Patient motivation and adherence to an on-demand app-based heart rate and rhythm monitoring for atrial fibrillation management: data from the TeleCheck-AF project

AIMS

The aim of this TeleCheck-AF sub-analysis was to evaluate motivation and adherence to on-demand heart rate/rhythm monitoring app in patients with atrial fibrillation (AF).

METHODS AND RESULTS

Patients were instructed to perform 60 s app-based heart rate/rhythm recordings 3 times daily and in case of symptoms for 7 consecutive days prior to teleconsultation. Motivation was defined as number of days in which the expected number of measurements (≥3/day) were performed per number of days over the entire prescription period. Adherence was defined as number of performed measurements per number of expected measurements over the entire prescription period.Data from 990 consecutive patients with diagnosed AF [median age 64 (57-71) years, 39% female] from 10 centres were analyzed. Patients with both optimal motivation (100%) and adherence (≥100%) constituted 28% of the study population and had a lower percentage of recordings in sinus rhythm [90 (53-100%) vs. 100 (64-100%), P < 0.001] compared with others. Older age and absence of diabetes were predictors of both optimal motivation and adherence [odds ratio (OR) 1.02, 95% coincidence interval (95% CI): 1.01-1.04, P < 0.001 and OR: 0.49, 95% CI: 0.28-0.86, P = 0.013, respectively]. Patients with 100% motivation also had ≥100% adherence. Independent predictors for optimal adherence alone were older age (OR: 1.02, 95% CI: 1.00-1.04, P = 0.014), female sex (OR: 1.70, 95% CI: 1.29-2.23, P < 0.001), previous AF ablation (OR: 1.35, 95% CI: 1.03-1.07, P = 0.028).

CONCLUSION

In the TeleCheck-AF project, more than one-fourth of patients had optimal motivation and adherence to app-based heart rate/rhythm monitoring. Older age and absence of diabetes were predictors of optimal motivation/adherence.

Frequency and Determinants of Spontaneous Conversion to Sinus Rhythm in Patients Presenting to the Emergency Department with Recent-onset Atrial Fibrillation: A Systematic Review

The exact frequency and clinical determinants of spontaneous conversion (SCV) in patients with symptomatic recent-onset AF are unclear. The aim of this systematic review is to provide an overview of the frequency and determinants of SCV of AF in patients presenting at the emergency department. A comprehensive literature search for studies about SCV in patients presenting to the emergency department with AF resulted in 25 articles - 12 randomised controlled trials and 13 observational studies. SCV rates range between 9-83% and determinants of SCV also varied between studies. The most important determinants of SCV included short duration of AF (<24 or <48 hours), low number of episodes, normal atrial dimensions and absence of previous heart disease. The large variation in SCV rate and determinants of SCV was related to differences in duration of the observation period, inclusion and exclusion criteria and in variables used in the prediction models.

Activation of the Na+/K+ pump current by intra- and extracellular Li ions in single guinea-pig cardiac cells

Li+ is the only ion that can replace the physiological intra- and extracellular activator cations of the Na+/K+ pump. In order to study this singular property of Li+ in some detail, the activation of the Na+/K+ pump current (Ip) by intra- and extracellular Li+ (Li+; Li[o]+) was measured in isolated guinea-pig ventricular myocytes by means of whole cell recording at 34 degrees C and a holding potential of -20 mV. Ip was identified as current blocked by dihydro-ouabain. Half-maximal Ip activation occurred at 23 mM Li(o)+ (K0.5 value) in cells containing Na+ (50 or 100 mM) and at 73 mM Li(o)+ in myocytes containing Li+ (100 mM). The K0.5 value of Ip activation by Li(o)+ increased with depolarisation, suggesting the transfer of 0.2 of an elementary charge across the electric field of the sacrolemma during Li(o)+-binding. An intracellular Li+ concentration of 36 mM caused half-maximal Ip activation in cells superfused with Na+- and Li+-free media containing 1 mM K+. In Na+-free solutions. the Ip-V curve displayed a positive slope at negative membrane potentials. A negative slope at positive potentials was observed in Li+-containing media. It is concluded that Li+ is less efficacious and potent than the physiological pump activator cations. The shape of the Ip-V curves in Na+-free solutions supports the view that the cardiac Na+/K+ pump contains a channel-like structure and suggests that there are voltage-sensitive steps in the pump cycle, apart from the binding of external cations.

The antagonistic effect of K+o and dihydro-ouabain on the Na+ pump current of single rat and guinea-pig cardiac cells

1. The antagonistic effect of extracellular potassium ions (K+o) and dihydro-ouabain (DHO) on the Na(+)-K+ pump current (Ip) was studied in isolated ventricular cells. 2. The myocytes were isolated from rats and guinea-pigs, two species with different sensitivity towards cardiac glycosides. Ip measurements were performed at 32-34 degrees C by means of whole-cell recording. The membrane potential was held at -20 mV throughout. 3. The DHO concentration ([DHO]) required for half-maximal Ip inhibition (apparent KD value, KD') amounted to 2.4 x 10(-3) and 1.4 x 10(-5) M for rat and guinea-pig myocytes, respectively, at 5.4 mM K+o. 4. The data suggest one-to-one binding of DHO to the Na(+)-K+ pump and a smaller association rate constant, as well as a larger dissociation rate constant, for binding of DHO in the rat cells. 5. Ip activation by K+o was nearly identical in myocytes of both species and was measured to be half-maximal at approximately 1 mM K+o. Half-maximal Ip activation by K+o remained essentially unchanged, but Ip decreased in media containing [DHO] near the respective KD' at 5.4 mM K+o. 6. The concentration-response curve of Ip inhibition by DHO was shifted to higher [DHO] at higher [K+]o. KD' increased correspondingly. The slope of the curve was unaffected. 7. Ip and KD' displayed a similar dependence on [K+]o. 8. KD' was larger in Na(+)-free than in Na(+)-containing media under conditions in which the activation of Ip by K+o was nearly the same. 9. It is concluded that the antagonism between K+o and DHO, with regard to the activation of Ip, is non-competitive. A possible mechanism of the antagonism is discussed. The mechanism implies binding of K+o and DHO to different conformational states of the Na(+)-K+ pump which are temporarily exposed to the external face of the sarcolemma in the pump cycle. The DHO-bound states do not participate in the generation of Ip.

The effect of cardiac glycosides on the Na+ pump current-voltage relationship of isolated rat and guinea-pig heart cells

1. Whole-cell recording from isolated rat and guinea-pig ventricular myocytes revealed a change of the cardiac Na+ pump current (Ip)-voltage (V) relationship by cardiac glycosides, specific inhibitors of the Na(+)-K+ pump. 2. Dihydro-ouabain (DHO) diminished Ip in rat ventricular cells at 0 mV in a concentration-dependent manner. 3. The concentration-response curve of Ip inhibition caused by DHO was shifted to higher [DHO] at higher extracellular K+ concentrations ([K+]o) or at more negative membrane potentials. 4. In rat myocytes, DHO immediately flattened the normalized cardiac Ip-V curve and evoked or enhanced a region of negative slope. 5. Ouabain, at concentrations which caused a comparable inhibition of Ip, exerted DHO-like effects on the Ip-V relationship of rat ventricular myocytes. However, the effects developed more slowly. 6. A slowly developing alteration of the Ip-V curve was also observed upon application of DHO to guinea-pig ventricular cells. The range of [DHO] used was about 100-fold lower than that applied to rat ventricular cells, but was equally effective for Ip inhibition. 7. Increasing the K+ concentration of DHO-containing media affected the existing equilibrium of DHO binding to the cardiac Na(+)-K+ pump. A new equilibrium was reached within about 3 s in rat ventricular myocytes, but only within about 50 s in guinea-pig ventricular cells under the experimental conditions chosen. 8. It is concluded that the changes of the cardiac Ip-V curve induced by cardiac glycosides are mediated by voltage-dependent variations of the local [K+]o at the K+ binding sites of the Na(+)-K+ pump in an 'access channel'. The variations were estimated by means of the Boltzmann equation. The estimations agreed with those derived from the measured DHO binding to the Na(+)-K+ pump at various [K+]o. A new equilibrium of glycoside binding to the pump is established at the altered [K+]o. The time necessary to reach the new binding equilibrium varies with the cardioactive steroid, its concentration and the glycoside sensitivity of the cardiac cells.