Lack of diurnal variation of P-wave and QT dispersions in patients with heart failure

Effects of angiotensin receptor neprilysin inhibition on P-wave dispersion in heart failure with reduced ejection fraction

BACKGROUND

Angiotensin receptor neprilysin inhibitors (ARNI; sacubitril/valsartan combination) decrease morbidity and mortality in heart failure with reduced ejection fraction (HFrEF). Increased P‑wave duration and P‑wave dispersion (P_d) reflect prolongation of atrial conduction and correlate with atrial fibrillation. Here, we aimed to assess the effects of switching from valsartan to ARNI treatment on the basis of P‑wave indices.

METHODS

A total of 28 patients with HFrEF (mean age, 64.8 ± 10.6 years; 18 males, 78.6% ischemic etiology) were included. All patients had New York Heart Association functional class II-III, left ventricular ejection fraction ≤35%, and had been switched from valsartan to ARNI treatment. Standard 12-lead electrocardiograms from patients on valsartan treatment and electrocardiograms 1 month after ARNI treatment were analyzed; heart rate, maximum P‑wave duration (P_max), minimum P‑wave duration (P_min), and P_d were calculated. Minnesota Living with Heart Failure Questionnaire (MLWHFQ) scores and N‑terminal pro-brain natriuretic peptide (NT-proBNP) values were recorded.

RESULTS

The P_max (135.6 ± 32.1 ms vs. 116.1 ± 14.1 ms, p = 0.041) and P_d (33.6 ± 7.9 vs. 28.6 ± 5.3, p = 0.006) values were significantly reduced after ARNI treatment. Furthermore, ARNI treatment was associated with an improvement in MLWHFQ scores (31.2 ± 6.2 ms vs. 23.2 ± 7.0 ms, p < 0.001) and with a reduction in NT-proBNP values (1827.3 ± 1287.3 pg/ml vs. 1074.4 ± 692.3 pg/ml, p < 0.001). There were moderately positive correlations between the reduction in P_d and the improvement in MLWHFQ scores (r = 0.408, p = 0.031) and the reduction in NT-proBNP values (r = 0.499, p = 0.007) CONCLUSION: Switching to ARNI treatment alters P_d and P_max favorably in patients with HFrEF. The reduction in atrial inhomogeneous conduction assessed by P_d was correlated with clinical improvement and reduced NT-proBNP levels in patients with HFrEF.

Prevalence of P wave dispersion and interatrial block in patients with systolic heart failure and their relationship with functional status, hospitalization and one year mortality

Background and objectives

P-wave dispersion (PWD) and Interatrial block (IAB) are common in heart failure (HF), and could be associated with adverse cardiac events. We aimed to assess the prevalence of PWD and IAB and their relationship with functional status, hospitalization and mortality rate in patients with systolic HF.

Methods

We enrolled 110 HF patients in sinus rhythm & LVEF <50%. Patients had undergone clinical evaluation, 6 min walking test (6MWT), 12-lead electrocardiography (ECG), 24-h Holter ECG & echocardiogram. Hospitalization and mortality rate were followed-up for one year. PWD was defined as the difference between maximum & minimum P-wave duration >40 ms. IAB was defined as maximum P duration >110 ms. Measurements were done by 2 blinded investigators using a caliber, a ruler and a magnifying lens.

Results

Mean age was 58.9 ± 9.7 years and 67.3% were males. Prevalence of PWD and IAB was 68.2% and 57.3%, respectively. Patients with PWD showed these features: 84% in NYHA class III or IV HF, 77.4% had LVEF <35%, 78.7% had paroxysmal Atrial Fibrillation (AF) and 89.4% couldn’t complete >200 m (m) in 6MWT. Patients with PWD had more hospitalizations (72% vs 28.6%, P value <0.02) and higher 1-year mortality rate (20% vs 8.6%, P value <0.04) than patients without PWD. Likewise, patients with IAB had nearly similar clinical features, hospitalization and mortality as patients with PWD.

Conclusion

PWD and IAB are prevalent in patients with systolic HF and they are significantly associated with low LVEF, paroxysmal AF, poor functional capacity, hospitalization and mortality rate.

P-wave dispersion: What we know till now?

P-wave dispersion is defined as the difference between the maximum and the minimum P-wave duration recorded from multiple different-surface ECG leads. It has been known that increased P-wave duration and P-wave dispersion reflect prolongation of intraatrial and interatrial conduction time and the inhomogeneous propagation of sinus impulses, which are well-known electrophysiologic characteristics in patients with atrial arrhythmias and especially paroxysmal atrial fibrillation. Extensive clinical evaluation of P-wave dispersion has been performed in the assessment of the risk for atrial fibrillation in patients without apparent heart disease, in hypertensives, in patients with coronary artery disease, in patients undergoing coronary artery bypass surgery, in patients with congenital heart diseases, as well as in other groups of patients suffering from various cardiac or non-cardiac diseases. In this paper, we aimed to summarize the measurement methods, current use in different clinical situations, strengths and limitations of the of P-wave dispersion.

Light-dark dependence of electrocardiographic changes during asphyxia and reoxygenation in a rat model

The aim of this study was to evaluate the effect of ventilation on electrocardiographic time intervals as a function of the light-dark (LD) cycle in an in vivo rat model. RR, PQ, QT and QTc intervals were measured in female Wistar rats anaesthetized with both ketamine and xylazine (100 mg/15 mg/kg, i.m., open chest experiments) after adaptation to the LD cycle (12:12h) for 4 weeks. Electrocardiograms (ECG) were recorded before surgical interventions; after tracheotomy, and thoracotomy, and 5 minutes of stabilization with artificial ventilation; 30, 60, 90 and 120 seconds after the onset of apnoea; and after 5, 10, 15, and 20 minutes of artificial reoxygenation. Time intervals in intact animals showed significant LD differences, except in the QT interval. The initial significant (p<0,001) LD differences in PQ interval and loss of dependence on LD cycle in the QT interval were preserved during short-term apnoea-induced asphyxia (30–60 sec) In contrast, long-term asphyxia (90–120 sec) eliminated LD dependence in the PQ interval, but significant LD differences were shown in the QT interval. Apnoea completely abolished LD differences in the RR interval. Reoxygenation restored the PQ and QT intervals to the pre-asphyxic LD differences, but with the RR intervals, the LD differences were eliminated. We have concluded that myocardial vulnerability is dependent on the LD cycle and on changes of pulmonary ventilation.