Drivers of radiation dose reduction with myocardial perfusion imaging: A large health system experience.

BACKGROUND: Despite increasing emphasis on reducing radiation exposure from myocardial perfusion imaging (MPI), the use of radiation-sparing practices (RSP) at nuclear laboratories remains limited. Defining real-world impact of RSPs on effective radiation dose (E) can potentially further motivate their adoption. METHODS: MPI studies performed between 1/2010 and 12/2016 within a single health system were included. Mean E was compared between sites with 'basic' RSP (defined as elimination of thallium-based protocols and use of stress-only (SO) imaging on conventional single photon emission computed tomography (SPECT) cameras) and those with 'advanced' capabilities (sites that additionally used solid-state detector (SSD) SPECT cameras, advanced post-processing software (APPS) or positron emission tomography (PET) imaging), after matching patients by age, gender, and weight. Contributions of individual RSP to E reduction were determined using multiple linear regression after adjusting for factors affecting tracer dose. RESULTS: Among 55,930 MPI studies performed, the use of advanced RSP was associated with significantly lower mean E compared to basic RSP (7 ± 5.6 mSv and 16 ± 5.4 mSv, respectively; P < 0.001), with a greater likelihood of achieving E < 9 mSv (65.7% vs. 10.8%, respectively; OR 15.8 [95% CI 14 to 17.8]; P < 0.0001). Main driver of E reduction was SO-SSD SPECT (mean reduction = 11.5 mSv), followed by use of SO-SPECT + APPS (mean reduction = 10.1 mSv), ;ET (mean reduction = 9.7 mSv); and elimination of thallium protocols (mean reduction = 9.1 mSv); P < 0.0001 for all comparisons. CONCLUSION: In a natural experiment with implementation of radiation-saving practices at a large health system, stress-only protocols used in conjunction with modern SPECT technologies, the use of PET and elimination of thallium-based protocols were associated with greatest reductions in radiation dose. Availability of several approaches to dose reduction within a health system can facilitate achievement of targeted radiation benchmarks in a greater number of performed studies.

Diagnosis and Prognosis of Coronary Artery Disease with SPECT and PET.

PURPOSE OF REVIEW: Radionuclide myocardial perfusion imaging (MPI) continues to be the most reliable modality for diagnosis of hemodynamically significant coronary artery disease (CAD). The application of radionuclide MPI using single photon emission computed tomography (SEPCT) and positron emission tomography (PET) for CAD is reviewed, with emphasis on diagnosis and risk stratification. RECENT FINDINGS: Contemporary studies have reported the diagnostic and prognostic value of novel imaging protocols, employing stress-first or stress-only approach. In addition, the superior diagnostic value of PET has been established with a role of assessment of myocardial blood flow to improve risk stratification. The utility of MPI in special populations, such as the elderly, women, and diabetic patients has also been recently evaluated. Furthermore, multicenter studies have reported a similar diagnostic and prognostic value of radionuclide MPI compared with other functional and anatomical techniques for CAD. Radionuclide MPI with SPECT and PET are efficacious for diagnosis and prognosis of CAD. Its universal application in varied patient populations highlights its excellent clinical effectiveness.

The utility of ADMIRE-HF risk score in predicting serious arrhythmic events in heart failure patients: incremental prognostic benefit of cardiac 123I-mIBG scintigraphy.

BACKGROUND: A minority of heart failure (HF) patients who undergo implantable cardioverter defibrillator (ICD) implantation for primary prevention of sudden cardiac death (SCD) receive device therapy. Whether the addition of mIBG scintigraphy to conventional markers of arrhythmic risk can provide incremental risk stratification in HF patients has not been investigated. METHODS: We identified 778 patients from the ADMIRE-HF study with LVEF < 35% and class II or III HF symptoms who did not have an ICD at the time of enrollment. Patients were followed up prospectively (median 5 17 months) for occurrence of arrhythmic events (ArE). Heart-to-mediastinum ratio (HMR) was determined as a measure of relative myocardial sympathetic nerve activity at baseline using 123I-mIBG. The primary endpoint was the first occurrence of ArE: a composite of SCD, appropriate ICD therapy, resuscitated cardiac arrest or sustained ventricular tachycardia. Multivariate regression was used to determine independent predictors of ArE and to derive a risk score for ArE prediction. The score was used to group patients according to their risk for ArE. Integrated discrimination improvement (IDI) was used to quantify improvement in risk assessment with addition of HMR. RESULTS: ArE occurred in 54 patients (6.9%). ArE predictors were:HMR < 1.6 (HR 3.5, 95%CI [1.52-8], P 5 .02), LVEF < 25% (HR 2.0, 95% CI [1.28-3.05], P 5 .04) and SBP < 120 (HR 1.2,95%CI [1.03-1.39], P 5 .02). Event rates in the low-, intermediate-, and high risk groups were 2, 10 and 16%, respectively (P 5 .001). The score significantly improved risk prediction(IDI 5 45%, P 0.03). CONCLUSION: 123I-mIBG significantly provides incremental risk stratification for ArE in HF patients.

Initiation of statin therapy after acute myocardial infarction is not associated with worsening depressive symptoms: insights from the Prospective Registry Evaluating Outcomes After Myocardial Infarctions: Events and Recovery (PREMIER) and Translational Research Investigating Underlying Disparities in Acute Myocardial Infarction Patients' Health Status (TRIUMPH) registries.

BACKGROUND: Whereas statins are considered the cornerstone of prevention after acute myocardial infarction (AMI), concerns about worsening depression in association with their use have been raised. METHODS: Using data from 2 prospective AMI registries (PREMIER and TRIUMPH), we examined the change in depressive symptoms from baseline and at 1, 6 and 12 months among statin-naïve patients who were and were not discharged on a statin. Depressive symptoms were assessed with the 8-item Patient Health Questionnaire (PHQ-8). Within-group change in PHQ-8 scores from baseline to each follow-up period was assessed using paired t tests. A repeated-measures propensity-matched analysis examined whether changes in PHQ-8 scores from baseline were different between statin-treated and statin-untreated patients. RESULTS: Of 3,675 patients not previously treated with statins, 3,050 (83%) were discharged on a statin and 625 (17%) were not. Scores of PHQ-8 in the statin group decreased from baseline by a mean (± SD) of 0.9 (± 5.1), 1.2 (± 5), and 1.1 (± 5.1) at 1, 6, and 12 months, respectively. Corresponding changes in the nonstatin group were 0.9 (± 5.2), 1.3 (± 5.1), and 1.5 (± 5.8), respectively (P < .0001 for all comparisons). After propensity matching, 451 patients not discharged on statins with 1,240 patients discharged on statins, the mean change in PHQ-8 scores between baseline and the 3 follow-up time points was not significantly different between groups (mean between-group difference at 1 month: -0.13, 95% CI [-0.69 to 0.43], P = .65; at 6 months: -0.07, 95% CI [-0.66 to 0.52], P = .82; and at 12 months: -0.05, 95% CI [-0.67 to 0.58], P = .88). CONCLUSIONS: Initiation of statins after AMI was not associated with worsening depression.

Red yeast rice for dysipidemia.

Red yeast rice is an ancient Chinese food product that contains monacolins, chemical substances that are similar to statins in their mechanisms of action and lipid lowering properties. Several studies have found red yeast rice to be moderately effective at improving the lipid profile, particularly for lowering the low-density lipoprotein cholesterol levels. One large randomized controlled study from China found that red yeast rice significantly improved risk of major adverse cardiovascular events and overall survival in patients following myocardial infarction. Thus, red yeast rice is a potentially useful over-the-counter cholesterol-lowering agent. However, many red yeast rice formulations are non-standardized and unregulated food supplements, and there is a need for further research and regulation of production.

Temporal trends in test utilization and prevalence of ischaemia with positron emission tomography myocardial perfusion imaging.

AIMS: To examine whether test utilization and prevalence of ischemia with positron emission tomography (PET) myocardial perfusion imaging (MPI) follow the previously described trends with single photon computed tomography (SPECT). METHODS AND RESULTS: MPI studies performed between January 2003 and December 2017 were identified. Number of PET and SPECT MPI studies performed per year was determined. Trends in the proportion of studies showing any ischaemia (>0%) with both modalities were compared before and after adjusting for baseline differences in patient characteristics using propensity scores. Interaction between imaging modality and year of testing was examined using modified Poisson regression. A total of 156 244 MPI studies were performed (30% PET and 70% SPECT). Between 2003 and 2017, the number of PET studies increased from 18 to 61 studies/1000 patient encounters, while SPECT volumes declined from 169 to 34/1000 patient encounters (P < 0.001 for within-group comparisons). The prevalence of any ischaemia in SPECT-tested patients declined from 53.9% to 28.3% between 2003 and 2017, whereas ischaemia prevalence in PET-tested patients declined from 57.2% to 38.2% (P < 0.001 for within-modality comparisons), with more PET studies showing ischaemia compared to SPECT [relative risk (RR) 1.44, 95% confidence interval (CI) 1.42-1.47; P < 0.001]. After propensity score matching of 26 066 patients tested with SPECT with 26 066 patients tested with PET, the between-modality difference in ischaemia prevalence was significantly attenuated, with a slightly higher overall likelihood of detecting ischaemia with PET compared to SPECT (RR 1.08, 95% CI 1.05-1.11; P < 0.001). CONCLUSIONS: Utilization of PET MPI at a large-volume referral centre increased significantly between 2003 and 2017. Despite a significant decrease in the prevalence of ischaemia with SPECT and PET during the same period, the decline was less with PET, perhaps related to baseline risk of tested patients.

Meta-analysis of effect of dipeptidyl peptidase-4 inhibitors on cardiovascular risk in type 2 diabetes mellitus.

Patients with type 2 diabetes mellitus (DM) have a very high risk for major adverse cardiovascular (CV) events. Previous studies have shown that traditional oral diabetic medications, despite lowering blood glucose levels, generally do not improve CV outcomes. The safety of some oral hypoglycemic medications has been questioned. We aimed to evaluate the CV safety of dipeptidyl peptidase-4 (DPP4) inhibitors, a novel class of oral diabetic medications, by performing a meta-analysis of DPP4 inhibitors for type 2 DM. A search of electronic databases of published and unpublished literature (until September 30, 2011) was performed to identify randomized controlled trials of ≥24 weeks that compared DPP4 inhibitors to other oral diabetic medications. A meta-analysis was performed using fixed and random effects to determine risk ratio (RR) for adverse CV events with DPP4 inhibitor monotherapy compared to other oral diabetic medications or to placebo. Eighteen randomized met our inclusion criteria, comprising 4,998 patients who were randomized to DPP4 inhibitors and 3,546 to a comparator, with a median duration of therapy of 46.4 weeks. In pooled analysis, the RR of any adverse CV event with a DPP4 inhibitor was 0.48 (0.31 to 0.75, p = 0.001), and the RR for nonfatal myocardial infarction or acute coronary syndrome was 0.40 (0.18 to 0.88, p = 0.02). In conclusion, this meta-analysis provides evidence that DPP4 inhibitors are safe from a CV standpoint and may possibly decrease risk of adverse CV events.

Likelihood of obstructive coronary disease in metabolic syndrome patients with abnormal stress echocardiography.

BACKGROUND: Metabolic syndrome (MetSx) encompasses several risk factors for macrovascular coronary artery disease. An association between MetSx and coronary syndrome X has also been reported, suggesting that patients with MetSx are more likely to have endothelial dysfunction in the setting of angiographically normal coronary arteries. It remains unknown whether MetSx patients with abnormal stress echocardiography (SE) are more likely to have obstructive coronary disease (CAD) compared to patients without MetSx. METHODS: We identified symptomatic patients without known CAD and abnormal SE who underwent coronary angiography within 4 weeks after the SE. Patients were grouped according to their MetSx and impaired fasting glucose (IFG) status. We compared the proportion of patients with obstructive CAD in each subgroup using the x(2) test. Multivariate regression analysis was used to adjust for the pre-test probability of underlying coronary artery disease. RESULTS: Among 583 consecutive symptomatic patients who had an abnormal SE and were referred for angiography, 158 (36%) met the NCEP definition of MetSx. MetSx patients had a trend towards having more obstructive CAD than those without MetSx (OR 1.44, p = 0.07). After adjusting for pre-test probability of coronary disease, smoking and LDL-C, MetSx/IFG combination was an independent predictor of obstructive CAD (OR 2.06 [1.24-3.44], p < 0.001) but MetSx with normal fasting blood glucose was not (OR 0.91 [0.47-1.70], p 0.09). CONCLUSION: Symptomatic patients with MetSx and IFG are more likely to have angiographically significant CAD after abnormal SE than patients without MetSx or those with normal fasting blood glucose.

Evidence-based diuretic therapy for improving cardiovascular prognosis in systemic hypertension.

Diuretics are among the most commonly prescribed cardiovascular (CV) medications. The strength of evidence supporting the effectiveness of diuretics in lowering blood pressure and for preventing major adverse CV events in patients with hypertension varies considerably among diuretic classes and even among agents within the same class. Unfortunately, common prescribing habits among American physicians, including specialists in CV diseases, are not in line with the existing evidence regarding diuretic therapy for improving CV prognosis. In conclusion, although hydrochlorothiazide is the standard diuretic used for hypertension, the outcomes data suggest that chlorthalidone, indapamide, and possibly even the aldosterone receptor blockers (spironolactone and eplerenone) may be superior agents.

Iodixanol versus low-osmolar contrast media for prevention of contrast induced nephropathy: meta-analysis of randomized, controlled trials.

BACKGROUND: Contrast-induced nephropathy (CIN) is associated with significant morbidity and mortality. The objective of our meta-analysis was to assess the efficacy of iodixanol compared with low-osmolar contrast media (LOCM) for prevention of CIN. METHODS AND RESULTS: We searched MEDLINE, the Cochrane Central Register of Controlled Trials, and internet sources of cardiology trial results for individual and relevant reviews of randomized, controlled trials, for the terms contrast media, contrast nephropathy, renal failure, iodixanol, Visipaque, and low-osmolar contrast media. All studies reported an incidence rate of CIN for each study group; there was no restriction on the definition of CIN. There were no restrictions on journal type or patient population. Overall, 36 trials were identified for analysis of aggregated summary data on 7166 patients; 3672 patients received iodixanol and 3494 patients received LOCM. Overall, iodixanol showed no statistically significant reduction in CIN incidence below that observed with heterogeneous comparator agents (P=0.11). Analysis of patient subgroups revealed that there was a significant benefit of iodixanol when compared with iohexol alone (odds ratio, 0.25; 95% confidence interval, 0.11 to 0.55; P<0.001) but not when compared with LOCM other than iohexol or with other ionic dimers or among patients receiving intra-arterial contrast injections or among patients undergoing coronary angiography with or without percutaneous intervention. CONCLUSIONS: Analysis of aggregated summary data from multiple randomized, controlled trials of iodixanol against diverse LOCMs for heterogeneous procedures and definitions of CIN show an iodixanol-associated reduction that is suggestive but statistically nonsignificant.

Percutaneous coronary intervention with drug-eluting stents versus coronary artery bypass surgery for multivessel coronary artery disease: a meta-analysis of data from the ARTS II, CARDia, ERACI III, and SYNTAX studies and systematic review of observational data.

AIMS: The aim of this study was to systematically analyse the available data from trials comparing revascularisation by drug-eluting stent (DES) placement versus coronary artery bypass grafting (CABG) in patients with multivessel coronary artery disease (CAD). METHODS AND RESULTS: We searched PubMed, Medline and several internet sources for randomised controlled trials comparing DES placement to CABG in patients with multivessel coronary artery disease. There were no restrictions on journal type or population studied. Prior to data collection we chose to analyse the prospectively performed trials separately from data obtained retrospectively. Four prospective trials were identified which enrolled a total of 3,895 patients: 1,914 in the DES arm and 1,981 patients in the CABG arm. Pooled analysis of data from these four studies showed that in patients treated DES compared to CABG there was a similar risk of the combined endpoints of death, myocardial infarction and stroke (10.2% versus 10.8%, respectively; RR=0.94 [95% CI=0.77-1.116]; p=0.56), but a significantly higher risk of target vessel revascularisation (TVR) (14.6% versus 6.8%, respectively; RR=2.09 [95% CI=1.72-2.55]; <0.001) and, therefore, a significantly higher risk of MACCE (21.2% versus 16.3%, respectively; RR=1.27 [95% CI=1.09-1.48]; p=0.002). Interestingly, when MACCE rates at one year are used for these trials the risk is equivalent between DES and CABG (14.4% versus 12.5%, respectively; RR=1.05 [95% CI=0.70-1.57]; p=0.83). Analysis of observational data revealed similar findings. CONCLUSIONS: Overall, PCI with DES placement was safe in patients with multivessel disease compared to CABG, but is associated with a significantly higher risk of TVR.

Impact of ezetimibe on atherosclerosis: is the jury still out?

Ezetimibe is a new lipid-lowering agent that inhibits intestinal absorption of dietary cholesterol. It substantially lowers low-density lipoprotein cholesterol levels when used alone or in combination with statins. However, its effect on cardiovascular mortality remains unknown. We reviewed peer-reviewed published literature on the effect of ezetimibe on different phases of atherosclerosis. MEDLINE, EMBASE, BIOSIS, and other Web of Knowledge databases were searched for relevant abstracts and articles published in the English language that compared ezetimibe and statins as modulators of atherosclerosis. On the basis of the available evidence, ezetimibe appears to reduce inflammation when used in combination with statins, but its effect on endothelial function is mixed and less clear. The effect of ezetimibe on coronary disease progression or prevention of cardiovascular events is currently unknown. Use of ezetimibe as a second- or third-line agent to achieve low-density lipoprotein cholesterol treatment goals seems appropriate on the basis of the available evidence.