Author`s Reply.

To the Editor,

First, we would like to thank the author(s) for their interest and valuable contribution to our research. Both studies were designed in a similar manner (1, 2). The studied populations were both ST-elevation myocardial infarction patients who had undergone primary percutaneous coronary intervention (1, 2). Both studies were retrospective in nature (1, 2). Apart from our study, Keskin et al. (2) conducted a study on a larger population and evaluated the mean serum potassium (sK) level rather than the admission sK level. Moreover, they differently categorized patients in terms of mean sK level (<3.0, 3.0–<3.5, 3.5–<4.0, 4.0–<4.5, 4.5–<5.0, 5.0–<5.5, and ≥5.5 mmol/L) (2). In our study, we categorized patients based on the admission sK level as <3.5, 3.5–<4, 4–<4.5, 4.5–<5, and ≥5 mmol/L (1).

The main finding of our study was the relation between admission sK level of >4.5 mmol/L and increased long-term mortality (1). The current guidelines recommend sK level of 4.0–5.0 mmol/L in patients with acute myocardial infarction (3). The results of recently undertaken studies and those of Keskin et al.’s study (2) were in accordance with our study (4). Moreover, we showed that the lowest mortality was associated with sK levels of 3.5–<4 mmol/L, which is similar to the findings by Choi et al.’s study (4). Keskin et al. (2) showed that the optimal sK level was 3.5–4.5 mmol/L, with the lowest mortality being associated with sK levels of 4.0–4.5 mmol/L. Another similar finding was the association between ventricular arrhythmias and sK level. Both studies showed that ventricular arrhythmias were associated with sK level of <3 mmol/L (1, 2). In addition, in our study, we also found that admission sK level of ≥5 mmol/L is associated with ventricular arrhythmias (1).

The recommended level of sK was done in rather an early time (3). Over time, following the release of the guidelines, various drugs and revascularization techniques and strategies have been developed. The combined findings from retrospective studies have pointed out that the most favorable clinical outcomes occurred with sK level between 3.5–4.5 mmol/L in acute myocardial infarction (1, 2, 4). In order to prevent ventricular arrhythmias, the same sK level should be maintained. Even though various retrospective studies demonstrated similar clinical end points, prospective studies are needed for strong advisement.