The aim of this Research Topic is to explore the limitations of dimensionless ratio-based metrics, commonly applied in cardiovascular medicine. Examples are ejection fraction, arterial pressure augmentation index, and coronary fractional flow reserve. Focusing on a single number as reflected by the ratio implies that information is lost. To overcome these simplifications it is required to formulate alternative routes of data representation. Such transformations may provide better insight into underlying physiology and therefore enrich interpretation of clinical data.
Frequently used indicators of cardiac “function” or coronary “reserve capacity” often carry no physical dimension, as they are actually a composite of paired data such as ventricular volume at end-systole and end-diastole, or flow at baseline versus hyperemic level. The physical units of the measurements then vanish in the ratio, resulting in a bare number that does not uniquely characterize the situation. Transformation to polar coordinates enables identification of a companion metric, and may offer the clue to a physiologically relevant interpretation.
Within this context a special area of concern refers to the statistical comparison of ratios. Outcomes depend on the preferred choice of variables in numerator and denominator, while the ratio is not a variable on a linear scale.
Initial advances in this field have been made, e.g. the identification of mean arterial pressure as a companion metric to pulse pressure, or the introduction of preload as a surrogate biomarker associated with the companion to ejection fraction.
Especially contributions by clinically oriented physiologists are welcome, and potential topics include but are not limited to:
1) Cardiac imaging and physiology.
2) Hemodynamic parameters referring to ratios.
3) Coronary flow assessment and hyperemia.
4) Age- and sex-specific aspects of cardiovascular metrics.
5) Statistical evaluation of ratios.
6) Comparison of data obtained by various cardiac imaging modalities.
7) Ratio-free phenotyping of heart failure.
The aim of this Research Topic is to explore the limitations of dimensionless ratio-based metrics, commonly applied in cardiovascular medicine. Examples are ejection fraction, arterial pressure augmentation index, and coronary fractional flow reserve. Focusing on a single number as reflected by the ratio implies that information is lost. To overcome these simplifications it is required to formulate alternative routes of data representation. Such transformations may provide better insight into underlying physiology and therefore enrich interpretation of clinical data.
Frequently used indicators of cardiac “function” or coronary “reserve capacity” often carry no physical dimension, as they are actually a composite of paired data such as ventricular volume at end-systole and end-diastole, or flow at baseline versus hyperemic level. The physical units of the measurements then vanish in the ratio, resulting in a bare number that does not uniquely characterize the situation. Transformation to polar coordinates enables identification of a companion metric, and may offer the clue to a physiologically relevant interpretation.
Within this context a special area of concern refers to the statistical comparison of ratios. Outcomes depend on the preferred choice of variables in numerator and denominator, while the ratio is not a variable on a linear scale.
Initial advances in this field have been made, e.g. the identification of mean arterial pressure as a companion metric to pulse pressure, or the introduction of preload as a surrogate biomarker associated with the companion to ejection fraction.
Especially contributions by clinically oriented physiologists are welcome, and potential topics include but are not limited to:
1) Cardiac imaging and physiology.
2) Hemodynamic parameters referring to ratios.
3) Coronary flow assessment and hyperemia.
4) Age- and sex-specific aspects of cardiovascular metrics.
5) Statistical evaluation of ratios.
6) Comparison of data obtained by various cardiac imaging modalities.
7) Ratio-free phenotyping of heart failure.
