Optimizing conduction system pacing lead placement utilizing the image overlay technique.

The His-bundle has several locations from which conduction system pacing can be achieved. Some locations offer better sensing, thresholds and paced QRS durations. Existing techniques to aid repositioning of an already deployed, but sub-optimally placed lead, include either simple memory of the initial lead position combined with its observation on an x-ray review screen or utilizing an additional vascular access and pacing lead with the first lead serving as a real-time marker (Two-lead technique). We describe a novel, readily available, cost-efficient, imaging-based approach to assist in the re-positioning of a pacing lead for His-bundle pacing (the Image Overlay Technique).

NT-proBNP/BNP ratio for prognostication in European Caucasian patients enrolled in a heart failure prevention programme.

AIMS: Guidelines support the role of B-type natriuretic peptide (BNP) and amino-terminal pro-BNP (NT-proBNP) for risk stratification of patients in programmes to prevent heart failure (HF). Although biologically formed in a 1:1 ratio, the ratio of NT-proBNP to BNP exhibits wide inter-individual variability. A report on an Asian population suggests that molar NT-proBNP/BNP ratio is associated with incident HF. This study aims to determine whether routine, simultaneous evaluation of both BNP and NT-proBNP is warranted in a European, Caucasian population. METHODS AND RESULTS: We determined BNP and NT-proBNP levels for 782 Stage A/B HF patients in the STOP-HF programme. The clinical, echocardiographic, and biochemical associates of molar NT-proBNP/BNP ratio were analysed. The primary endpoint was the adjusted association of baseline molar NT-proBNP/BNP ratio with new-onset HF and/or progression of left ventricular dysfunction (LVD). We estimated the C-statistic, integrated discrimination improvement, and the category-free net reclassification improvement metric for the addition of molar NT-proBNP/BNP ratio to adjusted models. The median age was 66.6 years [interquartile range (IQR) 59.5-73.1], 371 (47.4%) were female, and median molar NT-proBNP/BNP ratio was 1.91 (IQR 1.37-2.93). Estimated glomerular filtration rate, systolic blood pressure, left ventricular mass index, and heart rate were associated with NT-proBNP/BNP ratio in a linear regression model (all P < 0.05). Over a median follow-up period of 5 years (IQR 3.4-6.8), 247 (31.5%) patients developed HF or progression of LVD. Log-transformed NT-proBNP/BNP ratio is inversely associated with HF and LVD risk when adjusted for age, gender, diabetes, hypertension, vascular disease, obesity, heart rate, number of years of follow-up, estimated glomerular filtration rate, and baseline NT-proBNP (odds ratio 0.71, 95% confidence interval 0.55-0.91; P = 0.008). However, molar NT-proBNP/BNP ratio did not increase the C-statistic (Δ -0.01) and net reclassification improvement (0.0035) for prediction of HF and LVD compared with NT-proBNP or BNP alone. Substitution of NT-proBNP for BNP in the multivariable model eliminated the association with HF and LVD risk. CONCLUSIONS: This study characterized, for the first time in a Caucasian Stage A/B HF population, the relationship between NT-proBNP/BNP ratio and biological factors and demonstrated an inverse relationship with the future development of HF and LVD. However, this study does not support routine simultaneous BNP and NT-proBNP measurement in HF prevention programmes amongst European, Caucasian patients.

Angiotensin Receptor Neprilysin Inhibitors in HFrEF: Is This the First Disease Modifying Therapy Drug Class Leading to a Substantial Reduction in Diuretic Need?

Despite significant advances in disease modifying therapy in heart failure (HF), diuretics have remained the cornerstone of volume management in all HF phenotypes. Diuretics, alongside their definite acute haemodynamic and symptomatic benefits, also possess many possible deleterious side effects. Moreover, questions remain regarding the prognostic impact of chronic diuretic use. To date, few data exist pertaining to diuretic reduction as a result of individual traditional guideline directed medical therapy in HF with reduced ejection fraction (HFrEF). However, diuretic reduction has been demonstrated with sacubitril/valsartan (angiotensin receptor-neprilysin inhibitor [ARNi]) from the PARADIGM study, as well as, post-marketing reports from our own group and others. Whether the ARNi compound represents the dawn of a new era, where effective therapies will have a more noticeable reduction on diuretic need, remains to be seen. The emergence of sodium glucose transport 2 inhibitors and guanylate cyclase stimulators may further exemplify this issue and potentially extend this benefit to HF patients outside of the HFrEF phenotype. In conclusion, emerging new therapies in HFrEF could reduce the reliance on diuretics in the management of this phenotype of HF. These developments further highlight the clinical importance to continually assess an individual's diuretic requirements through careful volume assessment.

Changing to remote management of a community heart failure population during COVID-19 - Clinician and patient perspectives'.

BACKGROUND: The COVID pandemic has challenged the traditional methods used in care of patients with heart failure (HF). Remote management of HF patients has been recommended in order to maintain routine standards of care, but satisfaction with this platform of care is unknown. We set out to address the physician and patient opinion of remote management of HF during COVID-19. METHODS AND RESULTS: An observational report of the use of a Structured Telephonic assessment (STA) in stable outpatient HF patients. Physician grading of the STA was complemented by 100 randomly chosen patients to ascertain patient satisfaction and comment. 278 patients underwent a STA. Patient preference for STA was noted in 66%. Convenience was the single most cited reason for this preference (83.3%). The STA was deemed satisfactory by clinicians in 67.6%. The two-leading reasons for clinician dissatisfaction were data gaps providing a barrier to titration (55.6%) and need for clinical exam (18.9%). The annual review appointment visit subtype possessed the highest levels of satisfaction congruence amongst both clinicians and patients. CONCLUSION: In summary, this report demonstrates reasonable patient / physician satisfaction with STA, and provides some direction on how this care platform might be sustained beyond the COVID crisis.

Sacubitril-Valsartan in a routine community population: attention to volume status critical to achieving target dose.

AIMS: In the PARADIGM-heart failure trial, sacubitril-valsartan demonstrated a reduction in heart failure admissions and reduced all-cause mortality in patients with heart failure with reduced ejection fraction. Although real world data have shown similar benefits regarding efficacy and safety, there has been difficulty in achieving the target dose (TD). The factors preventing the achievement of TD remains unclear. This study assesses the tolerability, ability to achieve, and factors linked to attaining TD in a routine clinical population. METHODS AND RESULTS: This is a retrospective single-centre review of patients switched from angiotensin-converting enzyme inhibitors/angiotensin receptor blockers to sacubitril-valsartan between May 2016 and August 2018. Baseline and follow-up clinical characteristics and biomarker profiles were collected. Univariate and multivariate analyses were used to analyse predictors of achieving TD. Clinical response to sacubitril-valsartan was defined as a reduction in N terminal pro BNP of ≥30%, or an increase in left ventricular ejection fraction of ≥5% compared with baseline values. To date, a total of 322 patients (75% male patients) have been switched to sacubitril-valsartan. Those still in the titration phase were excluded (n = 25). Sacubitril-valsartan was not tolerated in 40 patients (12.4%). Those intolerant were older (73.4 years [68.3, 80.6] vs. 69.1 years [61.2, 76]; P = 0.003) and had worse renal function with estimated glomerular filtration rate (53.5 mL/min/1.72 m2 [36.8, 60.2] vs 60 mL/min/1.72 m2 [47, 77]; P ≤ 0.001). Of the remaining 257 patients, TD (97/103 mg BD) was achieved in 194 patients (75.5%), while 37 patients (11.4%) were maintained on 49/51 mg BD and 26 patients (8.1%) remained on 24/26 mg BD. Symptomatic hypotension (74.6%) was the main impediment to attaining TD, followed by renal deterioration (12.7%), and to a lesser extent hyperkalaemia and gastrointestinal symptoms (4.8% each). Diuretic dose decrease was achieved in 37.2% of patients, and this was the strongest independent predictor of achieving TD (odds ratio = 2.1; 95% confidence interval [1.16, 3.8]; P = 0.014). Responder status by N terminal pro BNP criterion was observed in 99 of 214 patients (46.3%) while 70 of 142 (49.3%) attained the left ventricular ejection fraction response status. Achieving this response was independently linked to achieving TD. CONCLUSIONS: Sacubitril-valsartan was well tolerated. Achievement of TD was possible in the majority of the cohort and was linked to response metrics. Reduction in diuretic was required in a large percentage of the population and was the strongest predictor of attaining TD. Therefore, careful clinical attention to volume status assessment is essential to maximising the benefits of sacubitril-valsartan.

Natriuretic peptide-guided treatment for the prevention of cardiovascular events in patients without heart failure.

BACKGROUND: Cardiovascular disease (CVD) is the leading cause of morbidity and mortality globally. Early intervention for those with high cardiovascular risk is crucial in improving patient outcomes. Traditional prevention strategies for CVD have focused on conventional risk factors, such as overweight, dyslipidaemia, diabetes, and hypertension, which may reflect the potential for cardiovascular insult. Natriuretic peptides (NPs), including B-type natriuretic peptide (BNP) and N-terminal pro B-type natriuretic peptide (NT-proBNP), are well-established biomarkers for the detection and diagnostic evaluation of heart failure. They are of interest for CVD prevention because they are secreted by the heart as a protective response to cardiovascular stress, strain, and damage. Therefore, measuring NP levels in patients without heart failure may be valuable for risk stratification, to identify those at highest risk of CVD who would benefit most from intensive risk reduction measures. OBJECTIVES: To assess the effects of natriuretic peptide (NP)-guided treatment for people with cardiovascular risk factors and without heart failure. SEARCH METHODS: Searches of the following bibliographic databases were conducted up to 9 July 2019: CENTRAL, MEDLINE, Embase, and Web of Science. Three clinical trial registries were also searched in July 2019. SELECTION CRITERIA: We included randomised controlled trials enrolling adults with one or more cardiovascular risk factors and without heart failure, which compared NP-based screening and subsequent NP-guided treatment versus standard care in all settings (i.e. community, hospital). DATA COLLECTION AND ANALYSIS: Two review authors independently screened titles and abstracts and selected studies for inclusion, extracted data, and evaluated risk of bias. Risk ratios (RRs) were calculated for dichotomous data, and mean differences (MDs) with 95% confidence intervals (CIs) were calculated for continuous data. We contacted trial authors to obtain missing data and to verify crucial study characteristics. Using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, two review authors independently assessed the quality of the evidence and GRADE profiler (GRADEPRO) was used to import data from Review Manager to create a 'Summary of findings' table. MAIN RESULTS: We included two randomised controlled trials (three reports) with 1674 participants, with mean age between 64.1 and 67.8 years. Follow-up ranged from 2 years to mean 4.3 years.For primary outcome measures, effect estimates from a single study showed uncertainty for the effect of NP-guided treatment on cardiovascular mortality in patients with cardiovascular risk factors and without heart failure (RR 0.33, 95% CI 0.04 to 3.17; 1 study; 300 participants; low-quality evidence). Pooled analysis demonstrated that in comparison to standard care, NP-guided treatment probably reduces the risk of cardiovascular hospitalisation (RR 0.52, 95% CI 0.40 to 0.68; 2 studies; 1674 participants; moderate-quality evidence). This corresponds to a risk of 163 per 1000 in the control group and 85 (95% CI 65 to 111) per 1000 in the NP-guided treatment group.When secondary outcome measures were evaluated, evidence from a pooled analysis showed uncertainty for the effect of NP-guided treatment on all-cause mortality (RR 0.90, 95% CI 0.60 to 1.35; 2 studies; 1354 participants; low-quality evidence). Pooled analysis indicates that NP-guided treatment probably reduces the risk of all-cause hospitalisation (RR 0.83, 95% CI 0.75 to 0.92; 2 studies; 1354 participants; moderate-quality evidence). This corresponds to a risk of 601 per 1000 in the control group and 499 (95% CI 457 to 553) per 1000 in the NP-guided treatment group. The effect estimate from a single study indicates that NP-guided treatment reduced the risk of ventricular dysfunction (RR 0.61, 95% CI 0.41 to 0.91; 1374 participants; high-quality evidence). The risk in this study's control group was 87 per 1000, compared with 53 (95% CI 36 to 79) per 1000 with NP-guided treatment. Results from the same study show that NP-guided treatment does not affect change in NP level at the end of follow-up, relative to standard care (MD -4.06 pg/mL, 95% CI -15.07 to 6.95; 1 study; 1374 participants; moderate-quality evidence). AUTHORS' CONCLUSIONS: This review shows that NP-guided treatment is likely to reduce ventricular dysfunction and cardiovascular and all-cause hospitalisation for patients who have cardiovascular risk factors and who do not have heart failure. Effects on mortality and natriuretic peptide levels are less certain. Neither of the included studies were powered to evaluate mortality. Available evidence shows uncertainty regarding the effects of NP-guided treatment on both cardiovascular mortality and all-cause mortality; very low event numbers resulted in a high degree of imprecision in these effect estimates. Evidence also shows that NP-guided treatment may not affect NP level at the end of follow-up.As both trials included in our review were pragmatic studies, non-blinding of patients and practices may have biased results towards a finding of equivalence. Further studies with more adequately powered sample sizes and longer duration of follow-up are required to evaluate the effect of NP-guided treatment on mortality. As two trials are ongoing, one of which is a large multi-centre trial, it is hoped that future iterations of this review will benefit from larger sample sizes across a wider geographical area.

Latest Updates on Lipid Management.

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death worldwide. Despite the clinical long-term and near-term benefits of lowering cholesterol in, respectively, primary and secondary prevention of ASCVD, cholesterol levels remain under-treated, with many patients not achieving their recommended targets. The present article will review the latest updates on lipid management with emphases on the different classes of cholesterol-lowering agents and their clinical uses.

Is the prescription right? A review of non-vitamin K antagonist anticoagulant (NOAC) prescriptions in patients with non-valvular atrial fibrillation. Safe prescribing in atrial fibrillation and evaluation of non-vitamin K oral anticoagulants in stroke prevention (SAFE-NOACS) group.

BACKGROUND: Non-vitamin K antagonist oral anticoagulants (NOACs) are a major advance for stroke prevention in atrial fibrillation (AF). Use of the vitamin K antagonist (VKA), warfarin, has dropped 40% since 2010 in our institution. There is limited Irish hospital data on NOAC prescribing for stroke prevention. METHOD: Single centre, retrospective observational cohort study of consecutive AF patients at increased risk of stroke and/or awaiting electrical cardioversion. Data on prescribed NOACs from February 2010 till July 2015 was collected from the electronic inpatient record. Appropriateness of prescriptions was based on CHA2DS2-VASC score and accuracy on individual NOAC SPCs. Potential drug interactions and bleeding risk were also quantified. RESULTS: A total of 348 patients AF and increased risk of stroke (CHA2DS2-VASC score > 1 for men and > 2 for women) were studied. Forty-eight percent were female with a mean age 71 ± 18.6 years, 52% of whom were > 75. Mean CHA2DS2-Vasc and HAS-BLED scores were 4.1 ± 1.8 and 1.4 ± 0.8, respectively. Rivaroxaban, dabigatran and apixaban were prescribed to 154 (54.2%), 106 (34.3%) and 41 (13.2%) patients, respectively. 20.4% had inaccurate prescriptions; 92.9% (n = 65) underdosed and 7.1% (n = 5) on inappropriately higher doses. Neither choice of NOAC, age, history of anaemia, previous bleeding or co-prescribed antiplatelets influenced the accuracy of prescription (p = NS), but decreased renal function appeared to do so (p = 0.05). CONCLUSION: Our study highlights significant inaccuracies in NOAC prescribing. Patients commenced on NOACs should be assessed and followed up in a multidisciplinary AF clinic to ensure safe and effective prescribing and stroke prevention.

Dynamic changes of the composition of plasma HDL particles in patients with cardiac disease: Spotlight on sphingosine-1-phosphate/serum amyloid A ratio.

Several epidemiological studies reported an inverse relationship between plasma high-density lipoprotein (HDL) cholesterol levels and atherosclerotic cardiovascular disease (ASCVD). However, therapeutic interventions targeted at raising HDL-cholesterol failed to improve cardiovascular outcomes, suggesting that HDL components distinct from cholesterol may account for the anti-atherothrombotic effects attributed to this lipoprotein. Sphingosine-1-phosphate (S1P) and the acute phase protein serum amyloid A (SAA) have been identified as integral constituents of HDL particles. Evidence suggests that S1P and SAA levels within HDL particles may be affected by inflammation and oxidative stress, which are coexisting processes underlying ASCVD. Because SAA, an inflammation-related marker, and S1P, an anti-atherothrombotic marker, have relatively clear opposite characteristics among the HDL-associated proteins, the approach of assessing the two markers simultaneously may provide new insights in clinical practice (S1P/SAA Index). This review focuses on evidence in support of the concept that the S1P/SAA Index may affect the HDL atheroprotective properties and may, therefore represent a potential target for therapeutic interventions.

Time to redefine body mass index categories in chronic diseases? Spotlight on obesity paradox.

Obesity is a complex condition classically characterised by excessive body fat accumulation and represents one of the most important public health problems worldwide. Although several epidemiological studies have shown that elevated BMI is associated with higher morbidity, and with increased rate of death from all causes and from cardiovascular disease, accumulating evidence suggests that being overweight or obese may be protective (the so-called obesity paradox), at least in chronic diseases. These observations, not only question the validity of the BMI system, but also raise the intriguing question of whether we should redefine what the normal range of BMI is in individuals suffering from a chronic disease. In the present article, we review the available information on the association between elevated BMI and increased morbidity and mortality including obesity-related paradoxes, explore key aspects of the role and limitations of BMI as a measure of increased adiposity and outline potential solutions to address the current controversies regarding the impact of obesity on human health.

Erratum: New insights and new hope for pulmonary arterial hypertension: natriuretic peptides clearance receptor as a novel therapeutic target for a complex disease.

[This corrects the article on p. 112 in vol. 9, PMID: 28951773.].

New insights and new hope for pulmonary arterial hypertension: natriuretic peptides clearance receptor as a novel therapeutic target for a complex disease.

BACKGROUND: Pulmonary Arterial Hypertension (PAH) is a deadly and disabling disease for which there is no marketed drug that addresses the underlying disease mechanism and targets to cure patients. The lack of understanding of the disease mechanism represents the main challenges in developing curative therapies. We here report, for the first time, that mice lacking natriuretic peptides clearance receptor develop PAH. METHODS AND RESULTS: Initial studies assessed cardiac structure and function in NPR-C+/+ (wild type) and age matched, littermate NPR-C-/- mice by echocardiography. Mice lacking NPR-C had right atrial dilation, tricuspid regurgitation as well as echocardiographic signs of right ventricular pressure overload, including flattening and paradoxical bulging of the septum into the left ventricle during systole, and hypertrophy of the right ventricular free wall. Among the 10 NPR-C-/- mice aged between 12 and 20 weeks studied, 8 showed the above typical echocardiographic features of PAH [80%, 95% CI: (0.4439-0.9748)], and only one had pericardial effusion [10%, 95% CI: (0.0025-0.4450)], finding that has a prognostic significance in subjects affected by this clinical entity. To confirm the presence of increased right ventricular systolic pressure (RVSP) among NPR-C-/- mice, right heart catheterization was performed. Strikingly, RVSP was significantly elevated in NPR-C-/- mice compared to their age matched, littermate NPR-C+/+ mice, at baseline (21.95±0.56 mmHg vs. 5.3±0.6 mmHg, respectively (P<0.001)). CONCLUSION: The above results suggest that NPR-C-mediated signalling pathways play a critical role in the development of PAH, indicating that NPR-C is an important protective receptor in the heart rather than just being a clearance receptor.

Determination of Sphingosine-1-Phosphate in Human Plasma Using Liquid Chromatography Coupled with Q-Tof Mass Spectrometry.

Evidence suggests that high-density lipoprotein (HDL) components distinct from cholesterol, such as sphingosine-1-phosphate (S1P), may account for the anti-atherothrombotic effects attributed to this lipoprotein. The current method for the determination of plasma levels of S1P as well as levels associated with HDL particles is still cumbersome an assay method to be worldwide practical. Recently, a simplified protocol based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the sensitive and specific quantification of plasma levels of S1P with good accuracy has been reported. This work utilized a triple quadrupole (QqQ)-based LC-MS/MS system. Here we adapt that method for the determination of plasma levels of S1P using a quadrupole time of flight (Q-Tof) based LC-MS system. Calibration curves were linear in the range of 0.05 to 2 µM. The lower limit of quantification (LOQ) was 0.05 µM. The concentration of S1P in human plasma was determined to be 1 ± 0.09 µM (n = 6). The average accuracy over the stated range of the method was found to be 100 ± 5.9% with precision at the LOQ better than 10% when predicting the calibration standards. The concentration of plasma S1P in the prepared samples was stable for 24 h at room temperature. We have demonstrated the quantification of plasma S1P using Q-Tof based LC-MS with very good sensitivity, accuracy, and precision that can used for future studies in this field.

A natriuretic peptides clearance receptor's agonist reduces pulmonary artery pressures and enhances cardiac performance in preclinical models: New hope for patients with pulmonary hypertension due to left ventricular heart failure.

BACKGROUND: In patients with left ventricular heart failure (HF), the development of pulmonary hypertension (PH) is common and represents a strong predictor of death. Despite recent advances in the pathophysiological understanding there is as yet no prospect of cure of this deadly clinical entity and the majority of patients continue to progress to right ventricular failure and die. Furthermore, there is no single medical treatment currently approved for PH related to HF. There is, therefore an urgent unmet need to identify novel pharmacological agents that will prevent the progressive increased or reverse the elevated pulmonary arterial pressures while enhancing cardiac performance in HF. METHOD AND RESULTS: We here reported, for the first time, using a pressure-loop (P-V) conductance catheter system, that a specific natriuretic peptides clearance receptors' agonist, the ring-deleted atrial natriuretic peptide analogue, cANF4-23 (cANF) reduces pulmonary artery pressures. Strikingly, the administration of the cANF in these mice decreased the RVSP by 50% (n=5, F 25.687, DF 14, p<0.001) and heart rate (HR) by 11% (n=5, F 25.69, DF 14, p<0.001) as well as enhancing cardiac performance including left ventricular contractility in mice. Most strikingly, mice lacking NPR-C were much more susceptible to develop HF, indicating that NPR-C is a critical protective receptor in the heart. CONCLUSION: Natriuretic peptides clearance receptors' agonists may, therefore represent a novel and attractive therapeutic strategy for PH related to HF, and ultimately improves the life expectancy and quality for millions of people around the planet.

An update on the 2014 Ebola outbreak in Western Africa.

The recent Ebola outbreak in Western Africa was the most devastating outbreak witnessed in recent times. There have been remarkable local and international efforts to control the crisis. Ebola Virus Disease is the focus of immense research activity. The progression of events in the region has been evolving swiftly and it is of paramount importance to the medical community to be acquainted with the situation. Over 28000 people were inflicted with the condition, over 11000 have died. Novel data has emerged regarding modes of transmission, providing rationale for recent flare-ups. Similarly, studies on survivors are elucidating the later stages of the disease recovery process. Novel techniques for diagnosis are also discussed. Finally, the current research regarding treatment and vaccine development is reviewed, particularly the implementation of rVSV-ZEBOV vaccination programs.

Effect of sphingosine-1-phosphate on L-type calcium current and Ca(2+) transient in rat ventricular myocytes.

Modulation of Ca(2+) homoeostasis in cardiac myocytes plays a major role in beat-to-beat regulation of heart function. Previous studies suggest that sphingosine-1-phosphate (S1P), a biologically active sphingomyelin metabolite, regulates Ca(2+) handling in cardiac myocytes, but the underlying mechanism is unclear. In the present study, we tested the hypothesis that S1P-induced functional alteration of intracellular Ca(2+) handling includes the L-type calcium channel current (ICa,L) via a signalling pathway involving P21-activated kinase 1 (Pak1). Our results show that, in rat ventricular myocytes, S1P (100 nM) does not affect the basal activity of ICa,L but is able to partially reverse the effect of the ß-adrenergic agonist Isoproterenol (ISO, 100 nM) on ICa,L. S1P (25 nM) also significantly prevents ISO (5 nM)-induced Ca(2+) waves and diastolic Ca(2+) release in these cells. Our further molecular characterisation demonstrates that Pak1 activity is increased in myocytes treated with S1P (25 nM) compared with those myocytes without treatment of S1P. By immunoprecipitation we demonstrate that Pak1 and protein phosphatase 2A (PP2A) are associated in ventricular tissue indicating their functional interaction. Thus the results indicate that S1P attenuates ß-adrenergic stress-induced alteration of intracellular Ca(2+) release and L-type Ca(2+) channel current at least in part via Pak1-PP2A-mediated signalling.

Magnetic resonance myocardial perfusion imaging in the diagnosis of functionally significant obstructive coronary artery disease: a systematic review protocol.

BACKGROUND: Cardiac magnetic resonance (CMR) myocardial perfusion imaging has been suggested as a non-invasive alternative to pressure wire guided fractional flow reserve (FFR) in detecting haemodynamically significant obstructive coronary artery disease (CAD). The objective of this systematic review is to determine the diagnostic accuracy of CMR and to compare it to FFR. METHODS/DESIGN: A systematic review of diagnostic test accuracy of CMR and FFR will be conducted. Relevant English-language articles published before November 2013 in Medline, PubMed, EMBASE, Google scholar, Scopus and Cochrane databases will be identified. Relevant referenced articles from those selected will also be analysed. Articles describing diagnostic studies that compared CMR to FFR in patients with known or suspected coronary artery disease will be included. Two investigators will independently screen, assess quality and extract data from the selected articles. The Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool will be used to assess methodological quality. STATA 13 (the xtmelogit command) software will be used to calculate bivariate random effects models and estimate pooled sensitivity and specificity with 95% confidence intervals. Forests plots and summary receiver operating characteristics curves will also be generated. Sub-group pooled analyses using image quality of CMR (in terms of magnetic flux density - Tesla) and basis of analyses (coronary arterial territory vs. patients basis) at different FFR cutoffs (≤0.75 and ≤0.8) will also be performed. DISCUSSION: This systematic review will help to determine if CMR is an adequate alternative to FFR in the diagnosis of significant and obstructive CAD. We will also be able to assess diagnostic accuracy of specific types of CMR scan at different FFR cutoffs. SYSTEMATIC REVIEW REGISTRATION: This systematic review had been registered at PROSPERO and the registration number is CRD42013006180.