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| | __NOTOC__ |
| | {| class="infobox" style="float:right;" |
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| | | [[File:Siren.gif|30px|link= Congestive heart failure resident survival guide]]|| <br> || <br> |
| | | [[Acute decompensated heart failure resident survival guide|'''Resident'''<br>'''Survival'''<br>'''Guide''']] |
| | |} |
| | {| class="infobox" style="float:right;" |
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| | | [[File:Critical_Pathways.gif|88px|link= Congestive heart failure critical pathways]]|| <br> || <br> |
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| {{Cardiac resynchronization therapy}} | | {{Cardiac resynchronization therapy}} |
| {{CMG}}; {{AOEIC}}: Bhaskar Purushottam, M.D. [mailto:bpurushottam@gmail.com] | | {{CMG}}; {{AOEIC}}: Bhaskar Purushottam, M.D. [mailto:bpurushottam@gmail.com] |
| '''''Synonyms and Keywords:''''' CRT
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| ==Overview==
| | {{SK}} CRT |
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| ==Landmark Trials== | | ==[[Cardiac resynchronization therapy overview|Overview]]== |
| The several landmark trials which led to the acceptance of CRT as a non-pharmacological treatment approach for heart failure almost exclusively enrolled patients with sinus rhythm and a left bundle branch block (especially, with a QRS duration greater than or equal to 0.15 seconds). However, QRS duration greater than or equal to 0.12 seconds has been used a measure for dyssynchrony and a criterion for selection of patients for CRT. It is thought that when the QRS duration is prolonged there is delayed activation of the ventricular myocardium with dyssynchronous contraction between the left and right ventricle (interventricular dyssynchrony) and within the left ventricle itself (intraventricular dyssynchrony). However, left ventricular mechanical dyssynchrony is shown to occur independent of QRS duration by echocardiographic parameters (predominantly tissue Doppler and speckle tracking imaging), which measure inter and intra left ventricular conduction delay. By such parameters, nearly half of the heart failure patients with normal QRS duration have evidence of mechanical dyssynchrony and one fifth of heart failure patients with QRS duration greater than or equal to 0.15 seconds reveal no evidence of mechanical dyssynchrony<ref name="pmid14736445">{{cite journal| author=Bader H, Garrigue S, Lafitte S, Reuter S, Jaïs P, Haïssaguerre M et al.| title=Intra-left ventricular electromechanical asynchrony. A new independent predictor of severe cardiac events in heart failure patients. | journal=J Am Coll Cardiol | year= 2004 | volume= 43 | issue= 2 | pages= 248-56 | pmid=14736445 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14736445 }} </ref><ref name="pmid16360052">{{cite journal| author=Cho GY, Song JK, Park WJ, Han SW, Choi SH, Doo YC et al.| title=Mechanical dyssynchrony assessed by tissue Doppler imaging is a powerful predictor of mortality in congestive heart failure with normal QRS duration. | journal=J Am Coll Cardiol | year= 2005 | volume= 46 | issue= 12 | pages= 2237-43 | pmid=16360052 | doi=10.1016/j.jacc.2004.11.074 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16360052 }} </ref>. It has also been shown that mechanical dyssynchrony measured by echocardiographic techniques is predictive of cardiac events in heart failure patients independent of their QRS duration<ref name="pmid16360052">{{cite journal| author=Cho GY, Song JK, Park WJ, Han SW, Choi SH, Doo YC et al.| title=Mechanical dyssynchrony assessed by tissue Doppler imaging is a powerful predictor of mortality in congestive heart failure with normal QRS duration. | journal=J Am Coll Cardiol | year= 2005 | volume= 46 | issue= 12 | pages= 2237-43 | pmid=16360052 | doi=10.1016/j.jacc.2004.11.074 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16360052 }} </ref>. Therefore, using QRS duration, which is an electrical measure of conduction delay may not be the most reliable marker of ventricular dyssynchrony. The RethinQ<ref name="pmid17986493">{{cite journal| author=Beshai JF, Grimm RA, Nagueh SF, Baker JH, Beau SL, Greenberg SM et al.| title=Cardiac-resynchronization therapy in heart failure with narrow QRS complexes. | journal=N Engl J Med | year= 2007 | volume= 357 | issue= 24 | pages= 2461-71 | pmid=17986493 | doi=10.1056/NEJMoa0706695 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17986493 }} </ref> trial failed to show any benefit from CRT in heart failure patients with a NYHA class 3, left ventricular ejection fraction less than or equal to 35%, narrow QRS duration(less than or equal to 0.13 seconds) with mechanical dyssynchrony as measured by tissue Doppler imaging and M-mode echocardiography. One of the major limitations of this study was the selection criteria for mechanical dyssynchrony. Currently, there are several studies underway which are looking at different echocardiographic techniques to predict intra left ventricular mechanical dyssynchrony accurately. Till we have a feasible, convenient, reproducible and accurate technique to measure mechanical intra left ventricular dyssynchrony, QRS duration will be used as a measure of dyssynchrony in selecting patients for CRT. CRT in responders can reverse the above mentioned hemodynamic abnormalities to a certain extent with associated clinical and functional benefit.
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| ===Efficacy in Clinical Trials=== | | ==[[Cardiac resynchronization therapy indications|Indications]]== |
| PATH-CHF<ref name="pmid10089855">{{cite journal| author=Auricchio A, Stellbrink C, Sack S, Block M, Vogt J, Bakker P et al.| title=The Pacing Therapies for Congestive Heart Failure (PATH-CHF) study: rationale, design, and endpoints of a prospective randomized multicenter study. | journal=Am J Cardiol | year= 1999 | volume= 83 | issue= 5B | pages= 130D-135D | pmid=10089855 | doi= | pmc= | url= }} </ref>, MUSTIC SR<ref name="pmid11259720">{{cite journal| author=Cazeau S, Leclercq C, Lavergne T, Walker S, Varma C, Linde C et al.| title=Effects of multisite biventricular pacing in patients with heart failure and intraventricular conduction delay. | journal=N Engl J Med | year= 2001 | volume= 344 | issue= 12 | pages= 873-80 | pmid=11259720 | doi=10.1056/NEJM200103223441202 | pmc= | url= }} </ref><ref name="pmid12103264">{{cite journal| author=Linde C, Leclercq C, Rex S, Garrigue S, Lavergne T, Cazeau S et al.| title=Long-term benefits of biventricular pacing in congestive heart failure: results from the MUltisite STimulation in cardiomyopathy (MUSTIC) study. | journal=J Am Coll Cardiol | year= 2002 | volume= 40 | issue= 1 | pages= 111-8 | pmid=12103264 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12103264 }} </ref>, MUSTIC AF<ref name="pmid12419298">{{cite journal| author=Leclercq C, Walker S, Linde C, Clementy J, Marshall AJ, Ritter P et al.| title=Comparative effects of permanent biventricular and right-univentricular pacing in heart failure patients with chronic atrial fibrillation. | journal=Eur Heart J | year= 2002 | volume= 23 | issue= 22 | pages= 1780-7 | pmid=12419298 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12419298 }} </ref>, MIRACLE<ref name="pmid12063368">{{cite journal| author=Abraham WT, Fisher WG, Smith AL, Delurgio DB, Leon AR, Loh E et al.| title=Cardiac resynchronization in chronic heart failure. | journal=N Engl J Med | year= 2002 | volume= 346 | issue= 24 | pages= 1845-53 | pmid=12063368 | doi=10.1056/NEJMoa013168 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12063368 }} [http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12418822 Review in: ACP J Club. 2002 Nov-Dec;137(3):82] </ref>, COMPANION<ref name="pmid15152059">{{cite journal| author=Bristow MR, Saxon LA, Boehmer J, Krueger S, Kass DA, De Marco T et al.| title=Cardiac-resynchronization therapy with or without an implantable defibrillator in advanced chronic heart failure. | journal=N Engl J Med | year= 2004 | volume= 350 | issue= 21 | pages= 2140-50 | pmid=15152059 | doi=10.1056/NEJMoa032423 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15152059 }} [http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15518444 Review in: ACP J Club. 2004 Nov-Dec;141(3):60] </ref>, CARE-HF<ref name="pmid15753115">{{cite journal| author=Cleland JG, Daubert JC, Erdmann E, Freemantle N, Gras D, Kappenberger L et al.| title=The effect of cardiac resynchronization on morbidity and mortality in heart failure. | journal=N Engl J Med | year= 2005 | volume= 352 | issue= 15 | pages= 1539-49 | pmid=15753115 | doi=10.1056/NEJMoa050496 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15753115 }} [http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16134903 Review in: ACP J Club. 2005 Sep-Oct;143(2):29] </ref>, MIRACLE-ICD<ref name="pmid12771115">{{cite journal| author=Young JB, Abraham WT, Smith AL, Leon AR, Lieberman R, Wilkoff B et al.| title=Combined cardiac resynchronization and implantable cardioversion defibrillation in advanced chronic heart failure: the MIRACLE ICD Trial. | journal=JAMA | year= 2003 | volume= 289 | issue= 20 | pages= 2685-94 | pmid=12771115 | doi=10.1001/jama.289.20.2685 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12771115 }} </ref>, CONTAK-CD<ref name="pmid14563591">{{cite journal| author=Higgins SL, Hummel JD, Niazi IK, Giudici MC, Worley SJ, Saxon LA et al.| title=Cardiac resynchronization therapy for the treatment of heart failure in patients with intraventricular conduction delay and malignant ventricular tachyarrhythmias. | journal=J Am Coll Cardiol | year= 2003 | volume= 42 | issue= 8 | pages= 1454-9 | pmid=14563591 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14563591 }} </ref>, RHYTHM-ICD and HOBIPACE<ref name="pmid16697307">{{cite journal| author=Kindermann M, Hennen B, Jung J, Geisel J, Böhm M, Fröhlig G| title=Biventricular versus conventional right ventricular stimulation for patients with standard pacing indication and left ventricular dysfunction: the Homburg Biventricular Pacing Evaluation (HOBIPACE). | journal=J Am Coll Cardiol | year= 2006 | volume= 47 | issue= 10 | pages= 1927-37 | pmid=16697307 | doi=10.1016/j.jacc.2005.12.056 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16697307 }} </ref> landmark trials demonstrated the following beneficial effects of CRT:
| | : [[Cardiac resynchronization therapy landmark trials|Landmark Trials]] |
| #Reduced mortality (24% to 36% benefit)
| | :'''[[Cardiac resynchronization therapy special populations|Special Populations]]''': [[Cardiac resynchronization therapy special populations#Atrial Fibrillation and CRT|Atrial Fibrillation Patients]] | [[Cardiac resynchronization therapy special populations#Cardiac Resynchronization Therapy in Minimal Heart Failure|Minimal Heart Failure Patients]] |
| #Reduced hospitalizations (30% decrease)
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| #Improved 6 minute walk test (50 to 70 meter increase)
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| #Improved 105 -point Minnesota scale (greater than or equal to 10 point reduction of [[heart failure]] symptoms)
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| #Improved NYHA class
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| #Increase in peak oxygen consumption
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| ==References== | | ==[[Cardiac resynchronization therapy contraindications|Contraindications]]== |
| {{reflist|2}}
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| {{WH}}
| | ==[[Cardiac resynchronization therapy pathophysiology|Pathophysiologic Basis For CRT]]== |
| {{WS}}
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| | ==[[Cardiac resynchronization therapy procedure|Procedure]]== |
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| | ==[[Cardiac resynchronization therapy prognosis|Outcomes and Prognosis]]== |
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| | ==[[Cardiac resynchronization therapy complications|Complications]]== |
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| | ==Related Chapters== |
| | * [[Congestive heart failure]] |
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| | [[Category:Cardiology]] |
| | [[Category:Disease]] |
| | [[Category:Emergency medicine]] |
| | [[Category:Intensive care medicine]] |
| | [[Category:Medicine]] |
| | [[Category:Up-To-Date]] |
| | [[Category:Up-To-Date cardiology]] |
