Plasma biomarkers outperform echocardiographic measurements for cardiovascular risk prediction in kidney transplant recipients: results of the HOME ALONE study

Background

Since kidney transplant recipients (KTRs) have a high cardiovascular disease burden, adequate risk prediction is of importance. Whether echocardiographic parameters and plasma biomarkers, natriuretic peptides [N-terminal pro-B-type natriuretic peptide (NT-proBNP)] and troponin T provide complementary or overlapping prognostic information on cardiovascular events remains uncertain.

Methods

The prospective Heterogeneity of Monocytes and Echocardiography Among Allograft Recipients in Nephrology (HOME ALONE) study followed 177 KTRs for 5.4 ± 1.7 years. Predefined endpoints were hospitalization for acute decompensated heart failure or all-cause death (HF/D) and major atherosclerotic cardiovascular events or all-cause death (MACE/D). At baseline, plasma NT-proBNP, plasma troponin T and echocardiographic parameters [left atrial volume index, left ventricular (LV) mass index, LV ejection fraction, and LV filling pressure] were assessed.

Results

Among all echocardiographic and plasma biomarkers measured, only NT-proBNP was consistently associated with HF/D in univariate and multivariate {third versus first tertile: hazard ratio [HR] 4.20 [95% confidence interval (CI) 1.02–17.27]} analysis, and only troponin T was consistently associated with MACE/D in univariate and multivariate [third versus first tertile: HR 8.15 (95% CI 2.75–24.18)] analysis.

Conclusion

Our data suggest that plasma biomarkers are robust and independent predictors of heart failure and atherosclerotic cardiovascular events after kidney transplantation, whereas standard echocardiographic follow-up does not add to risk prediction.

Conventional and new electrocardiographic criteria for hypertension-mediated cardiac organ damage: A narrative review

Hypertension-mediated organ damage (HMOD) is frequently observed in hypertensive patients at different cardiovascular (CV) risk profile. This may have both diagnostic and therapeutic implications for the choice of the most appropriate therapies. Among different markers of HMOD, the most frequent functional and structural adaptations can be observed at cardiac level, including left ventricular hypertrophy (LVH), diastolic dysfunction, aortic root dilatation, and left atrial enlargement. In particular, LVH was shown to be a strong and independent risk factor for major CV events, namely myocardial infarction, stroke, congestive heart failure, CV death. Thus, early identification of LVH is a key element for preventing CV events in hypertension. Although echocardiographic assessment of LVH represents the gold standard technique, this is not cost-effective and cannot be adopted in routine clinical practice of hypertension. On the other hand, electrocardiographic (ECG) assessment of HMOD relative to the heart is a simple, reproducible, widely available and cost-effective method to assess the presence of LVH, and could be preferred in large scale screening tests. Several new indicators have been proposed and tested in observational studies and clinical trials of hypertension, in order to improve the relatively low sensitivity of the conventional ECG criteria for LVH, despite high specificity. This article reviews the differences in the use of the main conventional and the new 12 lead ECG criteria of LVH for early assessment of asymptomatic, subclinical cardiac HMOD in a setting of clinical practice of hypertension.

Effects of Metabolically Healthy and Unhealthy Obesity on Prolongation of Corrected QT Interval

Although obesity and the metabolic syndrome (MS) often co-occur, many obese (OB) subjects have a favorable metabolic profile. It is unclear whether these factors independently influence cardiac electrophysiology including prolongation of the QT interval. We examined associations among obesity, MS, and prolonged corrected QT (QTc) interval in a large sample of Chinese research participants aged ≥35 years recruited from rural areas of Liaoning Province during 2012 to 2013. Of the 11,209 participants, 6,364 (56.8%) were nonobese and metabolically healthy (OB-/MS-), 2,853 (25.5%) were OB-/MS+, 493 (4.4%) were OB+/MS-, and 1,499 (13.4%) were OB+/MS+. Mean (±SD) QTc intervals were higher in OB-/MS+ (436.3 ± 24.3) and OB+/MS+ (436.6 ± 25.9) participants but not OB+/MS- participants (425.4 ± 24.0) than in OB-/MS- participants (426.8 ± 21.5, p <0.001), and the prevalence of QTc prolongation was higher in OB-/MS+ and OB+/MS+ participants (adjusted odds ratios [aOR] 1.68, 95% confidence interval [CI] 1.52 to 1.85; aOR 1.92, 95% CI 1.69 to 2.17, respectively) compared with OB-/MS- group but not in OB+/MS- participants (aOR 0.92, 95% CI 0.73 to 1.15). Prevalence increased with each MS component (aOR 1.27, 95% CI 1.22 to 1.32) but not with body mass index (aOR 1.01, 95% CI 0.99 to 1.02). In conclusion, prolonged QTc interval is associated with the MS and not independently associated with obesity.

Recent heart rate history affects QT interval duration in atrial fibrillation

QT interval prolongation is associated with a risk of polymorphic ventricular tachycardia. QT interval shortens with increasing heart rate and correction for this effect is necessary for meaningful QT interval assessment. We aim to improve current methods of correcting the QT interval during atrial fibrillation (AF). Digitized Holter recordings were analyzed from patients with AF. Models of QT interval dependence on RR intervals were tested by sorting the beats into 20 bins based on corrected RR interval and assessing ST-T variability within the bins. Signal-averaging within bins was performed to determine QT/RR dependence. Data from 30 patients (29 men, 69.3±7.3 years) were evaluated. QT behavior in AF is well described by a linear function (slope ~0.19) of steady-state corrected RR interval. Corrected RR is calculated as a combination of an exponential weight function with time-constant of 2 minutes and a smaller “immediate response” component (weight ~ 0.18). This model performs significantly (p<0.0001) better than models based on instantaneous RR interval only including Bazett and Fridericia. It also outperforms models based on shorter time-constants and other previously proposed models. This model may improve detection of repolarization delay in AF. QT response to heart rate changes in AF is similar to previously published QT dynamics during atrial pacing and in sinus rhythm.

Electrocardiographic Abnormalities and QTc Interval in Patients Undergoing Hemodialysis

Background

Sudden cardiac death is one of the primary causes of mortality in chronic hemodialysis (HD) patients. Prolonged QT_c interval is associated with increased rate of sudden cardiac death. The aim of this article is to assess the abnormalities found in electrocardiograms (ECGs), and to explore factors that can influence the QT_c interval.

Methods

A total of 141 conventional HD patients were enrolled in this study. ECG tests were conducted on each patient before a single dialysis session and 15 minutes before the end of dialysis session (at peak stress). Echocardiography tests were conducted before dialysis session began. Blood samples were drawn by phlebotomy immediately before and after the dialysis session.

Results

Before dialysis, 93.62% of the patients were in sinus rhythm, and approximately 65% of the patients showed a prolonged QT_c interval (i.e., a QT_c interval above 440 ms in males and above 460ms in females). A comparison of ECG parameters before dialysis and at peak stress showed increases in heart rate (77.45±11.92 vs. 80.38±14.65 bpm, p = 0.001) and QT_c interval (460.05±24.53 ms vs. 470.93±24.92 ms, p<0.001). After dividing patients into two groups according to the QT_c interval, lower pre-dialysis serum concentrations of potassium (K⁺), calcium (Ca²⁺), phosphorus, calcium* phosphorus (Ca*P), and higher concentrations of plasma brain natriuretic peptide (BNP) were found in the group with prolonged QT_c intervals. Patients in this group also had a larger left atrial diameter (LAD) and a thicker interventricular septum, and they tended to be older than patients in the other group. Then patients were divided into two groups according to ΔQT_c (ΔQT_c = QT_{c peak-stress}- QT_{c pre-HD}). When analyzing the patients whose QT_c intervals were longer at peak stress than before HD, we found that they had higher concentrations of Ca²⁺ and P⁵⁺ and lower concentrations of K⁺, ferritin, UA, and BNP. They were also more likely to be female. In addition, more cardiac construction abnormalities were found in this group. In multiple regression analyses, serum Ca²⁺ concentration before HD and LAD were independent variables of QT_c interval prolongation. UA, ferritin, and interventricular septum were independent variables of ΔQT_c.

Conclusion

Prolonged QT interval is very common in HD patients and is associated with several risk factors. An appropriate concentration of dialysate electrolytes should be chosen depending on patients’ clinical conditions.