Incident atrial fibrillation and heart failure in treated hypertensive patients with left ventricular hypertrophy

Background

Hypertension and left ventricular hypertrophy (LVH) are predictors of atrial fibrillation (AF) and heart failure (HF). The incidence rates of AF and HF and especially the combination of these two complications in hypertensive patients with LVH receiving antihypertensive treatment are unknown, and so are the association with risk levels of other cardiovascular diseases and death in hypertensive patients with LVH who develop new onset AF and HF.

Purpose

We aimed to investigate the appearance and severity of AF and HF in 8,702 hypertensive patients aged 55–80 years with LVH receiving antihypertensive treatment in a prospective and randomized clinical trial primarily designed to investigate the preventive effect on a composite endpoint of myocardial infarction, stroke and cardiovascular death.

Methods

Included were patients who had sinus rhythm in ECG and no history of AF or HF when they were randomly allocated to blinded study medication with losartan or atenolol. Additional medication was given with hydrochlorothiazide and calcium antagonist if needed to gain blood pressure control. Incident AF was detected by annual ECGs and from adverse event reports submitted by the 930 clinical investigators. Incident HF was diagnosed according to Framingham criteria. Endpoints including incident HF, myocardial infarction, stroke and cardiovascular death were reported with relevant documentation by the investigators, and adjudicated by an expert endpoint committee.

Results

Incident AF occurred in 679 patients (7.8%) and HF in 246 patients (2.8%) during 4.7±1.1 years mean follow-up. Incident AF was associated with a >4-fold increased risk of developing subsequent HF (HR=4.7; 95% CIs, 3.1–7.0; P<0.001) in multivariable Cox analyses adjusting for age, sex, race, randomized treatment, standard cardiovascular risk factors and incident myocardial infarction. The development of HF as a time-dependent variable was associated with a multivariable-adjusted 3-fold increase of the primary study endpoint (HR=3.11; 95% CIs, 1.52 to 6.39; P<0.001) which was the composite of myocardial infarction, stroke or cardiovascular death.

Incident HF was associated with a >3-fold increased risk of developing subsequent AF (HR=3.3; 95% CIs, 2.3–4.9; P<0.001). This development of AF was associated with more than a 2-fold increase of the composite of myocardial infarction, stroke or cardiovascular death in multivariable Cox analysis (HR=2.26; 95% CIs, 1.09–4.67; P=0.028).

Conclusions

Incident atrial fibrillation and heart failure are associated with increased risk of the other in treated hypertensive patients with left ventricular hypertrophy. These hypertensive patients who subsequently develop both atrial fibrillation and heart failure during antihypertensive treatment have particularly high risk of an additional composite endpoint consisting of myocardial infarction, stroke or cardiovascular death.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): The study originally received support from Merck & Co., Inc.

High-sensitive Troponin T in asymptomatic aortic stenosis

Background

High-sensitive cardiac Troponin T (hsTnT) is the most frequently used biomarker for the detection of cardiomyocyte injury. Severe aortic stenosis (AS) leads to an increased left ventricular load, with the potential of myocardial injury reflected by increased TnT levels. However, there is a lack of studies showing the prevalence and prognostic role of elevated hsTnT in patients with asymptomatic AS.

Purpose

To examine the association between the hsTnT levels and AS severity in asymptomatic AS patients. We hypothesized that patients with more severe AS will have elevated hsTnT levels and that hsTnT levels are associated with a higher risk for aortic valve events (AVE) and all-cause mortality (ACM).

Methods

We performed a post-hoc analysis in 1739 asymptomatic patients with mild to moderate-severe AS, enrolled in the randomized, double-blinded SEAS-study (Simvastatin and Ezetimibe in Aortic Stenosis). All patients had available hsTnT blood samples measured at baseline (Year 0) and Year 1. We defined moderate to severe (mod-severe) AS as a transaortic maximal outflow velocity (Vmax)>3.5 m/s combined with aortic valve area (AVA)<1.0 cm2, otherwise non-severe AS. An hsTnT>14 ng/L was high according to assay (Roche, Elecsys Troponin T hs on cobas e 601).

Linear multivariable regression model examined the association of hsTnT levels to clinical and echocardiographic variables.

Cox multivariable regression model evaluated competing risks and hazard ratios (HR) of outcomes while adjusting for relevant variables, including a Framingham 10-years risk score of cardiovascular diseases. The competing risks were either ACM or AVE, i.e. the first of AVR, cardiovascular death and heart failure due to AS progression.

Results

At baseline, hsTnT was high in 26% (453/1739) patients; 25% (380/1529) in non-severe and 35% (73/210) in mod-severe AS. Relative TnT change over one year was 17% (mean 1.17, SD 1.01); 15% in non-severe vs. 32% in mod-severe AS, and neither associated to AS severity, hsTnT at baseline or lipid-lowering treatment.

In multivariable linear regression analysis, there were significant correlations between hsTnT at baseline and age, male gender, creatinine, left ventricular mass index and BMI (all p<0.001, R-square=0.42), but not with AS severity.

In multivariable Cox regression analyses, a high hsTnT at baseline was associated with AVE 1.61 [95% CI 1.29–1.99]. In contrast, hsTnT at baseline was not associated to all-cause mortality (see figure).

Conclusions

In asymptomatic AS patients without severe AS, high-sensitive Troponin T is not associated with AS severity in cross-sectional analyses, and its levels do not change substantially during one year of follow-up. However, patients with hsTnT >14 ng/l had a sixty percent higher independent risk of subsequent aortic valve events.

Multivariable Cox regression

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Acknowledgements: Main sponsor (SEAS): MSD Singapore Company, LLC, partnership between Merck & Co. Inc. and Schering-Plough Corporation. Blood analysis sponsor: Roche

The influence of refractive index change and initial bending of cantilevers on the optical lever readout method

It has been speculated that the initial bending of cantilevers has a major influence on the detector signal in a cantilever-based sensor using the optical lever readout method. We have investigated theoretically as well as experimentally the changes induced in the detector signal when the optical lever technique is used to monitor a cantilever with initial bending during changes in the refractive index of the surrounding media. We find that for changes in refractive index as small as 10(-4) the detector signal is highly dependent on the initial bending of the cantilever. The findings are validated experimentally using an environmental chamber and varying the pressure. We sketch routes to circumvent the problem and formulas suitable for data treatment are given.

Dynamics and robustness of familiarity memory

When presented with an item or a face, one might have a sense of recognition without the ability to recall when or where the stimulus has been encountered before. This sense of recognition is called familiarity memory. Following previous computational studies of familiarity memory, we investigate the dynamical properties of familiarity discrimination and contrast two different familiarity discriminators: one based on the energy of the neural network and the other based on the time derivative of the energy. We show how the familiarity signal decays rapidly after stimulus presentation. For both discriminators, we calculate the capacity using mean field analysis. Compared to recall capacity (the classical associative memory in Hopfield nets), both the energy and the slope discriminators have bigger capacity, yet the energy-based discriminator has a higher capacity than one based on its time derivative. Finally, both discriminators are found to have a different noise dependence.

Cassegrainian/Gregorian-type null correctors for surface measurements of radio telescope reflectors

The (sub)millimeter wavelength radio observatory of the next generation will probably be an interferometer array of some 50 telescopes with parabolic reflectors 10-15 m in diameter. At this scale of mass production it is convenient to have at hand for workshop assembly a reflector surface measurement technique that is precise and easy to operate. We discuss the possibility of reflector measurements based on 10.6-microm CO2 laser interferometry using Cassegrainian/Gregorian-type null correctors.

Strehl number degradation by large-scale systematic surface deviations

Experience shows that optical and radio reflector surfaces may have systematic residual deviations to which the statistical analysis is not necessarily applicable. For large-scale systematic deviations we derive a general expression for calculating the degraded on-axis intensity, i.e., the Strehl number. For this type of deviation we introduce a quasi-rms value, which has the same optical significance as the rms value of random surface deviations. Numerical examples of realistic cases are presented.