1 Sub-chief of Electrophysiology, Centro Médico ABC (American British Cowdray). 2 Electrophysiology resident, Instituto Nacional de Cardiología Ignacio Chávez.
Corresponding author’s address
Dr. Manlio F. Márquez-Murillo
Postal address: Sur 136Nº 116, Col. Las Américas, Álvaro Obregón, 01120, Ciudad de México.
E-mail
Received on July 25, 2022 Accepted after review on July 26, 2022 www.revistafac.org.ar
There are no conflicts of interest to disclose.
Keywords:
Atrial fibrillation.
acute myocardial infarction
Morbi-mortality
In the study published in this issue of the Revista, titled “Clinical Characteristics, Treatment and Complications of Patients with Acute Myocardial Infarction and Atrial Fibrillation”, cases belonging to the ARGEN-IAM-ST registry, diagnosed with atrial fibrillation (AF), were analyzed[1,2]. It is very important to highlight that the ARGEN-IAM-ST is a national, prospective, observational and multicenter registry, unique in the Argentine population. From 5,708 cases of ST-elevation myocardial infarction (STEMI), 323 were identified as having AF, representing 5.7% of the total. The aim was to analyze the impact of AF on these patients with AMI, as well as describing their different characteristics and risk factors. It was found, as expected, that patients with AF were older and had more comorbidities (such as systemic hypertension and history of previous ischemic heart disease). Moreover, it was verified that the coexistence of both conditions leads to a significant increase in adverse cardiovascular events. Thus, there was a greater rate of strokes, which occurred in 3.1% of the group with AF, in comparison with just 0.8% of patients without this arrhythmia. Finally, it is very important to mention the great impact of AF on in-hospital mortality, which was 22.9% in those with AF in regard to 7.8% for those without AF.
The findings of this subanalysis of the ARGEN-IAM-ST registry were extremely interesting, since it underscores the great weight of AF as a risk factor for the appearance of adverse events in a population in very high cardiovascular risk such as patients with STEMI[3]. From the pathophysiological point of view, it makes sense that the increase in one of the main determinants of myocardial oxygen consumption, such as heart rate, would contribute to a worse prognosis in these patients[4]. Besides, we should highlight that the inflammatory state linked to AF has been associated to a grater platelet reactivity and activity at the atherosclerotic plaque level, which originates a risk of adverse events during the hospitalization of these patients[5]. Likewise, we should mention that the individuals that displayed this arrhythmia present more comorbidities such as hypertension and previous ischemic heart disease. Both are characteristics that increase risk in the case of AMI[6]. Of course, the fact that these patients are older also has an impact on the clinical outcome[7].
Likewise, another factor to consider in this population of patients is the implementation of the triple therapy (anticoagulation plus dual antiplatelet therapy). Thus, in this group of patients with STEMI plus de novo AF there was a substantial increase in the rate of bleeding, compared with patients who did not present AF. It would be interesting to observe which is the clear clinical benefit from this “triple therapy” in these patients in high risk of bleeding due to age and comorbidities, even considering their degree of “frailty”[4]. Furthermore, it is interesting to see the benefit of the triple therapy in the Latin American population, whether by using vitamin K antagonists or direct oral anticoagulants combined with antiplatelet agents. Currently, the guidelines for the diagnosis and treatment of AF published by the European Society of Cardiology recommend using the triple therapy for a week after the episode of STEMI. This duration is “short” as long as thrombotic risk is low. In the case the risk of stent thrombolysis is high, it is recommended to prolong this therapy for up to a month, and subsequently to continue with dual therapy with anticoagulation plus a single antiplatelet agent, for 12 months[8]. These analyses are necessary in the Latin American population, to issue guidelines according to the data from our population, who are known to present characteristics different from the Anglo-Saxon population[4].
The results of this analysis of the ARGEN-IAM-ST match what has been observed in other regions of the world. For instance, at the Instituto Nacional de Cardiología, 6,705 consecutive patients were analyzed, with Acute Coronary Syndrome, admitted to the Coronary Care Unit (CCU), including 3,094 with STEMI and 3,611 with NSTEMI[9]. AF was documented in 360 patients, representing 5.4%, a figure very similar to that of the registry published in this issue. We identified the patients that had preexistent AF (2.1%, n=140), those with new onset AF on admission (3.2%, n=220), and those that developed AF during their stay in the CCU (1.9%, n=127). Just as in this Argentine study, Mexican patients with AF presented clinical characteristics of high risk and developed a greater number of adverse events than patients without AF. The non-adjusted risk of in-hospital mortality was significantly higher in patients with preexistent AF and AF developed during CCU stay. However, after adjusting by multivariate analysis, only AF developed in the CCU and in the NSTEMI group there was an association a 4.4-fold increase in in-hospital mortality risk. This indicates that not all AF in a scenario of AMI is the same, and it is necessary to differentiate whether AF was preexistent or de novo .
Based on the results of this analysis of the ARGEN-IAM-ST registry, the appearance of AF both during acute clinical symptoms of STEMI and during the hospital stay does indeed have a vitally important connotation for the evolution of these patients, since it was associated to more in-hospital mortality and major cardiovascular events. It is for this reason that we should continue studying the impact of this arrhythmia on the Latin American population, as there are a few registries that study this topic. The information from the ARGEN-IAM-ST registry will surely be useful to design risk stratification and treatment strategies in a scenario of AMI in different populations, as in this case with AF.
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