Linde-Edelstam et al. demonstrated that the importance of atrial contraction to ventricular filling diminishes in accordance with increasing blood flow velocity as the exercise work load increases . Furthermore, left atrial pressure determines the contribution of atrial contraction to LV filling, and the elevation of pulmonary capillary wedge pressure was reported to diminish the power of atrial contraction on the cardiac output . These studies suggest that multiple factors affect the contribution of atrial-derived factors on the cardiac output. Further investigations should be conducted to better understand the mechanism underlying decreased O_dos pulse in AF patients.

Another interesting aspect of this manuscript is the close association between the HR response and increase in the O₂ pulse above the AT level. The inverse association between HR change, which is a marker of chronotropy, and the increase in the O₂ pulse above the AT level is strikingly enhanced in AF patients. The HR change during exercise could predict the trend of the O₂ pulse at the submaximal stage. In addition, there were two different groups with different trends in the O₂ pulse in AF patients; one wherein VO₂ is maintained above the AT level by increasing HR and one wherein VO₂ is maintained by increasing the stroke volume. The blunted increase in the O₂ pulse above the AT level corresponded to the enhanced response of chronotropy, maintaining the value of VO₂/kg. However, there were no differences in laboratory data, echocardiographic parameters, and medication profiles.

Several studies have demonstrated the newest association between Time otherwise Hours response and practice capabilities [21,22]. The newest improved Hour reaction during the AF clients might have been shown for the previous studies [fourteen,23] possesses come considered on account of a greater sympathetic drive triggered to maintain cardiac yields. Although not, increasing Time cannot always raise do it tolerance or symptoms in the AF patients . In reality, the degree of overstated chronotropic effect evoked a negative influence on cardiac output over the average concentration of do it and also the unfavorable perception is significantly more enhanced from inside the AF people. Contained in this research, there’s zero factor inside Hr pattern ranging from AF and you may cSR people, that may have demostrated the many organization of Hour impulse plus the change off cardiac productivity between AF and you can cSR people in more advanced level trends. The newest determinant situations out of chronotropy within the AF clients got justified far more concisely [twenty-five,26]. Several other you can easily determining foundation from chronotropy for the AF is atrial mode, such as for instance atrial appendage emptying acceleration otherwise atrial contractile function. So you can make sure they, more intricate comparison off atrial means are going to be performed.

However, the connection anywhere between get it done capacity and you can Hr answer is more complicated inside the AF customers

The findings of the current study suggested that, aerobic exercise is generally performed as a main protocol of cardiac rehabilitation, in which the change of O₂ pulse during exercise had similar behavior between patients with sinus rhythm and AF. However, the exercise capacity is significantly impaired above the level of AT and the change of HR reflected the burden of exercise in a more exaggerated manner in patients with AF than patients with sinus rhythm.

5. Investigation restrictions

There are several limitations in the present study, which includes a small study population without healthy controls. In addition, the patient population was limited to those receiving cardiac rehabilitation http://www.datingranking.net/pl/latinomeetup-recenzja/, which could evoke referral bias because patients referred for cardiac rehabilitation are not representative of the general community population. In selecting cSR patients, there was some possibility that they were different from SR patients and the difference of chronotropic competency may be a candidate to segregate the cSR group from a general SR group, which, however, is above the scope of this study. The elucidation of basic characteristics of these classifications is also warranted. Because the disease severity in our patients was mild and the study population included only Japanese patients, the results should be carefully interpreted when applied to different populations. The voluntary participation of the study patients in ambulatory cardiac rehabilitation may introduce some bias in the present study. In addition, the study design was limited regarding the evaluation of the effect of medications. Among them, the medication of beta blockers should be carefully considered because it might significantly affect the behavior of HR. However, there were no significant differences in HR trend, VO₂/kg trend during exercise in AF patients in this study.