We read with interest the study by Spirito et al about long-term outcomes in patients with hypertrophic cardiomyopathy (HCM) with benign presentation and free from conventional risk factors recently published in the The American Journal of Cardiology . A total of 653 relatively young patients (44.4 ± 16.8 years) were consecutively enrolled. The median length of follow-up was 5.3 years. The most important finding from this observational study is a not trivial event rate (0.6% per year), with unexpectedly high relative risk (RR) for sudden death (SD; 5.9%) and heart failure (8.2%), chiefly related to age (>60 years) and left atrial (LA) diameter (>40 mm).

The study is very attractive, but some issues deserve consideration. First of all, important prognosticators as the magnitude of left ventricular (LV) septum and the dynamic obstruction seem to lose their clinical meaning, at least with respect to clinical deterioration and SD, uncomforting previous milestone studies by the same Spirito et al. Moreover, the present study seems not to be prospectively rather retrospectively carried out on a data set from 7 worldwide clinical centers. This implies that echocardiographic measurements were not homogeneously taken, with no single-center echo-data reading, and this may have hampered some results. Although agreeing with the time-honored relation between LA size and atrial fibrillation, the reason why LA diameter >40 mm should increase the risk of SD (also heart failure–related death), irrespective of dynamic obstruction or greater LV mass, is not immediately understandable. A possible explanation is that these patients had greater mitral regurgitation or atrial fibrosis and subsequent higher LV filling pressure as a consequence of dynamic obstruction or severe diastolic dysfunction, but these findings are not confirmed to significantly affect clinical outcomes.

Also, we should consider that echocardiography guidelines have been updated (and still are), over the last few years, and clinicians are now aware that LA diameter achieved by M-mode modality has no longer to be considered such a reliable marker of atrial (dys)function, the indexed LA volume and/or the deformation analysis being much more stronger predictors. Thus, in our opinion, starting from their important findings, a new prospective multicenter trial on the prognostic weight of currently accepted LA morphofunctional markers is encouraged.

Finally, considering that only 10% (or less) of their initial study population reached a 15-year follow-up, the actuarial 10-year risk assessment should be preferred, hoping that, at least in younger patients (who are our major clinical concern), a much lower risk (0.2% to 0.3% per year?) might be supplied. Should this latter hypothesis come true, the 10-year cardiovascular death rate in young HCM patients might decrease close to 0.10% to 0.15%, which has been reported in 2012 by the World Health Organization in the general population from the United States. In this regard, O’Mahony et al recently quoted such a number of unnecessary implantable cardioverter-defibrillator implants in patients with HCM, stressing the need for alternative predicting scores.

Therefore, we are grateful to Dr. Spirito and coworkers because, while we all are aware of the HCM-related major clinical concerns, this study likely allows physicians to pronounce a word of comfort to most younger patients with HCM.