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We read with great interest the report by Achilli et al. (1) on cardiac resynchronization therapy (CRT) in patients with heart failure (HF) and narrow QRS: the clinical implication of those data is huge in light of the rapidly expanding indications for CRT.
Achilli et al. (1) described the “long-term” efficacy of CRT in 52 patients (all preselected by echocardiographic recognition of inter- and intraventricular dyssynchrony) affected by HF, 14 of them with a QRS ≤120 ms. Positive results were obtained both from a clinical and echocardiographic point of view.
The fact that the mean follow-up was ∼565 days, but that the “clinical and echocardiographic results” refer to the six-month follow-up, could be a bit confusing. This may be misleading, and no doubt the definition of “mid-term” rather than “long-term” would be more appropriate in describing the follow-up by Achilli et al. (1).
Our larger experience (158 patients, mean follow-up 1 year) (2), published just a year before Achilli et al. (1) study (and probably overlooked by the investigators) also confirms positive results of CRT in patients with narrow QRS. Based purely on basal QRS duration, without preselection by any echocardiographic parameter, our patients were defined as wide QRS (≥150 ms, 128 patients) and narrow QRS (<150 ms, 30 patients, 13 with QRS ≤120 ms, a number comparable to the Achilli et al.  narrow QRS cohort). Our data confirm that, in both groups, CRT significantly improved clinical and echocardiographic parameters; in our series these good results were sustained for at least one year.
The most relevant difference between Achilli et al's. (1) and our population concerns the mortality rate in the narrow QRS group; in fact, the 21.4% reported by Achilli et al. (1) in patients with narrow QRS strongly contrasted with no deaths in our series. In addition, the mortality rate reported by the investigators was similar in patients with both narrow and wide QRS duration, being substantially higher than other reported series.
Finally, we agree that echocardiographic indicators of dyssynchrony can be useful; nonetheless, our data on patients with narrow QRS have clearly demonstrated that the use of pure “clinical” selection criteria (i.e., drug refractoriness, severe HF, low ejection fraction, large diameters) has permitted us to identify patients who can substantially benefit from CRT in the long term.
- American College of Cardiology Foundation