PR interval prolongation is significantly associated with aortic root abscess: An age‐ and gender‐matched study

Abstract Background Electrocardiographic abnormalities, such as PR interval prolongation, have been anecdotally reported in patients with aortic root abscess (ARA). An electrocardiographic marker may be useful in identifying those patients with aortic valve endocarditis who may progress to ARA. The objective of this study is to evaluate the change in the PR interval in patients with surgically confirmed ARA and compare it to age‐ and gender‐matched controls with echocardiographically or surgically confirmed aortic valve endocarditis but without aortic root abscess and those hospitalized with diagnoses other than endocarditis. Methods Patients were eligible for enrollment if they were 18 years or older and were hospitalized for either ARA, aortic valve endocarditis, or for unrelated reasons and had at least one 12‐lead electrocardiogram (ECG) prior to or on the day of hospitalization and at least one ECG after hospitalization but prior to any cardiac surgical procedure. Delta PR interval, defined as the difference between the pre‐ and post‐admission PR interval, was the primary outcome of interest. The patients in the ARA group were age‐ and gender‐matched to patients with aortic valve endocarditis and to those without endocarditis. Comparisons of demographic variables and study outcomes were performed. Results Eighteen patients with surgically confirmed ARA were enrolled. These patients were age‐ and gender‐matched to 19 patients with aortic valve endocarditis and 18 patients with no past history or evidence of endocarditis during hospitalization. No difference was noted in the baseline PR interval between the groups. However, the PR interval following admission in the aortic root abscess group (201 ± 66 ms) was significantly longer than the PR interval in both the aortic valve endocarditis (162 ± 27 ms) (24%, p = .009) and no endocarditis (143 ± 24 ms) (40%, p < .001) groups. The primary outcome measure, delta PR interval, was significantly longer in the ARA group (35 ± 51 ms) than no endocarditis (−5 ± 17 ms) (p = .001) and aortic valve endocarditis groups (0.2 ± 18) (p = .003). Conclusions The findings of our study support the notion that the PR interval is more likely to be prolonged in patients with ARA. Since ARA is associated with a high morbidity and mortality, PR interval prolongation in a patient with aortic valve endocarditis should prompt a thorough evaluation for aortic root involvement.


Conclusions:
The findings of our study support the notion that the PR interval is morelikelytobeprolongedinpatientswithARA.SinceARAisassociatedwithahigh morbidityandmortality,PRintervalprolongationinapatientwithaorticvalveendocarditis should prompt a thorough evaluation for aortic root involvement.

| INTRODUC TI ON
Aorticrootabscess(ARA),whichoccursinapproximately20%of patients with aortic valve endocarditis, is associated with a high morbidity and mortality (John et al., 1991;Leontyev et al., 2016;Yangetal.,2020).TheriskofdevelopingARAishigherinpatients with aortic paravalvular leaks, mechanical aortic prostheses, aorticvalvevegetations,andculturenegativeendocarditis (Mahmoud etal.,2020).Electrocardiographically,new-onsethigh-gradeatrioventricular block has also been associated with a greater likelihood of aortic root involvement in patients with endocarditis (Arnett & Roberts, 1976;Graupner et al., 2002). The mechanistic basis of this finding lies in the close proximity of the cardiac conduction system to the periaortic region. Anecdotal case reports of PR interval prolongation in a handful of patients with ARA (Jain et al., 2015;Kariyanna et al., 2020;Lammers & Dantzig, 2005;Landa et al., 2018) have lent credence to the notion that more subtle conduction abnormalities like PR interval prolongation in patients with aortic valve endocarditis could indicate aortic root involvement.Thishypothesis,however,hasneverbeensystematically evaluated. The objective of this study is to evaluate the PR intervalrecordedon12-leadelectrocardiograms(ECGs)inpatients withsurgicallyconfirmedARAandcompareittoage-andgendermatchedcontrolswithechocardiographically(transesophageal)or surgically confirmed aortic valve endocarditis but without aortic root abscess and those hospitalized with diagnoses other that endocarditis or aortic valve disease.

| Study subjects
The study complied with the Declaration of Helsinki and the

| Definitions
Aortic Root Abscess Group: Subjects were included in this group if they met the modified Duke criteria (Nishimura et al., 2014) for diagnosis of de-novo endocarditis, had surgically confirmed aortic rootabscess,andhadatleastoneelectrocardiogrampriortooron thedayofadmission,andatleastoneelectrocardiogramfollowing admission but prior to any cardiac surgical procedure.

| Measurements
Measurements were performed using electronic calipers in Muse

TA B L E 1
Characteristics of the study patients endocarditis without aortic root involvement and those without a diagnosis of endocarditis. The main finding of this study is that the patients with ARA show a greater prolongation in the PR interval than patients with aortic valve endocarditis.
These findings imply that in patients with aortic valve endocarditis, prolongation of PR interval could be indicative of aortic root involvement and should prompt a thorough evaluation for the same.ThetimelydiagnosisofARAiscrucialtoreducingmorbidity and mortality and continues to remain a challenge. Transesophageal echocardiography (TEE) has been shown to be more sensitive than transthoracic echocardiography (TTE) and its utilization early duringthecourseoftheillnesscanhelphastenthediagnosis (Leung etal.,1994).ArecentstudyshowedECG-gatedCTtohavesimilar sensitivity to TEE suggesting its role in situations where TEE is contraindicatedornotavailable(Yeetal.,2020).
The location of the AV node in human hearts is variable.
Approximately 50% of humans have a predominantly right-sided AV node, 30% have a left-sided orientation, and the remaining 20% have an AV node running under the membranous septum just below the endocardium. The latter two anatomic variants are thought to predispose patients to increased risk of conduction abnormalities following transcatheter aortic valve replacement (Judson et al., 2019;Kawashima & Sato, 2014 analysis for known confounders such as age and gender by matching.
However,thepossibilityofconfounderswhichmayhavebeenpresent but were not adjusted for cannot be eliminated.
In conclusion, the findings of our study support the notion that the PR interval is more likely to be prolonged in patients withARAversusthosewithaorticvalveendocarditisalone.Since aortic root abscess is associated with a high morbidity and mortality,PRintervalprolongationinapatientwithaorticvalveendocarditis should prompt a thorough evaluation for aortic root involvement.

CO N FLI C T O F I NTE R E S T
None.

AUTH O R CO NTR I B UTI O N S
Drs.KohliandObuobiwereresponsibleforcollectingthedata.Drs.

E TH I C A L A PPROVA L
ThestudyconformstotheUSFederalpolicyforprotectionofhuman subjects and the study complied with the Declaration of Helsinki and theInstitutionalReviewBoardoftheUniversityofChicagoMedical Center approved this retrospective study. The need for informed consent was waived for this study.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are available from the corresponding author upon reasonable request.