Cardiac resynchronization in heart failure: Recent advances and their practical implications

Cardiac resynchronisation (CRT) improves survival and reduces heart failure hospitalisations, in symptomatic patients with heart failure (HF) with reduced ejection fraction with wide QRS despite guidelines indicated medical therapy. In patients with mild HF symptoms (New York Heart Association [NYHA], class II) CRT delays or reverses disease progression. Still, CRT is largely underused. The results of CRT Survey II indicates wide adoption of class I indications in European Society of Cardiology guidelines but with important national differences. As an example more patients in Poland had ischemic HF etiology and in NYHA III than in the overall CRT cohort. Similar patterns were seen in other countries suggesting that some patients such as those in NYHA II and with non-ischemic etiology may be especially underserved by CRT. But the Survey results also shows wide use in areas with week scientific evidence such in atrial fibrillation (AF) and when upgrading from ongoing implantable cardioverter defibrillator or right ventricular pacing to CRT. This practise may imply the belief of the physcian than CRT may but also highlights the need of randomised studies to elucidate CRT effects in such patients. Besides, gaps of evidence the review further discusses reasons for obstacles for CRT implementation and the challenges with the traditional responder definition which may deter the clinician from offering CRT therapy. Finally, the importance of sex and body size for electrical selection criteria for CRT are discussed. A person with small body size and/or female sex may may derive CRT benefit at shorter QRS durations than a bigger individual indicating the need ato shift to personalized medicine