Sex differences in echocardiographic predictors of bradycardia detected by implantable loop recorder in patients with syncope and palpitations.

OBJECTIVE: Our aim was to investigate whether echocardiography may aid in identifying patients, specifically men, at risk of bradycardia as detected by implantable loop recorders (ILR) in patients evaluated for syncope and palpitations. METHODS: We included ambulatory patients undergoing ILR implantation for syncope (84%), presyncope (9%), and palpitations (8%). Echocardiographic examination was performed prior to implantation (2.9 months [IQR 1.0-6.0 months]). Echocardiograms were analyzed for conventional and speckle tracking parameters. We examined time to first event of bradycardia, defined as (a) heart rate <30 beats/min and (b) ≥4 beats, including sinus arrest, asystole, sinoatrial block, and second- and third-degree atrioventricular nodal block. We applied Cox proportional hazards models. RESULTS: A total of 285 patients we enrolled, and during a median time of 2.7 years [IQR 1.0, 3.3 years] of continuous heart rhythm monitoring, 84 (29%) had bradycardia detected by ILR. Patients with bradycardia were older (61 ± 19 years vs 55 ± 18 years, P = .01) and more frequently men (62% vs 44%, P = .01). Sex modified the association between echocardiographic parameters and bradycardia (P interaction <0.05 for all), such that left ventricular LV mass index (HR: 1.02 per 1g/m2 increase [1.01-1.04], P < .001), LV ejection fraction (HR: 1.04 per 1% decrease [1.01-1.08], P = .02), and global longitudinal strain (HR: 1.09 per 1% decrease [1.01-1.19], P = .03) were associated with bradycardia in men but not women (P > .05 for all in female). After adjusting for baseline clinical characteristics, medical therapy, and loop indication, the abovementioned parameters remained significantly associated with incident bradycardia in men. CONCLUSION: Echocardiographic parameters of LV structure and function may potentially be more useful for predicting bradycardia in men than women, among patients undergoing ILR implantation for syncope, presyncope, and palpations.

Usefulness of echocardiography for predicting ventricular tachycardia detected by implantable loop recorder in syncope patients.

Ventricular tachycardia (VT) may lead to syncope and sudden cardiac death. Implantable loop recorders (ILR) are recommended in the clinical work-up of patients with unexplained syncope. Our aim was to evaluate if echocardiographic parameters assessed prior to ILR implantation in patients with unexplained syncope may aid in identifying individuals with an increased risk of VT. The present study included 288 ambulatory patients (mean age 58 ± 19 years, 51% women) with syncope (90%) and presyncope (10%) who had an ILR implanted in the diagnostic workup. All patients underwent an echocardiographic examination prior to device implantation (median 3 months [IQR 1 to 6 months]). We examined incident VT, defined as a first-time episode of VT (> 30 s) or non-sustained VT (< 30 s) detected by the ILR. During median follow-up of 2.9 years [IQR 1.3 to 3.5 years] of continuous rhythm monitoring, 36 patients (13%) were diagnosed with incident VT (n = 25 non-sustained VT, n = 11 sustained VT). In unadjusted Cox proportional hazards models, left ventricular (LV) mass index (HR: 1.04 per 1 g/m2 increase [1.00 to 1.08], P = 0.047), mean LV wall thickness (HR: 1.36 per 1 mm increase [1.08 to 1.71], P = 0.009), and global longitudinal strain (HR: 1.15 per 1% decrease [1.05 to 1.25], P = 0.002) were significantly associated with VT. After adjusting for age, sex, implantable loop recorder indication and known heart failure, the above-mentioned parameters remained significantly associated with incident VT. LV mass index, LV wall thickness, and GLS may aid in identifying patients with increased risk of incident VT among patients with syncope. Echocardiography may potentially help select patients who can benefit from ILR.

The prognostic value of left atrial dyssynchrony measured by speckle tracking echocardiography in the general population.

LA dyssynchrony is a predictor of cardiovascular morbidity in various patient populations. However, the prognostic value of LA dyssynchrony as evaluated by two-dimensional speckle tracking (2D-STE) in the general population is unknown. A cohort of 375 participants without atrial fibrillation (AF), ischemic heart disease (IHD), heart failure (HF) or previous ischemic stroke (IS) had an echocardiogram, including LA 2D-STE, performed. LA dyssynchrony was defined as the standard deviation of the time to peak regional LA reservoir strain values. The endpoints were all-cause mortality, a combined endpoint of AF and IS, and a combined endpoint of major adverse cardiovascular events (MACE) comprised of acute myocardial infarction (AMI), HF or cardiovascular death (CVD). During a median follow up of 16.1 years (IQR 15.0-16.3 years), 83 (22%) participants died, 60 (15%) reached the composite endpoint of AF and IS, and 38 (10%) reached the composite MACE endpoint. LA dyssynchrony was a univariable predictor of all-cause mortality (HR 1.07, 95% CI 1.02-1.11, p = 0.001) but was not significantly associated with the combined endpoint of AF and IS (HR 1.05, p = 0.064) nor MACE (HR 1.04, p = 0.22). However, when adjusted for age, LA dyssynchrony did not predict all-cause mortality (HR 1.03, p = 0.28). Similarly, after further adjustments for clinical and echocardiographic parameters LA dyssynchrony did not predict any of the study outcomes. In this general population study, LA dyssynchrony was not an independent predictor of all-cause mortality and did not predict MACE nor a composite outcome consisting of AF and IS.