In emergency medicine we know that cardiac events have a circadian pattern, more in the morning.
So here is a study that shows that in a medicated and monitored group with implanted defibrillators, the morning problem and the Monday problem disappears.
As an aside–you awaken with chest pain, you come see me or your nearest emergency department if you are a person at risk for heart disease–adult men past 40 are at risk for sho’.
TAKE-HOME MESSAGE
In this substudy of the SCD-HeFT trial, data on patients with systolic heart failure who were randomly assigned to ICD implantation were reviewed for timing of ICD therapies. Overall, appropriate ICD therapies did not appear to occur more frequently in the early morning (12 am to 6 am) nor on Mondays. However, patients not on beta-blocker therapy did have more frequent early morning events.
Circadian patterns of neurohormonal triggers may play a role in ventricular arrhythmia in heart failure patients.
– Ashish Aggarwal, MD
ABSTRACT
OBJECTIVES
We sought to determine whether circadian patterns in ventricular arrhythmias occur in a current primary prevention defibrillator (ICD) population.
BACKGROUND
Cardiovascular events, including ventricular arrhythmias, demonstrate biorhythmic periodicity.
METHODS
We tested for deviation from the previously described occurrences of a morning peak, early morning nadir and Monday peak in ICD therapies using generalized estimating equations and t-tests. All hypothesis tests were carried out in the entire cohort of patients with ventricular arrhythmias as well as prespecified subgroups.
RESULTS
Of 811 ICD patients, 186 subjects received 714 ICD therapy episodes for life-threatening VA. There was no morning (6 a.m. to 12 noon) peak in therapies for the entire cohort nor in any subgroups. The overall cohort, and several subgroups had a typical early morning (12 midnight to 6 a.m.) nadir in therapies, with significantly less than 25% of therapies occurring during this 6-hour block (all p<0.05). A significant Monday peak in therapies occurred only in patients not on beta blocker (22% of events for the week, p=0.029).
CONCLUSIONS
In the SCD-HeFT population, the distribution of life threatening VA failed to demonstrate a typical early morning peak or increased VA events on Mondays. A typical early a.m. nadir was seen in the entire cohort. An increased rate of events on Mondays in the subgroup of subjects not on beta-blockade was found. These findings may indicate suppression of the neurohormonal triggers for ventricular arrhythmia by current heart failure therapy, particularly the use of beta-blockers in heart failure.
Journal of the American College of Cardiology
Unexpected Deviation in Circadian Variation of Ventricular Arrhythmias in the Sudden Cardiac Death in Heart Failure Trial
J Am Coll Cardiol 2014 Apr 16;[EPub Ahead of Print], KK Patton, AS Hellkamp, KL Lee, DB Mark, GW Johnson; J Anderson, GH Bardy, JE Poole
This abstract is available on the publisher's site.