Pilot Study for the Tight K Study

Cardiac Arrythmias Clinical Trial

— TightK  

Official title:

PILOT STUDY for the Tight K TRIAL. Arrhythmias on the Cardiac Intensive Care Unit - Does Maintenance of High-normal Serum Potassium Levels Matter?

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT03195647
• Other study ID #: 011660
• Status: Completed
• Phase: Phase 3
• Start date: August 1, 2017
• Est. completion date: May 29, 2018

Study information

• Verified date: June 2018
• Source: Barts & The London NHS Trust
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

The primary purpose of this pilot study will be feasibility of recruitment. However, in order to further inform a full randomised controlled trial (RCT), information on the incidence of atrial fibrillation (AF) and other arrhythmias, hospital length of stay, resource use and morbidity will be collected.

Description:

Arrhythmias are common in critical care, with atrial tachyarrhythmias (and especially AF) being the most prevalent. This is especially true after cardiac surgery, with approximately 1 in 3 patients affected. The occurrence of new-onset post-operative AF is associated with increased short and long-term mortality, intensive care unit (ICU) and hospital stay and costs of care. This association appears causal, even after correction for confounding factors.

Potassium (K+) plays an important role in cardiac electrophysiology and abnormal levels may cause arrhythmias. Hypokalaemia, defined as a serum K+ <3.6 milliequivalents per litre (mEq/L) is thus associated with an increased incidence of ventricular arrhythmia after myocardial infarction. Low K+ levels are common following cardiac surgery, and appear marginally lower in those suffering atrial arrhythmias in this context. Despite an absence of proof that this association is causal, efforts to maintain serum [K+] in the 'high-normal' range (4.5 - 5.5 mEq/L) are considered 'routine practice' for AF prevention worldwide. The efficacy of such intervention remains unproven and data supporting this practice is extremely limited, being derived from observational rather than interventional studies. Indeed, no data exist to demonstrate that maintaining a high-normal potassium level is beneficial, or that aggressive replenishment of potassium in patients with heart disease necessarily leads to a better clinical outcome.

Furthermore, the method of potassium supplementation may be problematic. Oral replacement is not possible immediately post-operatively. Central venous administration is thus generally utilised in the early post-operative period. However, this practice is both time-consuming and costly: the intravenous administration of potassium carries recognised clinical risk, and is now prescribed in pre-diluted doses, stored securely for a safety purposes. Oral replacement is commonly associated with profound nausea, and is very poorly tolerated by patients. The investigators have estimated that the annual spending on potassium in cardiothoracic patients at Barts Health National Health Service (NHS) Trust is £100,000, compared to £16,500 for Milrinone (perceived as a high cost drug (2011-2012 prices). Additional costs relating to nursing time, drug checks, and intravenous connection and charting are also accrued. Central venous catheters may also be routinely left in situ solely for the purposes of parenteral potassium replacement; leading to an increased risk of line-related sepsis.

The routine maintenance of serum K+ in the high-normal range is thus a costly and unproven practice.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 160
• Est. completion date: May 29, 2018
• Est. primary completion date: April 24, 2018
• Accepts healthy volunteers: No
• Gender: All
• Age group: 18 Years and older

Eligibility

Inclusion Criteria:

1. All patients undergoing isolated elective coronary artery bypass graft (CABG)

Exclusion Criteria:

1. Age less than 18 years

2. Previous AF

3. Concurrent patient involvement in another clinical study assessing post-operative interventions

4. On-going infection/sepsis at the time of operation

5. Pre-op high-degree atrioventricular (AV) block

6. Pre-op serum K+ greater than 5.5 mEq/L

7. Current or previous use of medication for the purposes of cardiac rhythm management

8. Dialysis dependent end stage renal failure

Related Conditions & MeSH terms

• Arrhythmias, Cardiac
• Cardiac Arrythmias

Intervention

Drug:
• Potassium
The trial treatment will start when patients are admitted to the intensive care unit after their surgery. The patient will undergo regular blood investigations, as per current practice. The frequency of K+ monitoring while on ICU will be according to clinician / nursing staff preference. Potassium supplementation will be according to local hospital protocols. This can be either via an intravenous infusion or as a tablet. Patients will otherwise be treated as per current hospital protocol.

Locations

Country	Name	City	State
United Kingdom	Barts Health NHS Trust	London
United Kingdom	St George's University Hospital London	London

Sponsors (2)

Lead Sponsor	Collaborator
Barts & The London NHS Trust	London School of Hygiene and Tropical Medicine

Country where clinical trial is conducted

United Kingdom, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Total number of patients recruited over a 6 month period	The pilot study is being conducted to assess if it is feasible to recruit the required patient population into the study. The aim of the pilot is to recruit 160 patients over 6 months from two different centres.	6 months
Primary	Number of patients successfully randomised into the study to receive standard either usual care or control of potassium at the lower limit of the normal range	The pilot study will investigate if it is feasible to randomised patients between the control and intervention arms of the study	6 months
Primary	Protocol violation rate	Feasibility of ensuring that protocol violation rate is no more than 10%	6 months
Primary	Number of patient with outcome data at 28 days	This is a feasibility and one of the main outcome will be to assess the number of participants with outcome data at 28 days. The study will aim to follow up 90% of the patients randomised.	6 months
Secondary	Incidence of new onset atrial fibrillation	Episode of AF lasting at least 30 seconds that is clinically detected and/or electrocardiographically confirmed post surgery until day 5	Maximum of 5 days
Secondary	Mean critical care length of stay	Average time patients are treated on critical care ward	Maximum 28 days
Secondary	Mean hospital length of stay	Average time patients are inpatients in all hospital wards	Maximum 28 days
Secondary	Incidence of all other arrhythmias, defined using standard diagnostic criteria	All other arrhythmias detected clinically and/or review of holter monitor data	Maximum of 5 days
Secondary	Incidence of in-patient mortality	Number of patients deceased during their hospital stay	28 days from randomisation
Secondary	Incidence of mortality	All incidence of mortality during hospital stay and follow up	28 days from randomisation
Secondary	Cost-effectiveness		28 days from randomisation