Detection of T-wave beat-by-beat variations prior to ventricular arrhythmias onset in ICD-stored intracardiac electrograms: the Endocardial T-Wave Alternans Study (ETWAS).

BACKGROUND: The aim of the Endocardial T-Wave Alternans Study was to prospectively assess the presence of T-wave alternans (TWA) or beat-to-beat repolarization changes on implantable cardioverter-defibrillator (ICD)-stored electrograms (EGMs) immediately preceding the onset of spontaneous ventricular tachycardia (VT) or fibrillation (VF). METHODS: Thirty-seven VT/VF episodes were compared to 116 baseline reference EGMs from the same 57 patients. A Bayesian model was used to estimate the T-wave waveform in each cardiac beat and a set of 10 parameters was selected to segment each detected T wave. Beat-by-beat differences in each T-wave parameter were computed using the absolute value of the difference between each beat and the following one. Fisher criterion was used for determining the most discriminant T-wave parameters, then top-M ranked parameters yielding a normalized cumulative Fisher score > 95% were selected, and analysis was applied on these selected parameters. Simulated TWA EGMs were used to validate the algorithm. RESULTS: In the simulation study, TWA was detectable even in the case of the smallest simulated alternans of 25 µV. In 13 of the 37 episodes (35%) occurring in nine of 16 patients, significant larger beat-to-beat variations before arrhythmia onset were detected compared to their respective references (median one positive episode per patient). Parameters including the T-wave apex amplitude seem the more discriminant parameters. CONCLUSIONS: Detection of beat-by-beat repolarization variations in ICD-stored EGMs is feasible in a significant subset of cases and may be used for predicting the onset of ventricular arrhythmias.

Structured syncope care pathways based on lean six sigma methodology optimises resource use with shorter time to diagnosis and increased diagnostic yield.

AIMS: To conduct a pilot study on the potential to optimise care pathways in syncope/Transient Loss of Consciousness management by using Lean Six Sigma methodology while maintaining compliance with ESC and/or NICE guidelines. METHODS: Five hospitals in four European countries took part. The Lean Six Sigma methodology consisted of 3 phases: 1) Assessment phase, in which baseline performance was mapped in each centre, processes were evaluated and a new operational model was developed with an improvement plan that included best practices and change management; 2) Improvement phase, in which optimisation pathways and standardised best practice tools and forms were developed and implemented. Staff were trained on new processes and change-management support provided; 3) Sustaining phase, which included support, refinement of tools and metrics. The impact of the implementation of new pathways was evaluated on number of tests performed, diagnostic yield, time to diagnosis and compliance with guidelines. One hospital with focus on geriatric populations was analysed separately from the other four. RESULTS: With the new pathways, there was a 59% reduction in the average time to diagnosis (p = 0.048) and a 75% increase in diagnostic yield (p = 0.007). There was a marked reduction in repetitions of diagnostic tests and improved prioritisation of indicated tests. CONCLUSIONS: Applying a structured Lean Six Sigma based methodology to pathways for syncope management has the potential to improve time to diagnosis and diagnostic yield.

A case of cardiomyopathy induced by inappropriate sinus tachycardia and cured by ivabradine.

We present the case of a 67-year-old woman with cardiomyopathy induced by inappropriate sinus tachycardia (IST) and a particularly high average heart rate. The patient was resistant and/or intolerant to treatment with conventional rate-slowing medications. We used ivabradine--a specific sinus node I(f) current inhibitor--and successfully lowered the heart rate (33 beats per minute mean heart rate decrease). Symptoms, systolic function, and heart rate variability parameters recovered dramatically. No side effect was noted. We suggest that ivabradine--evaluated in trials to treat stable angina--should be considered as a second-line treatment in patients with very symptomatic and refractory IST.

Diastolic asynchrony is more frequent than systolic asynchrony in dilated cardiomyopathy and is less improved by cardiac resynchronization therapy.

OBJECTIVES: To compare the incidence of diastolic and systolic asynchrony, assessed by tissue Doppler imaging (TDI), in patients with congestive heart failure (CHF) and severe left ventricular (LV) dysfunction, and to assess TDI changes induced by cardiac resynchronization therapy (CRT). BACKGROUND: Thirty percent of CRT candidates are nonresponders. Besides QRS width, the presence of echographic systolic asynchrony has been used to identify future responders. Little is known about diastolic asynchrony and its change after CRT. METHODS: Tissue Doppler imaging was performed in 116 CHF patients (LV ejection fraction 26 +/- 8%). Systolic and diastolic asynchrony was calculated using TDI recordings of right ventricular and LV walls. RESULTS: The CHF group consisted of 116 patients. Diastolic asynchrony was more frequent than systolic, concerning both intraventricular (58% vs. 47%; p = 0.0004) and interventricular (72 vs. 45%; p < 0.0001) asynchrony. Systolic and diastolic asynchrony were both present in 41% patients, but one-third had isolated diastolic asynchrony. Although diastolic delays increased with QRS duration, 42% patients with narrow QRS presented with diastolic asynchrony. Conversely, 27% patients with large QRS had no diastolic asynchrony. Forty-two patients underwent CRT. Incidence of systolic intraventricular asynchrony decreased from 71% to 33% after CRT (p < 0.0001), but diastolic asynchrony decreased only from 81% to 55% (p < 0.0002). Cardiac resynchronization therapy induced new diastolic asynchrony in eight patients. CONCLUSIONS: Diastolic asynchrony is weakly correlated with QRS duration, is more frequent than systolic asynchrony, and may be observed alone. Diastolic asynchrony is less improved by CRT than systolic. Persistent diastolic asynchrony may explain some cases of lack of improvement after CRT despite good systolic resynchronization.

Effect of maturational status and training on upper limb pulse wave velocity.

UNLABELLED: Cardiovascular adaptations to training may include changes in arterial distensibility, although studies involving sick and healthy individuals have yielded contradictory results. Moreover, despite the fact that endurance training frequently begins in childhood, its influence on arterial distensibility is less well characterised in children. This study was therefore to compare the upper limb pulse wave velocity (PWVUL) in highly trained prepubertal swimmers and age-matched moderately active counterparts, with that in swimmers and sedentary adults. The aim was to investigate the effects of maturation and training status on PWVUL in healthy individuals. PWVUL was evaluated by a dedicated continuous wave Doppler and photoplethysmography system. We calculated the pressure-corrected index of distensibility (Cp) which provides a measure of intrinsic structural compliance of the artery wall. PWVUL was significantly higher in highly trained child swimmers compared to moderately active ones (6.17+/-0.49 versus 5.20+/-0.38 ms(-1), P <0.05) even when mean arterial pressure was fixed as a covariate. Cp was significantly lower in child swimmers than in moderately active ones (0.15+/-0.03 versus 0.18+/-0.04, P <0.05 respectively) whereas Cp was not significantly different in either adult group. The PWVUL and Cp values of child swimmers were similar to those of adults. CONCLUSION: Our results confirmed an increase in pulse wave velocity with maturation implying that compliance decreases with age. An unexpected result was that swimming training performed in children over a long period led to an increase in upper limb pulse wave velocity. This change, concerning the upper limbs which are strongly involved in swimming, may be related to enhanced smooth muscle content of the arterial wall, possibly due to intermittent elevations in arterial blood pressure during repetitive swimming exercise sessions. Whether adaptations to intensive swimming training are accompanied by alterations of the cardiovascular system in prepubertal children is an important question to be dealt with in further studies.

Prognostic value of cardiac troponin T in patients with both acute and chronic stable congestive heart failure: comparison with atrial natriuretic peptide, brain natriuretic peptide and plasma norepinephrine.

BACKGROUND: The prognostic value of cardiac troponin T (cTn-T) in a mixture of patients with both acute and chronic congestive heart failure (CHF), simultaneously assessed and compared with neurohormonal factors, has not yet been thoroughly evaluated. Thus, we focused on the prognostic value of cTn-T in comparison with atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and plasma norepinephrine (PNE) in this population. METHODS: Prognostic correlates of elevation of cTn-T, ANP, BNP, PNE were analyzed in 63 acute and chronic CHF patients followed up to record worsening CHF and cardiac death. RESULTS: cTn-T (> or =0.03 microg/L) was found in 17.4% (11 of 63) of patients. cTn-T correlated with ANP, BNP, PNE. Acute CHF patients were more positive for cTn-T and BNP. In our cohort, neither cTn-T (> or =0.03 microg/L) nor PNE were associated with increased mortality and worsening HF in CHF patients. After adjustment, BNP was the only independent predictor of cardiac events (RR, 3.23; p=0.01). CONCLUSIONS: BNP emerged as the only independent predictor of cardiac events in a mixture of patients with both acute and chronic CHF, suggesting that it is the analyte that best reflects long-term prognosis in a diverse population enrolled to mirror the "real world" situation.