589 results found
Sau A, Mereu R, Taraborrelli P, et al., 2016, A long-term follow-up of patients with prolonged asystole of greater than 15 s on head-up tilt testing, INTERNATIONAL JOURNAL OF CARDIOLOGY, Vol: 203, Pages: 482-485, ISSN: 0167-5273
Howard JP, Shun-Shin MJ, Hartley A, et al., 2016, Quantifying the 3 Biases That Lead to Unintentional Overestimation of the Blood Pressure-Lowering Effect of Renal Denervation., Circulation: Cardiovascular Quality and Outcomes, Vol: 9, Pages: 14-22, ISSN: 1941-7713
BACKGROUND: Studies of renal denervation report disparate results. Meta-analysis by trial design may allow quantitative estimation of sources and magnitude of biases in denervation studies. METHODS AND RESULTS: One hundred forty nonrandomized, 6 randomized open-label, and 2 randomized blinded studies were analyzed for 2 outcomes: (1) blood pressure changes for nonrandomized, open-label randomized, and blinded studies; and (2) quantification of 3 biases potentially contributing to apparent antihypertensive effects: (a) regression to the mean, (b) asymmetrical data handling, and (c) true blood pressure drops caused by something other than the tested therapy (confounding). Nonrandomized studies and open-label randomized trials reported large reductions in office blood pressure of 23.6 mm Hg (95% confidence interval [CI], 22.0 to 25.3) and 29.1 mm Hg (95% CI, 25.2 to 33.1 mm Hg), respectively. They reported smaller reductions in ambulatory blood pressures (11.2 mm Hg; 95% CI, 10.0 to 12.4). The blinded trials found no significant reduction in blood pressure (2.9 mm Hg; 95% CI, -0.4 to 6.3). Analyses of these data indicate the magnitude of the 3 potential sources of bias to be regression to the mean, -1.01 mm Hg (95% CI, 4.24 to -6.27); asymmetrical data handling, -10.8 mm Hg (95% CI, -8.77 to -12.87); and confounding, -8.3 mm Hg (95% CI, -4.73 to -11.83). CONCLUSIONS: Increasingly bias-resistant trial designs report effect sizes of decreasing magnitude. This disparity may be caused by asymmetrical data handling and confounding (eg, increased drug adherence). If these differences are caused by trial design and not by some other differences in patients or procedures, which happen to match the trial design, then randomization alone is not enough: blinding is also needed. This has broad implications across trials of medications and devices.
Petraco R, Sen S, Nijjer S, et al., 2015, ECG-Independent Calculation of Instantaneous Wave-Free Ratio, JACC-CARDIOVASCULAR INTERVENTIONS, Vol: 8, Pages: 2043-2046, ISSN: 1936-8798
Howard JP, Patel H, Shun-Shin MJ, et al., 2015, Impact of number of prescribed medications on visit-to-visit variability of blood pressure: implications for design of future trials of renal denervation, JOURNAL OF HYPERTENSION, Vol: 33, Pages: 2359-2367, ISSN: 0263-6352
Sohaib SMA, Wright I, Lim E, et al., 2015, Atrioventricular Optimized Direct His Bundle Pacing Improves Acute Hemodynamic Function in Patients With Heart Failure and PR Interval Prolongation Without Left Bundle Branch Block, JACC: Clinical electrophysiology, Vol: 1, Pages: 582-591, ISSN: 2405-5018
ObjectivesThe purpose of this study was to investigate whether heart failure patients with narrow QRS duration (or right bundle branch block) but with long PR interval gain acute hemodynamic benefit from atrioventricular (AV) optimization. We tested this with biventricular pacing and (to deliver pure AV shortening) direct His bundle pacing.BackgroundBenefits of pacing for heart failure have previously been indicated by acute hemodynamic studies and verified in outcome studies. A new target for pacing in heart failure may be PR interval prolongation, which is associated with 58% higher mortality regardless of QRS duration.MethodsWe enrolled 16 consecutive patients with systolic heart failure, PR interval prolongation (mean, 254 ± 62 ms) and narrow QRS duration (n = 13; mean QRS duration: 119 ± 17 ms) or right bundle branch block (n = 3; mean, QRS duration: 156 ± 18 ms). We successfully delivered temporary direct His bundle pacing in 14 patients and temporary biventricular pacing in 14 participants. We performed AV optimization using invasive systolic blood pressure obtaining parabolic responses (mean R2: 0.90 for His, and 0.85 for biventricular pacing).ResultsThe mean increment in systolic BP compared with intrinsic ventricular conduction was 4.1 mm Hg (95% confidence interval [CI]: +1.9 to +6.2 mm Hg for His and 4.3 mm Hg [95% CI: +2.0 to +6.5 mm Hg] for biventricular pacing. QRS duration lengthened with biventricular pacing (change = +22 ms [95% CI: +18 to +25 ms]) but not with His pacing (change = +0.5 ms [95% CI: −2.6 to +3.6 ms).ConclusionsAV-optimized pacing improves acute hemodynamic function in patients with heart failure and long PR interval without left bundle branch block. That it can be achieved by single-site His pacing shows that its mechanism is AV shortening. The improvement is ∼60% of the effect size previously reported for biventricular pacing in left bundle branch block. Randomized, blinded trials are warranted to tes
Maznyczka A, Sen S, Cook C, et al., 2015, The ischaemic constellation: an alternative to the ischaemic cascade - implications for the validation of new ischaemic tests, OPEN HEART, Vol: 2, ISSN: 2053-3624
Finegold JA, Francis DP, 2015, What proportion of symptomatic side-effects in patients taking statins are genuinely caused by the drug? A response to letters., Eur J Prev Cardiol, Vol: 22, Pages: 1328-1330
Baksi AJ, Davies JE, Hadjiloizou N, et al., 2015, Attenuation of reflected waves in man during retrograde propagation from femoral artery to proximal aorta, International Journal of Cardiology, Vol: 202, Pages: 441-445, ISSN: 1874-1754
BackgroundWave reflection may be an important influence on blood pressure, but the extent to which reflections undergo attenuation during retrograde propagation has not been studied. We quantified retrograde transmission of a reflected wave created by occlusion of the left femoral artery in man.Methods20 subjects (age 31–83 years; 14 male) underwent invasive measurement of pressure and flow velocity with a sensor-tipped intra-arterial wire at multiple locations distal to the proximal aorta before, during and following occlusion of the left femoral artery by thigh cuff inflation. A numerical model of the circulation was also used to predict reflected wave transmission. Wave reflection was measured as the ratio of backward to forward wave energy (WRI) and the ratio of peak backward to forward pressure (Pb/Pf).ResultsCuff inflation caused a marked reflection which was largest at 5–10 cm from the cuff (change (Δ) in WRI = 0.50 (95% CI 0.38, 0.62); p < 0.001, ΔPb/Pf = 0.23 (0.18–0.29); p < 0.001). The magnitude of the cuff-induced reflection decreased progressively at more proximal locations and was barely discernible at sites > 40 cm from the cuff including in the proximal aorta. Numerical modelling gave similar predictions to those observed experimentally.ConclusionsReflections due to femoral artery occlusion are markedly attenuated by the time they reach the proximal aorta. This is due to impedance mismatches of bifurcations traversed in the backward direction. This degree of attenuation is inconsistent with the idea of a large discrete reflected wave arising from the lower limb and propagating back into the aorta.
Cole GD, Nowbar A, Mielewczik M, et al., 2015, Frequency of discrepancies in retracted clinical trial reports versus unretracted reports: blinded case-control study, British Medical Journal, Vol: 351, ISSN: 1468-5833
Objectives To compare the frequency of discrepancies in retracted reports of clinical trials with those in adjacent unretracted reports in the same journal.Design Blinded case-control study.Setting Journals in PubMed.Population 50 manuscripts, classified on PubMed as retracted clinical trials, paired with 50 adjacent unretracted manuscripts from the same journals. Reports were randomly selected from PubMed in December 2012, with no restriction on publication date. Controls were the preceding unretracted clinical trial published in the same journal. All traces of retraction were removed. Three scientists, blinded to the retraction status of individual reports, reviewed all 100 trial reports for discrepancies. Discrepancies were pooled and cross checked before being counted into prespecified categories. Only then was the retraction status unblinded for analysis.Main outcome measure Total number of discrepancies (defined as mathematically or logically contradictory statements) in each clinical trial report.Results Of 479 discrepancies found in the 100 trial reports, 348 were in the 50 retracted reports and 131 in the 50 unretracted reports. On average, individual retracted reports had a greater number of discrepancies than unretracted reports (median 4 (interquartile range 2-8.75) v 0 (0-5); P<0.001). Papers with a discrepancy were significantly more likely to be retracted than those without a discrepancy (odds ratio 5.7 (95% confidence interval 2.2 to 14.5); P<0.001). In particular, three types of discrepancy arose significantly more frequently in retracted than unretracted reports: factual discrepancies (P=0.002), arithmetical errors (P=0.01), and missed P values (P=0.02). Results from a retrospective analysis indicated that citations and journal impact factor were unlikely to affect the result.Conclusions Discrepancies in published trial reports should no longer be assumed to be unimportant. Scientists, blinded to retraction status and with no specialist skill
Ahmad Y, Nijjer S, Cook CM, et al., 2015, A new method of applying randomised control study data to the individual patient: A novel quantitative patient-centred approach to interpreting composite end points, INTERNATIONAL JOURNAL OF CARDIOLOGY, Vol: 195, Pages: 216-224, ISSN: 0167-5273
Dehbi H-M, Jones S, Sohaib SMA, et al., 2015, A novel curve fitting method for AV optimisation of biventricular pacemakers, PHYSIOLOGICAL MEASUREMENT, Vol: 36, Pages: 1889-1900, ISSN: 0967-3334
Cole GD, Francis DP, 2015, Trials are best, ignore the rest: safety and efficacy of digoxin., BMJ, Vol: 351
Koa-Wing M, Nakagawa H, Luther V, et al., 2015, A diagnostic algorithm to optimize data collection and interpretation of Ripple Maps in atrial tachycardias, International Journal of Cardiology, Vol: 199, Pages: 391-400, ISSN: 1874-1754
BackgroundRipple Mapping (RM) is designed to overcome the limitations of existing isochronal 3D mapping systems by representing the intracardiac electrogram as a dynamic bar on a surface bipolar voltage map that changes in height according to the electrogram voltage–time relationship, relative to a fiduciary point.ObjectiveWe tested the hypothesis that standard approaches to atrial tachycardia CARTO™ activation maps were inadequate for RM creation and interpretation. From the results, we aimed to develop an algorithm to optimize RMs for future prospective testing on a clinical RM platform.MethodsCARTO-XP™ activation maps from atrial tachycardia ablations were reviewed by two blinded assessors on an off-line RM workstation. Ripple Maps were graded according to a diagnostic confidence scale (Grade I — high confidence with clear pattern of activation through to Grade IV — non-diagnostic). The RM-based diagnoses were corroborated against the clinical diagnoses.Results43 RMs from 14 patients were classified as Grade I (5 [11.5%]); Grade II (17 [39.5%]); Grade III (9 [21%]) and Grade IV (12 [28%]). Causes of low gradings/errors included the following: insufficient chamber point density; window-of-interest < 100% of cycle length (CL); < 95% tachycardia CL mapped; variability of CL and/or unstable fiducial reference marker; and suboptimal bar height and scar settings.ConclusionsA data collection and map interpretation algorithm has been developed to optimize Ripple Maps in atrial tachycardias. This algorithm requires prospective testing on a real-time clinical platform.
Raphael CE, Finegold JA, Barron AJ, et al., 2015, The effect of duration of follow-up and presence of competing risk on lifespan-gain from implantable cardioverter defibrillator therapy: who benefits the most?, EUROPEAN HEART JOURNAL, Vol: 36, Pages: 1676-1688, ISSN: 0195-668X
Cole GD, Dhutia NM, Shun-Shin MJ, et al., 2015, Defining the real-world reproducibility of visual grading and visual estimation of left ventricular ejection fraction: impact of image quality, experience and accreditation., International Journal of Cardiovascular Imaging, Vol: 31, Pages: 1303-1314, ISSN: 1569-5794
Left ventricular function can be evaluated by qualitative grading and by eyeball estimation of ejection fraction (EF). We sought to define the reproducibility of these techniques, and how they are affected by image quality, experience and accreditation. Twenty apical four-chamber echocardiographic cine loops (Online Resource 1–20) of varying image quality and left ventricular function were anonymized and presented to 35 operators. Operators were asked to provide (1) a one-phrase grading of global systolic function (2) an “eyeball” EF estimate and (3) an image quality rating on a 0–100 visual analogue scale. Each observer viewed every loop twice unknowingly, a total of 1400 viewings. When grading LV function into five categories, an operator’s chance of agreement with another operator was 50 % and with themself on blinded re-presentation was 68 %. Blinded eyeball LVEF re-estimates by the same operator had standard deviation (SD) of difference of 7.6 EF units, with the SD across operators averaging 8.3 EF units. Image quality, defined as the average of all operators’ assessments, correlated with EF estimate variability (r = −0.616, p < 0.01) and visual grading agreement (r = 0.58, p < 0.01). However, operators’ own single quality assessments were not a useful forewarning of their estimate being an outlier, partly because individual quality assessments had poor within-operator reproducibility (SD of difference 17.8). Reproducibility of visual grading of LV function and LVEF estimation is dependent on image quality, but individuals cannot themselves identify when poor image quality is disrupting their LV function estimate. Clinicians should not assume that patients changing in grade or in visually estimated EF have had a genuine clinical change.
Cole GD, Shun-Shin MJ, Nowbar AN, et al., 2015, Difficulty in detecting discrepancies in a clinical trial report:260-reader evaluation, International Journal of Epidemiology, Vol: 44, Pages: 862-869, ISSN: 1464-3685
Background: Scientific literature can contain errors. Discrepancies, defined as two or more statements or results that cannot both be true, may be a signal of problems with a trial report. In this study, we report how many discrepancies are detected by a large panel of readers examining a trial report containing a large number of discrepancies.Methods: We approached a convenience sample of 343 journal readers in seven countries, and invited them in person to participate in a study. They were asked to examine the tables and figures of one published article for discrepancies. 260 participants agreed, ranging from medical students to professors. The discrepancies they identified were tabulated and counted. There were 39 different discrepancies identified. We evaluated the probability of discrepancy identification, and whether more time spent or greater participant experience as academic authors improved the ability to detect discrepancies.Results: Overall, 95.3% of discrepancies were missed. Most participants (62%) were unable to find any discrepancies. Only 11.5% noticed more than 10% of the discrepancies. More discrepancies were noted by participants who spent more time on the task (Spearman’s ρ = 0.22, P < 0.01), and those with more experience of publishing papers (Spearman’s ρ = 0.13 with number of publications, P = 0.04).Conclusions: Noticing discrepancies is difficult. Most readers miss most discrepancies even when asked specifically to look for them. The probability of a discrepancy evading an individual sensitized reader is 95%, making it important that, when problems are identified after publication, readers are able to communicate with each other. When made aware of discrepancies, the majority of readers support editorial action to correct the scientific record.
Barron AJ, Dhutia NM, Glaeser S, et al., 2015, Physiology of oxygen uptake kinetics: Insights from incremental cardiopulmonary exercise testing in the Study of Health in Pomerania, IJC METABOLIC & ENDOCRINE, Vol: 7, Pages: 3-9, ISSN: 2214-7624
Ahmad Y, Sen S, Shun-Shin MJ, et al., 2015, Intra-aortic Balloon Pump Therapy for Acute Myocardial Infarction AMeta-analysis, JAMA INTERNAL MEDICINE, Vol: 175, Pages: 931-939, ISSN: 2168-6106
Nijjer SS, Petraco R, van de Hoef TP, et al., 2015, Change in Coronary Blood Flow After Percutaneous Coronary Intervention in Relation to Baseline Lesion Physiology Results of the JUSTIFY-PCI Study, CIRCULATION-CARDIOVASCULAR INTERVENTIONS, Vol: 8, ISSN: 1941-7640
Sohaib SM, Kyriacou A, Jones S, et al., 2015, Evidence that conflict regarding size of haemodynamic response to interventricular delay optimization of cardiac resynchronization therapy may arise from differences in how atrioventricular delay is kept constant., Europace, Vol: 17, ISSN: 1532-2092
AIMS: Whether adjusting interventricular (VV) delay changes haemodynamic efficacy of cardiac resynchronization therapy (CRT) is controversial, with conflicting results. This study addresses whether the convention for keeping atrioventricular (AV) delay constant during VV optimization might explain these conflicts. METHOD AND RESULTS: Twenty-two patients in sinus rhythm with existing CRT underwent VV optimization using non-invasive systolic blood pressure. Interventricular optimization was performed with four methods for keeping the AV delay constant: (i) atrium and left ventricle delay kept constant, (ii) atrium and right ventricle delay kept constant, (iii) time to the first-activated ventricle kept constant, and (iv) time to the second-activated ventricle kept constant. In 11 patients this was performed with AV delay of 120 ms, and in 11 at AV optimum. At AV 120 ms, time to the first ventricular lead (left or right) was the overwhelming determinant of haemodynamics (13.75 mmHg at ±80 ms, P < 0.001) with no significant effect of time to second lead (0.47 mmHg, P = 0.50), P < 0.001 for difference. At AV optimum, time to first ventricular lead again had a larger effect (5.03 mmHg, P < 0.001) than time to second (2.92 mmHg, P = 0.001), P = 0.02 for difference. CONCLUSION: Time to first ventricular activation is the overwhelming determinant of circulatory function, regardless of whether this is the left or right ventricular lead. If this is kept constant, the effect of changing time to the second ventricle is small or nil, and is not beneficial. In practice, it may be advisable to leave VV delay at zero. Specifying how AV delay is kept fixed might make future VV delay research more enlightening.
Sohaib SMA, Finegold JA, Nijjer SS, et al., 2015, Opportunity to Increase Life Span in Narrow QRS Cardiac Resynchronization Therapy Recipients by Deactivating Ventricular Pacing Evidence From Randomized Controlled Trials, JACC-HEART FAILURE, Vol: 3, Pages: 327-336, ISSN: 2213-1779
Nijjer SS, Sen S, Petraco R, et al., 2015, The Instantaneous wave-Free Ratio (iFR) pullback: a novel innovation using baseline physiology to optimise coronary angioplasty in tandem lesions, CARDIOVASCULAR REVASCULARIZATION MEDICINE, Vol: 16, Pages: 167-171, ISSN: 1553-8389
Ploux S, Eschalier R, Whinnett ZI, et al., 2015, Electrical dyssynchrony induced by biventricular pacing: Implications for patient selection and therapy improvement, HEART RHYTHM, Vol: 12, Pages: 782-791, ISSN: 1547-5271
Jamil-Copley S, Vergara P, Carbucicchio C, et al., 2015, Application of Ripple Mapping to Visualize Slow Conduction Channels Within the Infarct-Related Left Ventricular Scar, CIRCULATION-ARRHYTHMIA AND ELECTROPHYSIOLOGY, Vol: 8, Pages: 76-U110, ISSN: 1941-3149
Finegold J, Bordachar P, Kyriacou A, et al., 2015, Atrioventricular delay optimization of cardiac resynchronisation therapy: Comparison of non-invasive blood pressure with invasive haemodynamic measures, INTERNATIONAL JOURNAL OF CARDIOLOGY, Vol: 180, Pages: 221-222, ISSN: 0167-5273
Howard JP, Francis DP, 2015, Overcoming the three biases obscuring the science of renal denervation in humans: Big-day bias, check-once-more bias and I-will-take-it-now bias, TRENDS IN CARDIOVASCULAR MEDICINE, Vol: 25, Pages: 116-118, ISSN: 1050-1738
Cole GD, Shun-Shin MJ, Finegold JA, et al., 2015, Grateful receipt of clarifications on a perioperative trial: An illustration of the duty of readers to ask questions, INTERNATIONAL JOURNAL OF CARDIOLOGY, Vol: 179, Pages: 507-509, ISSN: 0167-5273
Jabbour RJ, Shun-Shin MJ, Finegold JA, et al., 2015, Effect of Study Design on the Reported Effect of Cardiac Resynchronization Therapy (CRT) on Quantitative Physiological Measures: Stratified Meta-Analysis in Narrow-QRS Heart Failure and Implications for Planning Future Studies, JOURNAL OF THE AMERICAN HEART ASSOCIATION, Vol: 4, ISSN: 2047-9980
Panikker S, Virmani R, Sakakura K, et al., 2015, Left atrial appendage electrical isolation and concomitant device occlusion: A safety and feasibility study with histologic characterization, HEART RHYTHM, Vol: 12, Pages: 202-210, ISSN: 1547-5271
Howard JP, Shun-Shin MJ, Francis DP, 2015, Great myths of blood pressure effect size in renal denervation, Renal Denervation: A New Approach to Treatment of Resistant Hypertension, Pages: 175-180, ISBN: 9781447152224
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