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Dive into the research topics where Muhammad A. Khan is active.

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Featured researches published by Muhammad A. Khan.


International Journal of Cardiology | 2014

Bariatric surgery and its impact on cardiovascular disease and mortality: a systematic review and meta-analysis.

Chun Shing Kwok; Ashish Pradhan; Muhammad A. Khan; Simon G. Anderson; Bernard Keavney; Phyo K. Myint; Mamas A. Mamas; Yoon K. Loke

BACKGROUND Bariatric surgery has been shown to improve cardiovascular risk factors but long term benefits for survival and cardiovascular events are still uncertain. METHODS We searched MEDLINE and EMBASE for parallel group studies that evaluated the clinical outcomes associated with bariatric surgery as compared to non-surgical treatment. Relevant studies were pooled using random effects meta-analysis for risk of myocardial infarction, stroke, cardiovascular events and mortality. RESULTS 14 studies met the inclusion criteria, which included 29,208 patients who underwent bariatric surgery and 166,200 nonsurgical controls (mean age 48 years, 30% male, follow up period ranged from 2 years to 14.7 years). Four studies were considered at moderate-high risk of bias, whilst ten studies were at moderate or lower risk of bias. Compared to nonsurgical controls there was more than 50% reduction in mortality amongst patients who had bariatric surgery (OR 0.48 95% CI 0.35-0.64, I2=86%, 14 studies). In pooled analysis of four studies with adjusted data, bariatric surgery was associated with a significantly reduced risk of composite cardiovascular adverse events (OR 0.54 95% CI 0.41-0.70, I2=58%). Bariatric surgery was also associated with significant reduction in specific endpoints of myocardial infarction (OR 0.46 95% CI 0.30-0.69, I2=79%, 4 studies) and stroke (OR 0.49 95% CI 0.32-0.75, I2=59%, 4 studies). CONCLUSIONS Data from observational studies indicates that patients undergoing bariatric surgery have a reduced risk of myocardial infarction, stroke, cardiovascular events and mortality compared to non-surgical controls. Future randomized studies should investigate whether these observations are reproduced in a clinical trials setting.


Circulation-cardiovascular Interventions | 2015

Access and Non–Access Site Bleeding After Percutaneous Coronary Intervention and Risk of Subsequent Mortality and Major Adverse Cardiovascular Events Systematic Review and Meta-Analysis

Chun Shing Kwok; Muhammad A. Khan; Sunil V. Rao; Tim Kinnaird; Matthew Sperrin; Iain Buchan; Mark A. de Belder; Peter Ludman; James Nolan; Yoon K. Loke; Mamas A. Mamas

Background—The prognostic impact of site-specific major bleeding complications after percutaneous coronary intervention (PCI) has yielded conflicting data. The aim of this study is to provide an overview of site-specific major bleeding events in contemporary PCI and study their impact on mortality and major adverse cardiovascular event outcomes. Methods and Results—We conducted a meta-analysis of PCI studies that evaluated site-specific periprocedural bleeding complications and their impact on major adverse cardiovascular events and mortality outcomes. A systematic search of MEDLINE and Embase was conducted to identify relevant studies and random effects meta-analysis was used to estimate the risk of adverse outcomes with site-specific bleeding complications. Twenty-five relevant studies including 2 400 645 patients that underwent PCI were identified. Both non–access site (risk ratio [RR], 4.06; 95% confidence interval [CI], 3.21–5.14) and access site (RR, 1.71; 95% CI, 1.37–2.13) related bleeding complications were independently associated with an increased risk of periprocedural mortality. The prognostic impact of non–access site–related bleeding events on mortality related to the source of anatomic bleeding, for example, gastrointestinal RR, 2.78; 95% CI, 1.25 to 6.18; retroperitoneal RR, 5.87; 95% CI, 1.63 to 21.12; and intracranial RR, 22.71; 95% CI, 12.53 to 41.15. Conclusions—The prognostic impact of bleeding complications after PCI varies according to anatomic source and severity. Non–access site-related bleeding complications have a similar prevalence to those from the access site but are associated with a significantly worse prognosis partly related to the severity of the bleed. Clinicians should minimize the risk of major bleeding complications during PCI through judicious use of bleeding avoidance strategies irrespective of the access site used.


Catheterization and Cardiovascular Interventions | 2014

Stent fracture: Insights on mechanisms, treatments, and outcomes from the food and drug administration manufacturer and user facility device experience database

Mamas A. Mamas; Nicolas Foin; Chad Abunassar; Muhammad A. Khan; Carlo Di Mario; Douglas G. Fraser

Stent fracture (SF) is an uncommon complication following percutaneous coronary intervention. Previous studies of SF have either been small single‐center studies or have reported data mainly from first generation platforms. The FDA MAUDE database was used to identify cases of SF to gain mechanistic insight into procedural and anatomical factors predisposing to this complication, to define treatment and associated clinical outcomes in contemporary and first generation stent platforms.


World Journal of Cardiology | 2013

Atrial fibrillation in heart failure: The sword of Damocles revisited

Muhammad A. Khan; Fozia Zahir Ahmed; Ludwig Neyses; Mamas A. Mamas

Heart failure (HF) and atrial fibrillation (AF) frequently coexist and have emerged as major cardiovascular epidemics. There is growing evidence that AF is an independent prognostic marker in HF and affects patients with both reduced as well as preserved LV systolic function. There has been a general move in clinical practice from a rhythm control to a rate control strategy in HF patients with AF, although recent data suggests that rhythm control strategies may provide better outcomes in selected subgroups of HF patients. Furthermore, various therapeutic modalities including pace and ablate strategies with cardiac resynchronisation or radiofrequency ablation have become increasingly adopted, although their role in the management of AF in patients with HF remains uncertain. This article presents an overview of the multidimensional impact of AF in patients with HF. Relevant literature is highlighted and the effect of various therapeutic modalities on prognosis is discussed. Finally, while novel anticoagulants usher in a new era in thromboprophylaxis, research continues in a variety of new pathways including selective atrial anti-arrhythmic agents and genomic polymorphisms in AF with HF.


Proceedings of the Institution of Mechanical Engineers - Part J: Journal of Engineering Tribology. 2008;. | 2008

A methodology for online wear debris morphology and composition analysis

Muhammad A. Khan; Andrew Starr; Dennis Cooper

Online or inline detection of basic debris features, i.e. size, quantity, size distribution, shape, and compositions simultaneously with real time diagnostics is one of the possible ways to perform wear debris analysis with high reliability. At present many techniques and sensors are available that can perform near real time detection and diagnostics for debris quantitative features. But to perform real time detection and diagnostics for features like shape and composition still requires a reliable technical concept. In this article a new technique for online wear debris shape and composition analysis is described. The developed technique is a combination of hardware and software based on imaging technology for shape and composition detection. Rule-based algorithms are used to perform near real time debris analysis diagnostics. An experimental study is also presented that shows the possible potential of the developed technique on real applications.


Circulation-cardiovascular Interventions | 2017

Closure of Secundum Atrial Septal Defects With the AMPLATZER Septal Occluder: A Prospective, Multicenter, Post-Approval Study

Daniel R. Turner; Carl Y. Owada; Charlie J. Sang; Muhammad A. Khan; D. Scott Lim

Background— Prospective data on the medium-term safety and effectiveness of the AMPLATZER Septal Occluder in clinical practice are not available. The objective of this study was to prospectively evaluate the risk of hemodynamic compromise and obtain medium-term survival data on patients implanted with the AMPLATZER Septal Occluder for percutaneous closure of secundum atrial septal defects. Methods and Results— Subjects were enrolled prospectively at 50 US sites and followed for 2 years. Between 2008 and 2012, atrial septal defect closure with the AMPLATZER Septal Occluder was attempted in 1000 patients (aged 0.3–83.6 years, mean 21±22 years). Procedural closure occurred in 97.9%, with 1-month and 2-year closure 98.5% and 97.9%, respectively. Hemodynamic compromise occurred in 6 subjects (0.65%), because of dysrhythmia in 2, device embolization in 1, and cardiac erosion in 3. The rate of cardiac erosion was 0.3% (average 83, range 12–171 days from implant). Conclusions— Closure of atrial septal defect with the AMPLATZER Septal Occluder is safe and effective. The rate of hemodynamic compromise and cardiac erosion is rare. The risk factors for cardiac erosion after device closure are not yet clear. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00650936.


Cardiology in The Young | 2015

Percutaneous removal of right atrial thrombus by suction technique

Muhammad A. Khan; Tarek S. Momenah

We present a case of percutaneous removal of a large right atrial thrombus formed after insertion of a ventriculoatrial shunt for hydrocephalus.


Current Cardiology Reviews | 2012

Atrial Fibrillation in Heart Failure: An Innocent Bystander?

Muhammad A. Khan; Ludwig Neyses; Mamas A. Mamas

Heart failure (HF) and atrial fibrillation (AF) frequently coexist and each complicates the course of the other. The purpose of this review is to analyse the prognostic impact of AF in patients with HF and assess whether there is an advantage in targeting therapies towards the maintenance of sinus rhythm (SR) in this cohort of patients. The presence of AF in patients with HF has been reported to be independently associated with an increase in mortality in many studies and this increased risk is observed in those with both preserved and impaired LV systolic function. The optimal strategy for targeting AF in patients with HF is unclear but recent randomised controlled studies indicate no significant prognostic advantage associated with a rhythm control strategy as compared to a rate control strategy. A number of small studies have investigated the role of both cardiac resynchronization therapy (CRT) and AF catheter ablation for the maintenance of / conversion to SR in patients with HF with initial promising results although larger randomised controlled studies will need to be performed to define the role of these modalities in the treatment of this cohort and whether preliminary benefits observed in these studies translate to improvements in longer term prognosis. Finally, there has been a focus on modifying the arrythmogenic atrial substrate and neurohormonal milieu by pharmacological means in order to prevent AF although it remains to be seen whether this approach proves to be efficacious with improvements in clinically relevant outcomes.


Catheterization and Cardiovascular Interventions | 2015

Acquired aortic atresia: Catheter therapy using covered stents.

Tarek Sulaiman Momenah; Muhammad A. Khan; Shakeel A. Qureshi; Ziyad M. Hijazi

To maintain aortic continuity, aortic arch interruption is usually treated surgically. We present our experience of aortic arch reconstruction using percutaneous implantation of covered stents and mid‐term follow‐up.


Cardiology in The Young | 2015

Alpha blocker and angiotensin-converting enzyme inhibitor in the management of severe pulmonary valve stenosis: from bench to bedside.

Mohammed Omar Galal; Muhammad A. Khan

INTRODUCTION Neonates with severe pulmonary valve stenosis tend to remain oxygen dependent, despite resolution of the transpulmonary gradient. Alpha 2 blockers – phentolamine – and angiotensin-converting enzyme inhibitors – captopril – were reported to improve oxygen saturation. OBJECTIVE To describe the role of phentolamine and captopril in the treatment of these patients. METHODS In a retrospective cohort study, 28 neonates with severe pulmonary valve stenosis underwent balloon valvuloplasty. Among them, 20 remained oxygen or prostaglandin dependent after intervention, and were treated with phentolamine or captopril. Oxygen saturation was monitored before and after intervention and following treatment with these medications. Mean duration of hospitalisation was recorded. RESULTS Mean age and weight were 25.2 days and 3.1 kg, respectively. Before balloon dilation, 18/20 (90%) neonates were on prostaglandin, whereas after the procedure only 6/18 patients required it. All 20 patients required oxygen after the procedure, and nine patients (45%) were started on phentolamine. Among them, one patient with severe infundibular stenosis did not respond favourably, and 11 patients (55%) were started on captopril. After starting phentolamine or captopril treatment, prostaglandin could be discontinued after a mean time of 15.86 hours. Within <2 days, there was an increase in mean oxygen saturation from 76.6 to 93.0%. CONCLUSION Phentolamine and captopril seem to have therapeutic roles in neonates with severe pulmonary valve stenosis who remain oxygen dependent after balloon dilation. Both drugs led to vasodilation of the pulmonary and systemic vascularisation and facilitated inflow to the right ventricle. Right-to-left shunt across a patent foramen ovale or atrial septal defect decreased and saturation improved, leading to a significant reduction in the length of hospitalisation.

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Dennis Cooper

University of Manchester

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Yoon K. Loke

University of East Anglia

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Ludwig Neyses

University of Luxembourg

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