Auricchio A, Lumens J, Prinzen FW Does cardiac resynchronization therapy benefit patients with right bundle branch block: cardiac resynchronization therapy has a role in patients with right bundle branch block. Circ Arrhythm Electrophysiol. 2014 Jun;7(3):532-42. doi: 10.1161/CIRCEP.113.000628. Review.
Fang F, Chan JY, Yip GW, Xie JM, Zhang Q, Fung JW, Lam YY, Yu CM Prevalence and determinants of left ventricular systolic dyssynchrony in patients with normal ejection fraction received right ventricular apical pacing: a real-time three-dimensional echocardiographic study. Eur J Echocardiogr. 2010 Mar;11(2):109-18. doi: 10.1093/ejechocard/jep171. Epub 2009 Nov 20.
Fang F, Zhang Q, Chan JY, Razali O, Azlan H, Chan HC, Sanderson JE, Xie JM, Yu CM Early pacing-induced systolic dyssynchrony is a strong predictor of left ventricular adverse remodeling: analysis from the Pacing to Avoid Cardiac Enlargement (PACE) trial. Int J Cardiol. 2013 Sep 30;168(2):723-8. doi: 10.1016/j.ijcard.2012.08.005. Epub 2012 Sep 1.
Fung JW, Chan JY, Yip GW, Chan HC, Chan WW, Zhang Q, Yu CM Effect of left ventricular endocardial activation pattern on echocardiographic and clinical response to cardiac resynchronization therapy. Heart. 2007 Apr;93(4):432-7. Epub 2007 Jan 19.
Fung JW, Lam YY, Zhang Q, Yip GW, Chan WW, Chan GC, Chan JY, Yu CM Effect of left ventricular lead concordance to the delayed contraction segment on echocardiographic and clinical outcomes after cardiac resynchronization therapy. J Cardiovasc Electrophysiol. 2009 May;20(5):530-5. doi: 10.1111/j.1540-8167.2008.01364.x. Epub 2008 Nov 21.
Fung JW, Zhang Q, Yip GW, Chan JY, Chan HC, Yu CM Effect of cardiac resynchronization therapy in patients with moderate left ventricular systolic dysfunction and wide QRS complex: a prospective study. J Cardiovasc Electrophysiol. 2006 Dec;17(12):1288-92. Epub 2006 Sep 20.
Ghosh S, Silva JN, Canham RM, Bowman TM, Zhang J, Rhee EK, Woodard PK, Rudy Y Electrophysiologic substrate and intraventricular left ventricular dyssynchrony in nonischemic heart failure patients undergoing cardiac resynchronization therapy. Heart Rhythm. 2011 May;8(5):692-9. doi: 10.1016/j.hrthm.2011.01.017. Epub 2011 Jan 11.
Gold MR, Thébault C, Linde C, Abraham WT, Gerritse B, Ghio S, St John Sutton M, Daubert JC Effect of QRS duration and morphology on cardiac resynchronization therapy outcomes in mild heart failure: results from the Resynchronization Reverses Remodeling in Systolic Left Ventricular Dysfunction (REVERSE) study. Circulation. 2012 Aug 14;126(7):822-9. doi: 10.1161/CIRCULATIONAHA.112.097709. Epub 2012 Jul 10.
Haghjoo M, Bagherzadeh A, Farahani MM, Haghighi ZO, Sadr-Ameli MA Significance of QRS morphology in determining the prevalence of mechanical dyssynchrony in heart failure patients eligible for cardiac resynchronization: particular focus on patients with right bundle branch block with and without coexistent left-sided conduction defects. Europace. 2008 May;10(5):566-71. doi: 10.1093/europace/eun081. Epub 2008 Apr 3.
Lund LH, Jurga J, Edner M, Benson L, Dahlström U, Linde C, Alehagen U Prevalence, correlates, and prognostic significance of QRS prolongation in heart failure with reduced and preserved ejection fraction. Eur Heart J. 2013 Feb;34(7):529-39. doi: 10.1093/eurheartj/ehs305. Epub 2012 Oct 4.
Nery PB, Ha AC, Keren A, Birnie DH Cardiac resynchronization therapy in patients with left ventricular systolic dysfunction and right bundle branch block: a systematic review. Heart Rhythm. 2011 Jul;8(7):1083-7. doi: 10.1016/j.hrthm.2011.01.041. Epub 2011 Feb 4. Review.
Russo AM, Stainback RF, Bailey SR, Epstein AE, Heidenreich PA, Jessup M, Kapa S, Kremers MS, Lindsay BD, Stevenson LW ACCF/HRS/AHA/ASE/HFSA/SCAI/SCCT/SCMR 2013 appropriate use criteria for implantable cardioverter-defibrillators and cardiac resynchronization therapy: a report of the American College of Cardiology Foundation appropriate use criteria task force, Heart Rhythm Society, American Heart Association, American Society of Echocardiography, Heart Failure Society of America, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, and Society for Cardiovascular Magnetic Resonance. J Am Coll Cardiol. 2013 Mar 26;61(12):1318-68. doi: 10.1016/j.jacc.2012.12.017. Epub 2013 Mar 1.
Sipahi I, Chou JC, Hyden M, Rowland DY, Simon DI, Fang JC Effect of QRS morphology on clinical event reduction with cardiac resynchronization therapy: meta-analysis of randomized controlled trials. Am Heart J. 2012 Feb;163(2):260-7.e3. doi: 10.1016/j.ahj.2011.11.014. Review.
Varma N, Jia P, Rudy Y Electrocardiographic imaging of patients with heart failure with left bundle branch block and response to cardiac resynchronization therapy. J Electrocardiol. 2007 Nov-Dec;40(6 Suppl):S174-8.
Zhang Q, Fang F, Yip GW, Chan JY, Shang Q, Fung JW, Chan AK, Liang YJ, Yu CM Difference in prevalence and pattern of mechanical dyssynchrony in left bundle branch block occurring in right ventricular apical pacing versus systolic heart failure. Am Heart J. 2008 Nov;156(5):989-95. doi: 10.1016/j.ahj.2008.06.027. Epub 2008 Sep 11.
Zhang Q, Fung JW, Chan JY, Yip G, Lam YY, Liang YJ, Yu CM Difference in long-term clinical outcome after cardiac resynchronisation therapy between ischaemic and non-ischaemic aetiologies of heart failure. Heart. 2009 Feb;95(2):113-8. doi: 10.1136/hrt.2008.145698. Epub 2008 Jul 24.
Zhang Q, Fung JW, Yip GW, Chan JY, Lee AP, Lam YY, Wu LW, Wu EB, Yu CM Improvement of left ventricular myocardial short-axis, but not long-axis function or torsion after cardiac resynchronisation therapy: an assessment by two-dimensional speckle tracking. Heart. 2008 Nov;94(11):1464-71. doi: 10.1136/hrt.2007.127498. Epub 2008 Jan 15.
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.