The leading cause of morbidity and mortality in patients with chronic kidney disease (CKD) is cardiovascular disease. Patients with CKD are also at increased risk of cardiac rhythm abnormalities including atrial fibrillation and ventricular arrhythmias compared with the general population. Cardiac rhythm abnormalities lead to poor clinical outcomes, including higher rates of death and sudden cardiac death. Identification of preclinical cardiac arrhythmias may provide opportunities for early therapy to improve the poor outcomes in patients with CKD.
Nazem Akoum, MD, and colleagues recently conducted a prospective observational study utilizing mobile cardiac telemetry monitors to study the rate of cardiac rhythm abnormalities. The study cohort included patients with moderate-to-severe CKD (estimated glomerular filtration rate 15 to 60 mL/min/1.73 m2 not requiring dialysis) and type 2 diabetes. The researchers sought to test the hypothesis that, as in the dialysis population, rates of preclinical cardiac arrhythmias would be high in the study cohort. Results were reported in the Clinical Journal of the American Society of Nephrology [2019;14(4):549-556]
The observational study CANDY (Continuous Glucose Monitoring to Assess Glycemia in CKD) was conducted at the University of Washington. Participants were patients with type 2 diabetes mellitus and CKD. The arrhythmia study was a substudy of the CANDY study. Patients were offered mobile cardiac telemetry monitoring with the SEEQ device (SEEQ; Medtronic, Inc., Minneapolis, Minnesota) for a minimum of 7 days and up to 28 days. The SEEQ monitor is a patch that attaches to the patient’s pectoral area and provides a single-lead electrocardiogram recording.
Of the 81 patients with CKD in the CANDY study, 68 were approached to participate in the substudy. Of those, 56% (n=38) agreed to wear the SEEQ device and participate in the arrhythmia study, with no loss to follow-up.
Of the 38 patients who agreed to participate, 50% (n=19) wore the SEEQ device for one monitoring period (mean, 13 days), 47% (n=18) for two monitoring periods (mean 14.1 days), and 3% (n=1) for three monitoring periods (22 days). Mean duration of overall monitoring per patient was 11.2 days.
Mean age of study participants was 68 years, 66% were men, and 84% were white. A total of 39% had a history of cardiovascular disease; heart failure was the most common type of cardiovascular disease. Seventy-one percent were obese, and mean estimated glomerular filtration rate was 38 mL/min/1.73 m2. Ninety-two percent were taking antihypertensive medications: 76% were taking angiotensin-converting enzyme inhibitors/angiotensin receptor blockers and 55% were taking beta-blockers. Eighty-nine percent were on insulin, either alone or in combination with another oral hypoglycemic. Eleven percent were also taking thyroid supplementation.
Among the 38 substudy participants, 18 unique participants (47%) experienced 104 arrhythmic episodes. The overall rate of any cardiac arrhythmic episode in patients with CKD was 88.8 (95% confidence interval, 27.1-184.6) episodes per person-year. Atrial fibrillation and conduction abnormalities occurred at the highest rates.
The rate of occurrence of conduction abnormalities was 26.5 per person-year (31 episodes among eight individuals). Second-degree atrioventricular block had the most episodes, but was limited to one participant. Compared with other cardiac arrhythmias, the lowest rate was seen in ventricular arrhythmias: there were 17 episodes of ventricular arrhythmias in nine unique individuals (24%). Premature ventricular complexes were the most common types of ventricular arrhythmias.
There were significant associations between age ≥65 years, body mass index ≥30 kg/m2, use of beta-blocker/non-dihydropyridine (DHP) calcium channel blocker, and prior history of cardiovascular disease (coronary disease, heart failure, or stroke) and greater rates of cardiac arrhythmias of any type.
Seven of the 38 participants had a previous diagnosis of atrial fibrillation (AF); of the remaining 31 participants, four (13%) received a new diagnosis of AF. Overall, there were 44 individual episodes of AF with a rate of 37.6 per person-year. There were no symptoms reported during any of the 44 AF episodes, and the duration of most of the episodes was between 5 minutes and 1 hour (59%), followed by 1 to 6 hours (38%) and >6 hours (2.7%).
Of the total cohort of 38 participants, 15 had known cardiovascular disease. Compared with the 23 patients without known cardiovascular disease, there appeared to be a trend toward higher rates of any arrhythmia overall and by subtype in the 15 participants with known cardiovascular disease. There also seemed to be a trend for a large variation in rate of AF and conduction abnormalities between the group with known cardiovascular disease and the group without known cardiovascular disease. Due to limited power, those analyses were exploratory.
Twenty-three participants (61%) were taking either beta-blockers or non-DHP calcium channel blockers. In analyses stratified by use of those agents, there appeared to be a trend toward higher rates of all arrhythmia types in the group taking either agent. The variation between the group taking the agents and the group not taking the agents appeared largest for risk of AF and conduction abnormalities.
The small sample size was among the limitations cited by the researchers. Others were only including participants with type 2 diabetes, lack of data on long-term outcomes, and lack of a control group.
The researchers said, “In conclusion, in this study of participants with moderate CKD and type 2 diabetes, we found subclinical cardiac arrhythmias to be common, as nearly half of the participants experienced cardiac arrhythmias detected by mobile cardiac telemetry. Subclinical cardiac arrhythmias may be important precursors to clinically significant cardiovascular events, including sudden cardiac death. Further data are needed to determine whether treatment of subclinical cardiac arrhythmias reduce cardiovascular complications and improve overall survival in this high-risk CKD population.”
Takeaway Points
- Researchers conducted a prospective observational study in patients with chronic kidney disease (CKD) and type 2 diabetes to determine the rate of atrial and ventricular arrhythmias, as well as conduction abnormalities in that patient population.
- In a sample of 38 participants of the CANDY study, the overall mean rate of any cardiac arrhythmia was 88.8 episodes per person-year. Participants with a history of cardiovascular disease had a higher rate of detected arrhythmia.
- In patients with moderate CKD and type 2 diabetes, cardiac rhythm abnormalities were common; rates of atrial fibrillation were high and the episodes were asymptomatic.
Cardiac Rhythm Abnormalities
