In a patient presenting with presumably new-onset, symptomatic AF, urgent electrical cardioversion is not mandatory when hemodynamic impairment (i.e., myocardial ischemia, heart failure, symptomatic arterial hypotension, or cardiogenic shock) is not present [1]. In the presence, however, of disabling symptoms, that is, class III of the European Heart Rhythm Association (EHRA) classification (Table 8.2), pharmacological control of the rate of ventricular response of AF is advised [1].

Immediately next, decision is to be taken regarding the indication for oral anticoagulation (OAC). In this regard, stratification of the risk of stroke associated with AF needs to be carried out, preferably by using the validated CHA₂DS₂-VASc score [1] (Table 8.3). According to available evidence and current guidelines, for a CHA₂DS₂-VASc score ≥ 2, OAC is indicated unless a prohibitive risk of bleeding is present [1]. AF pattern, that is, paroxysmal, persistent, long-standing persistent, and permanent (Fig. 8.5), should not impact on the decision to prescribe OAC, given the reported comparable risk of stroke of the different types of AF [1]. To properly manage OAC during follow-up, stratification of the risk of bleeding associated with OAC should be performed [1]. Among the several scores which have been proposed, the HAS-BLED score has been shown to be the most predictive of major bleeding complications while also being very much user-friendly (Table 8.4) [1]. The presence of a high risk of major bleeding, as identified by a HAS-BLED score ≥ 3, however, should not lead per se to withhold OAC while mandating instead attention and careful management of the correctable factors associated with increased risk of bleeding as well as careful and close patient monitoring during follow-up [2].

While continuation of antiplatelet therapy with aspirin only might be considered in a patient with new-onset AF and remote (i.e., > 1 year) implantation of either bare-metal (BMS) or drug-eluting (DES) coronary stent when the CHA₂DS₂-VASc score is 1 (i.e., male patient with vascular disease as the only risk factor for stroke), in the remaining categories of stroke risk, that is, CHA₂DS₂-VASc score ≥ 2 (likely also including female patient with vascular disease as the only risk factor for stroke), the question is whether or not aspirin should be continued together with OAC. In accordance with available evidence and current guidelines, OAC monotherapy should be prescribed to patients with stable coronary artery disease (defined as ≥ 1 year without recurrent events after an acute coronary syndrome and/or PCI and/or coronary bypass graft surgery) developing AF (Table 8.5) [1, 3, 4]. Combining aspirin to OAC (with vitamin K antagonists (VKAs)) in this context, in fact, appears not to bring additional benefit compared to OAC alone with respect to the prevention of stroke and recurrent cardiac events [5]. On the contrary, the risk of bleeding associated with the combination of OAC (with VKAs) and aspirin is substantially increased in comparison to monotherapy with either of the two drugs [5, 6]. Therefore, routine combination of OAC and aspirin in patient with stable coronary artery disease developing AF is discouraged while possibly being considered only in selected cases at low bleeding risk in whom stent thrombosis and/or recurrent cardiac event may have catastrophic consequences (such as previous stenting of the left main or last remaining vessel or recurrent cardiac events, especially in patients with diabetes) (Table 8.5) [1, 3, 4]. The type of stent, that is, BMS or (new-generation) DES (Table 8.1), previously implanted, should generally not to impact on the choice to combine or not aspirin and OAC because the incidence of very late (i.e., > 12 months after implantation) stent thrombosis (Table 8.6) appears limited (i.e., in the range of approximately 0.5 % per year) and comparable with the two types of stent [7].