Epidemiology and impact of frailty in patients with atrial fibrillation in Europe

BACKGROUND

Frailty is a medical syndrome characterised by reduced physiological reserve and increased vulnerability to stressors. Data regarding the relationship between frailty and atrial fibrillation (AF) are still inconsistent.

OBJECTIVES

We aim to perform a comprehensive evaluation of frailty in a large European cohort of AF patients.

METHODS

A 40-item frailty index (FI) was built according to the accumulation of deficits model in the AF patients enrolled in the ESC-EHRA EORP-AF General Long-Term Registry. Association of baseline characteristics, clinical management, quality of life, healthcare resources use and risk of outcomes with frailty was examined.

RESULTS

Among 10,177 patients [mean age (standard deviation) 69.0 (11.4) years, 4,103 (40.3%) females], 6,066 (59.6%) were pre-frail and 2,172 (21.3%) were frail, whereas only 1,939 (19.1%) were considered robust. Baseline thromboembolic and bleeding risks were independently associated with increasing FI. Frail patients with AF were less likely to be treated with oral anticoagulants (OACs) (odds ratio 0.70, 95% confidence interval 0.55-0.89), especially with non-vitamin K antagonist OACs and managed with a rhythm control strategy, compared with robust patients. Increasing frailty was associated with a higher risk for all outcomes examined, with a non-linear exponential relationship. The use of OAC was associated with a lower risk of outcomes, except in patients with very/extremely high frailty.

CONCLUSIONS

In this large cohort of AF patients, there was a high burden of frailty, influencing clinical management and risk of adverse outcomes. The clinical benefit of OAC is maintained in patients with high frailty, but not in very high/extremely frail ones.

Magnification functions and receptive field sequences for submodality-specific bands in SI cortex of cats

Electrophysiological data were collected from the forelimb region of somatosensory cortex in barbiturate-anesthetized cats using low-impedance microelectrodes in long slanting trajectories. Subsequently, the brains were fixed and stained with thionin to locate the electrode trajectories and to correlate cytoarchitecture with neural activity. Confirming earlier experiments, regions of cortex, preferentially responsive to one submodality of afferent input, were observed to stretch in mediolateral bands across SI. Separate magnification functions were calculated for each band. In the forelimb region the magnification functions for the deep and cutaneous RA bands could be approximated by linear functions while the data for the cutaneous SA band was best described by a second-order equation. At least in the forelimb region this magnification function applied only along the anteroposterior dimension of the band because the body representation is anisotropic; along the anteroposterior dimension of the band, receptive field loci may change only millimeters on the skin when the electrode moves through 1 mm of cortex, whereas when an electrode moves in a mediolateral direction they change centimeters on the forearm for an equivalent cortical distance. Each representation is separated from the others by a transition zone having a minimal width less than 200 micron. Within the transition zones, neurons often have receptive field loci which are a compromise between loci found in the adjacent representations. In these zones responses are often difficult to elicit. Electrode penetrations encountering these transition zones contain data which fulfill the receptive field and modality criteria for the boundary of a cortical column. However, within the mediolateral length of each submodality band we have found no unit with a dimension greater than 200 micron which has a boundary or transition zone. Evidence for units of smaller size cannot be obtained because of limitations in the data collection techniques. Thus, within each submodality-specific band, large portions of the somatotopic map appear to be a mediolateral continuum while relatively abrupt changes occur in receptive field locus and in submodality when the electrode passes through a transition zone between adjacent bands.