.9±2.9 min, p&lt;0.001): Effort duration decreased in relation to both LV and RV dys , as evidenced by stepwise decrements among pts with normal biventricular function, isolated LV or RV dys and pts with biventricular dysfunction [ Figure ]: Impaired effort tolerance was independently associated with RV dys (regression coefficient 0.73 [CI 0.14-1.31], p=0.02) and LV dys (0.71 [0.27-1.16], p=0.002), even after controlling for age and β blocker use. Conclusions: LV ischemia in inferior and lateral walls confers increased likelihood for RV dys . RV dys impairs exercise tolerance independent of LV dys .

The value of exercise SPET for the detection of coronary artery steal syndrome secondary to unligated major side branch of left internal mammary artery.

The clinical significance of unligated major left internal mammary artery (LIMA)-side branches (SB) remains controversial in patients with previous coronary artery bypass graft (CABG) surgery. The aim of this study was to investigate the clinical significance of unligated major LIMA-SB by using exercise myocardial perfusion imaging (MPI) with single-photon emission tomography. We conducted a retrospective analysis of 2819 consecutive patients who underwent diagnostic angiography. There were 407 CABG patients with LIMA graft. The demographic, laboratory, pre-angiographic stress test and angiographic data of these patients were collected. A subgroup of patients with unligated major LIMA-SB who were referred to angiography with the diagnosis of stable angina pectoris and positive exercise MPI was identified and divided into two groups for comparison: anterior wall vs non-anterior wall ischemia groups. Among 407 patients with LIMA graft, 112 (27.5%) patients were found to have unligated major LIMA-SB. In a subgroup of patients (n=45) with positive exercise MPI and patent LAD-LIMA system with unligated major LIMA-SB, the median values of diameter and length of unligated major LIMA-SB were statistically higher in anterior wall ischemia group (n=24) compared to non-anterior wall ischemia group (1.8mm vs 0.6mm, P<0.001 and 17.0cm vs 8.0cm, P<0.001, respectively). The cut-off values of unligated major LIMA-SB length and diameter were 11cm and 1.3mm respectively. Unligated major LIMA-SB with a length of ≥11.0cm and a diameter of >1.3cm had 95.8% of sensitivity and 100% of specificity for predicting anterior wall ischemia on exercise MPI. In patients with anterior wall ischemia, summed stress score and summed difference score were improved after percutaneous coil embolization of large unligated major LIMA-SB with ≥11.0cm length and >1.3mm diameter. Large unligated major LIMA-SB with ≥11.0cm length and >1.3mm diameter seems to be a potential source of ischemia in CABG patients. We suggest that exercise MPI might be a first option noninvasive test in evaluating the clinical significance of unligated major LIMA-SB and the effectiveness of embolization therapy.

Influence of cardiac stress protocol on myocardial perfusion imaging accuracy: The role of exercise level on the evaluation of ischemic burden

BackgroundSome specifics of cardiac stress protocols, i.e., stressor used or exercise level achieved, may impact myocardial perfusion imaging (MPI) accuracy. MethodsFour-hundred and seventy-five patients were submitted to MPI and coronary angiography. MPI was performed after exercise (303 patients) or dipyridamole stress (172 patients). A coronary stenosis ≥70% was considered significant. In case of exercise test, a peak heart rate (HR) <85% of the maximal age predicted was considered submaximal and categorized as follows: >75% and <85% (“Group 1”); <75% (“Group 2”). ResultsAt coronary angiography, 312/475 (66%) patients showed significant stenosis. In the overall population, MPI showed a high accuracy in unmasking significant coronary stenosis, independently of the stress protocol adopted (AUC .76 for exercise vs .78 for vasodilator; P = NS). However, in case of an exercise stress test, a significant interaction between peak %HR and MPI diagnostic power was evident. While an elevated accuracy was still maintained in “Group 1” patients (AUC .79; P vs maximal exercise = NS), a significant drop was demonstrated in “Group 2” patients (AUC .66; P vs maximal exercise = .012, and P vs “Group 1” = .042). ConclusionsThe accuracy of MPI is not influenced by the stress protocol adopted. Exercise MPI maintains an elevated accuracy as long as the %HR remains >75%.

The Relation of Arm Exercise Peak Heart Rate to Stress Test Results and Outcome.

Arm exercise is an alternative to pharmacologic stress testing for >50% of patients unable to perform treadmill exercise, but no data exist regarding the effect of attained peak arm exercise heart rate on test sensitivity. Thus, the purpose of this investigation was to characterize the relationship of peak arm exercise heart rate responses to abnormal stress test findings, coronary revascularization, and mortality in patients unable to perform leg exercise. From 1997 until 2002, arm cycle ergometer stress tests were performed in 443 consecutive veterans age 64.1 yr (11.0 yr) (mean (SD)), of whom 253 also underwent myocardial perfusion imaging (MPI). Patients were categorized by frequency distributions of quartiles of percentage age-predicted peak heart rate (APPHR), heart rate reserve (HRR), and peak heart rate-systolic blood pressure product (PRPP). Exercise-induced ST-segment depression, abnormal MPI findings, coronary revascularization, and 12.0-yr (1.3 yr) Kaplan-Meier all-cause and cardiovascular mortality plots were then characterized by quartiles of APPHR, HRR, and PRPP. A reduced frequency of abnormal arm exercise ECG results was associated only with the lowest quartile of APPHR (≤69%) and HRR (≤43%), whereas higher frequency of abnormal MPI findings exhibited an inverse relationship trend with lower APPHR (P = 0.10) and HRR (P = 0.12). There was a strong inverse association of APPHR, HRR, and PRPP with all-cause (all P ≤ 0.01) and cardiovascular (P < 0.05) mortality. The frequency of coronary revascularization was unrelated to APPHR or HRR. Arm exercise ECG stress test sensitivity is only reduced at ≤69% APPHR or ≤43% HRR, whereas arm exercise MPI sensitivity and referral for coronary revascularization after arm exercise stress testing are not adversely affected by even a severely blunted peak heart rate. However, both all-cause mortality and cardiovascular mortality are strongly and inversely related to APPHR and HRR.