Heart failure · Resynchronization
CRT: getting both ventricles
to beat together again.
In left bundle branch block, the left ventricle contracts late and out of step, which wastes pumping effort. A CRT device paces both ventricles so they contract together. In the right patients it eases symptoms, reduces hospital admissions and improves survival.
Quick answer
Who is a candidate for CRT?
CRT is most clearly recommended for heart failure patients with an ejection fraction of 35% or less, sinus rhythm, left bundle branch block with a QRS of 150 ms or more, and symptoms despite optimised medication (class I in both US and European guidelines). It can also be useful with LBBB and a QRS of 120–149 ms (US) or 130–149 ms (ESC), or a non-LBBB QRS of 150 ms or more. In CARE-HF, CRT cut deaths from 30% to 20%.
20% vs 30%
Deaths, CRT vs medication
813 patients, NYHA III–IV, mean 29.4 months; HR 0.64
CARE-HF, NEJM 2005
−36%
Death risk with CRT-D
vs medication alone (P=0.003); CRT-P −24% (P=0.059)
COMPANION, NEJM 2004
−40%
Death or HF hospitalisation, CRT-D
−34% with CRT-P; 1,520 patients, NYHA III–IV, QRS ≥120 ms
COMPANION, NEJM 2004
17.2% vs 25.3%
Death or HF event, mild symptoms
CRT-ICD vs ICD alone, NYHA I–II, 1,820 patients
MADIT-CRT, NEJM 2009
41%
Fewer heart failure events
Seen mainly in patients with QRS ≥150 ms
MADIT-CRT, NEJM 2009
≥150 ms
QRS for class I
With LBBB — both 2022 US and 2021 ESC guidelines
AHA/ACC/HFSA 2022; ESC 2021
Device choice
CRT-P or CRT-D?
CRT-P
Three leads (right atrium, right ventricle, and a left-ventricular lead via the coronary sinus) to resynchronise contraction. Smaller and simpler, with no shock function.
Resynchronization
CRT-D
The same pacing plus a defibrillator. Chosen when the patient also meets ICD criteria, which many CRT candidates with an EF ≤35% do.
Resynchronization + shock
Conduction-system pacing
Some centres pace the heart's own conduction system (His bundle or left bundle branch area) as an alternative when a standard left-ventricular lead can't be placed. Ask whether the centre offers it.
Specialist option
Who qualifies
QRS width and shape decide most cases
CRT works by correcting electrical delay, so the ECG matters most. Patients with a typical left bundle branch block and a QRS of 150 ms or more benefit most. The benefit shrinks with narrower QRS or non-LBBB patterns. Below 130 ms, the ESC advises against CRT unless the patient needs ventricular pacing for another reason.
| ECG | 2022 AHA/ACC/HFSA | 2021 ESC |
|---|---|---|
| LBBB, QRS ≥150 ms | Class 1 | Class I |
| LBBB, QRS 130–149 ms | Class 2a (from 120 ms) | Class IIa |
| LBBB, QRS 120–129 ms | Class 2a | Not recommended |
| Non-LBBB, QRS ≥150 ms | Class 2a | Class IIa |
| Non-LBBB, QRS 130–149 ms | Class 2b (NYHA III–ambulatory IV) | Class IIb |
Simplified. The US guideline's non-LBBB 120–149 ms recommendation applies to NYHA III–ambulatory IV; full criteria in the cited guidelines.
The evidence
Three trials that established CRT
COMPANION and CARE-HF showed that CRT improves survival in patients with significant symptoms. MADIT-CRT extended the benefit to milder symptoms (NYHA I–II). There it reduced heart failure events but not overall mortality during the 2.4-year follow-up, and the benefit was concentrated in patients with QRS ≥150 ms.
| Trial | Patients | Main result |
|---|---|---|
| COMPANION (NEJM 2004) | 1,520 · NYHA III–IV, QRS ≥120 ms | Death or HF hospitalisation −34% (CRT-P) and −40% (CRT-D); death −24% (P=0.059) and −36% (P=0.003) |
| CARE-HF (NEJM 2005) | 813 · NYHA III–IV with dyssynchrony | Death or CV hospitalisation 39% vs 55%; death 20% vs 30% (HR 0.64) |
| MADIT-CRT (NEJM 2009) | 1,820 · NYHA I–II, EF ≤30%, QRS ≥130 ms | Death or HF event 17.2% vs 25.3% (HR 0.66); no mortality difference (≈3%/year in both arms) |
Arrhythmia centres
Where CRT is
implanted in China.
Fuwai Hospital 阜外医院
National Center for Cardiovascular Diseases; arrhythmia and heart failure programme
Beijing Anzhen Hospital 北京安贞医院
Major cardiology centre with an advanced heart failure programme
Zhongshan Hospital, Fudan University 复旦大学附属中山医院
Shanghai's leading cardiology department
FAQ
CRT questions — answered.
- Will CRT make me feel better?
- Many patients do feel better. In CARE-HF, CRT improved symptoms and quality of life and increased ejection fraction. However, not everyone responds; the chance is highest with LBBB and a QRS of 150 ms or more. Your cardiologist will look at the ECG pattern to estimate your likelihood of benefit.
- Should I get CRT-P or CRT-D?
- If you also meet ICD criteria, which is common with an EF of 35% or less, a CRT-D is usually chosen. A CRT-P may be preferred in older patients or those with significant other illness, where a defibrillator is less likely to add years of life. Discuss this trade-off with your cardiologist.
- My QRS is 125 ms. Do I qualify?
- It depends on the guideline and the QRS shape. With LBBB, the US guideline gives a class 2a recommendation from 120 ms; the ESC does not recommend CRT below 130 ms. If you don't qualify for CRT, cardiac contractility modulation (CCM) may be an option if your EF is 25–45%.
- How long does the procedure take, and when can I fly?
- CRT implantation is longer than an ICD implant, because the left-ventricular lead has to be placed through the coronary sinus. We suggest planning about a week in China for the procedure, wound check and device optimisation before flying home with your device card.
Related guides
Heart failure treatment (hub)
The step-by-step pathway from medication to devices, LVAD and transplant.
Read the guideICD for sudden-death prevention
Single-, dual-chamber and extravascular ICDs; who qualifies at EF ≤35%.
Read the guideCardiac contractility modulation (CCM)
A device option for narrow QRS, EF 25–45% — approved in China.
Read the guideLVAD (artificial heart pump)
HeartMate 3 and Chinese-made pumps: outcomes and approvals.
Read the guideHeart transplant in China
Outcomes, volumes — and the rules for foreign patients.
Read the guideCardiac surgery in China
Bypass, valve surgery, TAVR and other procedures that treat reversible causes.
Read the guideSources
References
- Bristow MR, et al. Cardiac-resynchronization therapy with or without an implantable defibrillator in advanced chronic heart failure (COMPANION). N Engl J Med. 2004;350(21):2140–2150.
- Cleland JG, et al. The effect of cardiac resynchronization on morbidity and mortality in heart failure (CARE-HF). N Engl J Med. 2005;352(15):1539–1549.
- Moss AJ, et al. Cardiac-resynchronization therapy for the prevention of heart-failure events (MADIT-CRT). N Engl J Med. 2009;361(14):1329–1338.
- Heidenreich PA, et al. 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure: Executive Summary. J Am Coll Cardiol. 2022;79(17):1757–1780.
- McDonagh TA, et al. 2021 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure. Eur Heart J. 2021;42(36):3599–3726.
- Glikson M, et al. 2021 ESC Guidelines on cardiac pacing and cardiac resynchronization therapy. Eur Heart J. 2021;42(35):3427–3520.
Send your ECG
and find out if CRT fits.
Share a recent 12-lead ECG, echocardiogram and medication list. A partner cardiologist will tell you whether your QRS width and pattern meet CRT criteria, and whether CRT-P, CRT-D or another option fits better.
This page is for general education only and is not medical advice. Device and surgical treatment for heart failure depends on your ejection fraction, ECG, symptoms, other conditions and how you respond to medication, and only your cardiologist can decide what fits. Trial results describe groups of patients, not what will happen to you. We are an independent patient-coordination service and are not affiliated with any device manufacturer.