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Aims Heart rate reduction therapy using ivabradine, a selective inhibitor of the funny current of the sinoatrial node, is widely used in the systolic heart failure cohort. However, the optimal target of heart rate remains controversial. The association between heart rate and 'overlap' between E-wave and A-wave in the pulse wave transmitral flow Doppler echocardiography might be a key to find the ideal heart rate in each individual. Methods and results We performed transthoracic echocardiography in patients with systolic heart failure, and the association between heart rate, deceleration time, and overlap length between E-wave and A-wave was assessed. In total, 368 patients with systolic heart failure (median 76 years old, 190 men, median ejection fraction 40%) were included. The measured overlap length was 35 (À72, 115) ms. Given the results of multiple linear regression analyses, we constructed a formula: estimated overlap length (ms) = À589 + 6.2 × heart rate (bpm) + 0.81 × deceleration time (ms), which had a good agreement with actually measured one (r = 0.62). The ideal heart rate, at which the overlap length is 'zero' and probably cardiac output is maximized, is calculated as follows: ideal heart rate (bpm) = 93-0.13 × deceleration time (ms). Conclusions We proposed a novel formula using deceleration time to estimate ideal heart rate that achieves a zero overlap between E-wave and A-wave in patients with systolic heart failure. Prognostic impact of the formula-guided heart rate optimization should be studied.

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Background: The accuracy of the remote dielectric sensing (ReDSTM) system, which is a noninvasive electromagnetic-based technology to quantify lung fluid levels, particularly among those with small body size, remains uncertain. Methods: Hospitalized patients with and without heart failure underwent assessment of lung fluid levels with ReDS and successive chest computed tomography imaging. We performed a correlation analysis of the ReDS measurement, representing lung fluid levels, and computed tomography-derived high attenuation area percentage, which also provides a spatial quantification of lung fluid level. Results: A total of 46 patients (median 76 years old, 28 men), including 28 patients with heart failure, were included. The median ReDS value was 28% (interquartile: 23%, 33%), and the median percentage of high attenuation area was 21.6% (14.4%, 28.5%). ReDS values and percentage of high attenuation area were moderately correlated (r = 0.65, p < 0.001), irrespective of the existence of heart failure. ReDS value independently predicted the percentage of high attenuation area seen on computed tomography (p < 0.001). Conclusions: The ReDS system may be a promising, noninvasive tool to quantify fluid lung levels, as validated by comparison with chest computed tomography imaging. Further studies are warranted to validate the utility and applicability of this technology to a variety of clinical scenarios.