Potassium Supplementation and Prevention of Atrial Fibrillation After Cardiac Surgery: The TIGHT K Randomized Clinical Trial

Benjamin O’Brien; Niall G. Campbell; Elizabeth Allen; Zahra Jamal; Joanna Sturgess; Julie Sanders; Charles Opondo; Neil Roberts; Jonathan Aron; Maria Rita Maccaroni; Richard Gould; Bilal H. Kirmani; Ben Gibbison; Gudrun Kunst; Alexander Zarbock; Maren Kleine-Brüggeney; Christian Stoppe; Keith Pearce; Mark Hughes; Laura Van Dyck; Richard Evans; Hugh E. Montgomery; Diana Elbourne; TIGHT K investigators

doi:10.1001/jama.2024.17888

Potassium Supplementation and Prevention of Atrial Fibrillation After Cardiac Surgery: The TIGHT K Randomized Clinical Trial

Benjamin O’Brien^*, Niall G. Campbell, Elizabeth Allen, Zahra Jamal, Joanna Sturgess, Julie Sanders, Charles Opondo, Neil Roberts, Jonathan Aron, Maria Rita Maccaroni, Richard Gould, Bilal H. Kirmani, Ben Gibbison, Gudrun Kunst, Alexander Zarbock, Maren Kleine-Brüggeney, Christian Stoppe, Keith Pearce, Mark Hughes, Laura Van DyckRichard Evans, Hugh E. Montgomery, Diana Elbourne, TIGHT K investigators

^*Corresponding author for this work

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Abstract

IMPORTANCE Supplementing potassium in an effort to maintain high-normal serum concentrations is a widespread strategy used to prevent atrial fibrillation after cardiac surgery (AFACS), but is not evidence-based, carries risks, and is costly. OBJECTIVE To determine whether a lower serum potassium concentration trigger for supplementation is noninferior to a high-normal trigger. DESIGN, SETTING, AND PARTICIPANTS This open-label, noninferiority, randomized clinical trial was conducted at 23 cardiac surgical centers in the United Kingdom and Germany. Between October 20, 2020, and November 16, 2023, patients with no history of atrial dysrhythmias scheduled for isolated coronary artery bypass grafting (CABG) surgery were enrolled. The last study patient was discharged from the hospital on December 11, 2023. INTERVENTIONS Patients were randomly assigned to a strategy of tight or relaxed potassium control (only supplementing if serum potassium concentration fell below 4.5 mEq/L or 3.6 mEq/L, respectively). Patients wore an ambulatory heart rhythm monitor, which was analyzed by a core laboratory masked to treatment assignment. MAIN OUTCOMES AND MEASURES The prespecified primary end point was clinically detected and electrocardiographically confirmed new-onset AFACS in the first 120 hours after CABG surgery or until hospital discharge, whichever occurred first. All primary outcome events were validated by an event validation committee, which was masked to treatment assignment. Noninferiority of relaxed potassium control was defined as a risk difference for new-onset AFACS with associated upper bound of a 1-sided 97.5% CI of less than 10%. Secondary outcomes included other heart rhythm-related events, clinical outcomes, and cost related to the intervention. RESULTS A total of 1690 patients (mean age, 65 years; 256 [15%] females) were randomized. The primary end point occurred in 26.2% of patients (n = 219) in the tight group and 27.8% of patients (n = 231) in the relaxed group, which is a risk difference of 1.7% (95% CI, −2.6% to 5.9%). There was no difference between the groups in the incidence of at least 1 AFACS episode detected by any means or by ambulatory heart rhythm monitor alone, non-AFACS dysrhythmias, in-patient mortality, or length of stay. Per-patient cost for purchasing and administering potassium was significantly lower in the relaxed group (mean difference, $111.89 [95% CI, $103.60-$120.19]; P < .001). CONCLUSIONS AND RELEVANCE For AFACS prophylaxis, supplementation only when serum potassium concentration fell below 3.6 mEq/L was noninferior to the current widespread practice of supplementing potassium to maintain a serum potassium concentration greater than or equal to 4.5 mEq/L. The lower threshold of supplementation was not associated with any increase in dysrhythmias or adverse clinical outcomes.

Original language	English
Pages (from-to)	979-988
Number of pages	10
Journal	JAMA
Volume	332
Issue number	12
DOIs	https://doi.org/10.1001/jama.2024.17888
Publication status	Published - 31 Aug 2024

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Tight K results accepted 16.08.24Accepted author manuscript, 416 KB

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O’Brien, B., Campbell, N. G., Allen, E., Jamal, Z., Sturgess, J., Sanders, J., Opondo, C., Roberts, N., Aron, J., Maccaroni, M. R., Gould, R., Kirmani, B. H., Gibbison, B., Kunst, G., Zarbock, A., Kleine-Brüggeney, M., Stoppe, C., Pearce, K., Hughes, M., ... TIGHT K investigators (2024). Potassium Supplementation and Prevention of Atrial Fibrillation After Cardiac Surgery: The TIGHT K Randomized Clinical Trial. JAMA, 332(12), 979-988. https://doi.org/10.1001/jama.2024.17888

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title = "Potassium Supplementation and Prevention of Atrial Fibrillation After Cardiac Surgery: The TIGHT K Randomized Clinical Trial",

abstract = "IMPORTANCE Supplementing potassium in an effort to maintain high-normal serum concentrations is a widespread strategy used to prevent atrial fibrillation after cardiac surgery (AFACS), but is not evidence-based, carries risks, and is costly. OBJECTIVE To determine whether a lower serum potassium concentration trigger for supplementation is noninferior to a high-normal trigger. DESIGN, SETTING, AND PARTICIPANTS This open-label, noninferiority, randomized clinical trial was conducted at 23 cardiac surgical centers in the United Kingdom and Germany. Between October 20, 2020, and November 16, 2023, patients with no history of atrial dysrhythmias scheduled for isolated coronary artery bypass grafting (CABG) surgery were enrolled. The last study patient was discharged from the hospital on December 11, 2023. INTERVENTIONS Patients were randomly assigned to a strategy of tight or relaxed potassium control (only supplementing if serum potassium concentration fell below 4.5 mEq/L or 3.6 mEq/L, respectively). Patients wore an ambulatory heart rhythm monitor, which was analyzed by a core laboratory masked to treatment assignment. MAIN OUTCOMES AND MEASURES The prespecified primary end point was clinically detected and electrocardiographically confirmed new-onset AFACS in the first 120 hours after CABG surgery or until hospital discharge, whichever occurred first. All primary outcome events were validated by an event validation committee, which was masked to treatment assignment. Noninferiority of relaxed potassium control was defined as a risk difference for new-onset AFACS with associated upper bound of a 1-sided 97.5% CI of less than 10%. Secondary outcomes included other heart rhythm-related events, clinical outcomes, and cost related to the intervention. RESULTS A total of 1690 patients (mean age, 65 years; 256 [15%] females) were randomized. The primary end point occurred in 26.2% of patients (n = 219) in the tight group and 27.8% of patients (n = 231) in the relaxed group, which is a risk difference of 1.7% (95% CI, −2.6% to 5.9%). There was no difference between the groups in the incidence of at least 1 AFACS episode detected by any means or by ambulatory heart rhythm monitor alone, non-AFACS dysrhythmias, in-patient mortality, or length of stay. Per-patient cost for purchasing and administering potassium was significantly lower in the relaxed group (mean difference, $111.89 [95% CI, $103.60-$120.19]; P < .001). CONCLUSIONS AND RELEVANCE For AFACS prophylaxis, supplementation only when serum potassium concentration fell below 3.6 mEq/L was noninferior to the current widespread practice of supplementing potassium to maintain a serum potassium concentration greater than or equal to 4.5 mEq/L. The lower threshold of supplementation was not associated with any increase in dysrhythmias or adverse clinical outcomes.",

author = "Benjamin O{\textquoteright}Brien and Campbell, {Niall G.} and Elizabeth Allen and Zahra Jamal and Joanna Sturgess and Julie Sanders and Charles Opondo and Neil Roberts and Jonathan Aron and Maccaroni, {Maria Rita} and Richard Gould and Kirmani, {Bilal H.} and Ben Gibbison and Gudrun Kunst and Alexander Zarbock and Maren Kleine-Br{\"u}ggeney and Christian Stoppe and Keith Pearce and Mark Hughes and {Van Dyck}, Laura and Richard Evans and Montgomery, {Hugh E.} and Diana Elbourne and {TIGHT K investigators}",

year = "2024",

month = aug,

day = "31",

doi = "10.1001/jama.2024.17888",

language = "English",

volume = "332",

pages = "979--988",

journal = "JAMA",

issn = "0098-7484",

publisher = "American Medical Association (AMA)",

number = "12",

}

O’Brien, B, Campbell, NG, Allen, E, Jamal, Z, Sturgess, J, Sanders, J, Opondo, C, Roberts, N, Aron, J, Maccaroni, MR, Gould, R, Kirmani, BH, Gibbison, B, Kunst, G, Zarbock, A, Kleine-Brüggeney, M, Stoppe, C, Pearce, K, Hughes, M, Van Dyck, L, Evans, R, Montgomery, HE, Elbourne, D & TIGHT K investigators 2024, 'Potassium Supplementation and Prevention of Atrial Fibrillation After Cardiac Surgery: The TIGHT K Randomized Clinical Trial', JAMA, vol. 332, no. 12, pp. 979-988. https://doi.org/10.1001/jama.2024.17888

TY - JOUR

T1 - Potassium Supplementation and Prevention of Atrial Fibrillation After Cardiac Surgery

T2 - The TIGHT K Randomized Clinical Trial

AU - O’Brien, Benjamin

AU - Campbell, Niall G.

AU - Allen, Elizabeth

AU - Jamal, Zahra

AU - Sturgess, Joanna

AU - Sanders, Julie

AU - Opondo, Charles

AU - Roberts, Neil

AU - Aron, Jonathan

AU - Maccaroni, Maria Rita

AU - Gould, Richard

AU - Kirmani, Bilal H.

AU - Gibbison, Ben

AU - Kunst, Gudrun

AU - Zarbock, Alexander

AU - Kleine-Brüggeney, Maren

AU - Stoppe, Christian

AU - Pearce, Keith

AU - Hughes, Mark

AU - Van Dyck, Laura

AU - Evans, Richard

AU - Montgomery, Hugh E.

AU - Elbourne, Diana

AU - TIGHT K investigators

PY - 2024/8/31

Y1 - 2024/8/31

N2 - IMPORTANCE Supplementing potassium in an effort to maintain high-normal serum concentrations is a widespread strategy used to prevent atrial fibrillation after cardiac surgery (AFACS), but is not evidence-based, carries risks, and is costly. OBJECTIVE To determine whether a lower serum potassium concentration trigger for supplementation is noninferior to a high-normal trigger. DESIGN, SETTING, AND PARTICIPANTS This open-label, noninferiority, randomized clinical trial was conducted at 23 cardiac surgical centers in the United Kingdom and Germany. Between October 20, 2020, and November 16, 2023, patients with no history of atrial dysrhythmias scheduled for isolated coronary artery bypass grafting (CABG) surgery were enrolled. The last study patient was discharged from the hospital on December 11, 2023. INTERVENTIONS Patients were randomly assigned to a strategy of tight or relaxed potassium control (only supplementing if serum potassium concentration fell below 4.5 mEq/L or 3.6 mEq/L, respectively). Patients wore an ambulatory heart rhythm monitor, which was analyzed by a core laboratory masked to treatment assignment. MAIN OUTCOMES AND MEASURES The prespecified primary end point was clinically detected and electrocardiographically confirmed new-onset AFACS in the first 120 hours after CABG surgery or until hospital discharge, whichever occurred first. All primary outcome events were validated by an event validation committee, which was masked to treatment assignment. Noninferiority of relaxed potassium control was defined as a risk difference for new-onset AFACS with associated upper bound of a 1-sided 97.5% CI of less than 10%. Secondary outcomes included other heart rhythm-related events, clinical outcomes, and cost related to the intervention. RESULTS A total of 1690 patients (mean age, 65 years; 256 [15%] females) were randomized. The primary end point occurred in 26.2% of patients (n = 219) in the tight group and 27.8% of patients (n = 231) in the relaxed group, which is a risk difference of 1.7% (95% CI, −2.6% to 5.9%). There was no difference between the groups in the incidence of at least 1 AFACS episode detected by any means or by ambulatory heart rhythm monitor alone, non-AFACS dysrhythmias, in-patient mortality, or length of stay. Per-patient cost for purchasing and administering potassium was significantly lower in the relaxed group (mean difference, $111.89 [95% CI, $103.60-$120.19]; P < .001). CONCLUSIONS AND RELEVANCE For AFACS prophylaxis, supplementation only when serum potassium concentration fell below 3.6 mEq/L was noninferior to the current widespread practice of supplementing potassium to maintain a serum potassium concentration greater than or equal to 4.5 mEq/L. The lower threshold of supplementation was not associated with any increase in dysrhythmias or adverse clinical outcomes.

AB - IMPORTANCE Supplementing potassium in an effort to maintain high-normal serum concentrations is a widespread strategy used to prevent atrial fibrillation after cardiac surgery (AFACS), but is not evidence-based, carries risks, and is costly. OBJECTIVE To determine whether a lower serum potassium concentration trigger for supplementation is noninferior to a high-normal trigger. DESIGN, SETTING, AND PARTICIPANTS This open-label, noninferiority, randomized clinical trial was conducted at 23 cardiac surgical centers in the United Kingdom and Germany. Between October 20, 2020, and November 16, 2023, patients with no history of atrial dysrhythmias scheduled for isolated coronary artery bypass grafting (CABG) surgery were enrolled. The last study patient was discharged from the hospital on December 11, 2023. INTERVENTIONS Patients were randomly assigned to a strategy of tight or relaxed potassium control (only supplementing if serum potassium concentration fell below 4.5 mEq/L or 3.6 mEq/L, respectively). Patients wore an ambulatory heart rhythm monitor, which was analyzed by a core laboratory masked to treatment assignment. MAIN OUTCOMES AND MEASURES The prespecified primary end point was clinically detected and electrocardiographically confirmed new-onset AFACS in the first 120 hours after CABG surgery or until hospital discharge, whichever occurred first. All primary outcome events were validated by an event validation committee, which was masked to treatment assignment. Noninferiority of relaxed potassium control was defined as a risk difference for new-onset AFACS with associated upper bound of a 1-sided 97.5% CI of less than 10%. Secondary outcomes included other heart rhythm-related events, clinical outcomes, and cost related to the intervention. RESULTS A total of 1690 patients (mean age, 65 years; 256 [15%] females) were randomized. The primary end point occurred in 26.2% of patients (n = 219) in the tight group and 27.8% of patients (n = 231) in the relaxed group, which is a risk difference of 1.7% (95% CI, −2.6% to 5.9%). There was no difference between the groups in the incidence of at least 1 AFACS episode detected by any means or by ambulatory heart rhythm monitor alone, non-AFACS dysrhythmias, in-patient mortality, or length of stay. Per-patient cost for purchasing and administering potassium was significantly lower in the relaxed group (mean difference, $111.89 [95% CI, $103.60-$120.19]; P < .001). CONCLUSIONS AND RELEVANCE For AFACS prophylaxis, supplementation only when serum potassium concentration fell below 3.6 mEq/L was noninferior to the current widespread practice of supplementing potassium to maintain a serum potassium concentration greater than or equal to 4.5 mEq/L. The lower threshold of supplementation was not associated with any increase in dysrhythmias or adverse clinical outcomes.

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U2 - 10.1001/jama.2024.17888

DO - 10.1001/jama.2024.17888

M3 - Article

SN - 0098-7484

VL - 332

SP - 979

EP - 988

JO - JAMA

JF - JAMA

IS - 12

ER -

Potassium Supplementation and Prevention of Atrial Fibrillation After Cardiac Surgery: The TIGHT K Randomized Clinical Trial

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