Cardiac Resynchronisation Therapy (CRT) for Heart failure

Heart failure is a condition where heart is unable to pump strong enough to meet the metabolic demands of the body. The incidence of heart failure is rising globally due to the ageing of the population and improved survival after myocardial infarction as quite a lot of these patients eventually develop heart failure due to LV dysfunction. Despite improvements in heart failure management the repeat hospitalisation rates and mortality continue to remain high in heart failure patients. The mortality at 1 year following an admission with heart failure is around 25% and the five-year mortality is between 40 -60% 1,2, that is why heart failure is also referred as a malignant condition because the prognosis is worse than some common cancers like breast cancer, ovarian cancer and some GI tract cancers.

Cardiac Resynchronisation Therapy is not a novel therapy for heart failure across the world but it still remains a novel therapy or not so widely used therapy in India. Severe heart failure patients develop what is called “Dyssynchrony” within the heart where various chambers of the heart do not function in a synchronised manner. There are three types of dyssynchrony – Atrio-ventricular dyssynchrony, Inter-ventricular dyssynchrony and Intra ventricular dyssynchrony, the latter being the most important form of dyssynchrony. This is visible on a surface ECG as Left Bundle Branch Block (LBBB) and this can also be assessed objectively using echocardiogram when it is called “Mechanical Dyssynchrony”. Heart failure patients with LV Ejection fraction < 35%, LBBB (QRS > 120msec) and who are symptomatic (NYHA Class III or IV) despite optimal medical therapy would benefit from Cardiac Resynchronisation therapy (CRT) using a biventricular pacemaker (CRT-P) or with a biventricular pacemaker + defibrillator (CRT-D)3-5. When patients, in addition to the above criteria, meet criteria for an ICD ie: high risk of sudden cardiac death, a CRT-D would be preferable6.

CRT implantation is a percutaneous procedure done under local anaesthesia in the Cath Lab. Using fluoroscopy three pacing leads, as shown in Figure 1, are positioned in the right atrial appendage, right ventricular apex and the posterolateral tributary of the Coronary sinus (via right atrium). An Atrio-biventricular pacing device is then implanted subcutaneously in the pectoral region. After implantation CRT device is optimised to reduce the three different forms of dyssynchrony.

Mrs MD is a 68 yr old lady with Severe Dilated Cardiomyopathy (LVEF- 25%) admitted with breathlessness on minimal exertion. She was symptomatic despite maximal medical therapy and had recurrent admissions with heart failure. She also had Parkinson’s disease with limited mobility. She underwent CRT-P implantation at Apollo Hospitals Ayanambakkam with three pacing leads as shown in Figure 2. The coronary sinus (CS) anatomy is visualised using a venogram after balloon occlusion of CS through the right atrium (Figure3). CS lead is then positioned in the posterolateral branch or the branch that is lateral and away from the apex to achieve optimal biventricular pacing. She had a significant improvement in her breathlessness post CRT implantation and now has a good quality of life despite her Parkinson’s disease.

CRT can be helpful in such patients with severe heart failure who remain symptomatic despite medical therapy. By reducing hospitalisations and readmission rates CRT implantation proves to be a cost effective therapy for sever heart failure patients and recent evidence show that CRT also reduces mortality even without a defibrillator.


Figure 1 showing the three pacing leads positioned in the right atrial appendage, right ventricle and coronary sinus.

Figure 2 showing the three pacing leads on fluoroscopy in the patient.

Figure 3 showing the venogram after balloon occlusion of the coronary sinus to visualise the tributaries for CS lead implantation

References :

  • Roger VL, Weston SA, Redfield MM, Hellermann-Homan JP, Killian J, Yawn BP, Jacobsen SJ. Trends in heart failure incidence and survival in a community-based population. JAMA 2004;292(3):344-350.
  • Levy D, Kenchaiah S, Larson MG, Benjamin EJ, Kupka MJ, Ho KK, Murabito JM, Vasan RS. Long-term trends in the incidence of and survival with heart failure. N Engl J Med. 2002;347(18):1397-1402.
  • Abraham WT, Fisher WG, Smith AL, Delurgio DB, Leon AR, Loh E, Kocovic DZ, Packer M, Clavell AL, Hayes DL, Ellestad M, Trupp RJ, Underwood J, Pickering F, Truex C, McAtee P, Messenger J; MIRACLE Study Group. Multicenter InSync Randomized Clinical Evaluation. Cardiac resynchronization in chronic heart failure. N Engl J Med. 2002;346:1845-1853.
  • Bristow MR, Saxon LA, Boehmer J, Krueger S, Kass DA, De Marco T, Carson P, DiCarlo L, DeMets D, White BG, DeVries DW, Feldman AM; Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION) Investigators. Cardiac-resynchronization therapy with or without an implantable defibrillator in advanced chronic heart failure. N Engl J Med. 2004;350:2140-5210.
  • Cleland JG, Daubert JC, Erdmann E, Freemantle N, Gras D, Kappenberger L, Tavazzi L; Cardiac Resynchronization-Heart Failure (CARE-HF) Study Investigators. The effect of cardiac resynchronization on morbidity and mortality in heart failure. N Engl J Med. 2005;52:1539-1549.
  • Young JB, Abraham WT, Smith AL, Leon AR, Lieberman R, Wilkoff B, Canby RC, Schroeder JS, Liem LB, Hall S, Wheelan K; Multicenter InSync ICD Randomized Clinical Evaluation (MIRACLE ICD) Trial Investigators. Combined cardiac resynchronization and implantable cardioversion defibrillation in advanced chronic heart failure: the MIRACLE ICD Trial. JAMA 2003;289:2685-2694.