Heart rate-corrected QT interval and QT dispersion in patients with pulmonary hypertension

A 4-Day Exposure to High Altitude Prolongs QTc in Healthy Human Subjects

IntroductionLong QTc syndrome can predispose patients to fatal ventricular arrhythmias. We studied the effects of a rapid ascent and a multiday stay at high altitude on QTc interval.MethodsWe recorded electrocardiograms (ECGs) on study subjects at sea level and then again after a 1-d ascent to 3800 m. Two sea-level ECGs were recorded at the initial screening visit (SL1) and 14 days later (SL2). Altitude ECGs were recorded at approximately 16 and 86 h after arrival. SpO2 was recorded prior to each ECG measurement. We defined prolonged QTc as a QTc interval >450 ms for men and >470 ms for women. We used multivariate analysis to analyze the QTc interval for the effect of drugs, altitude, and changes in electrolytes.ResultsWe enrolled 107 subjects: 61 males and 46 females between the ages of 19 and 54 y, with a median age of 34 y. QTcF (QT interval for varying heart rates using Fridericia's formula) at SL1 was 405±17 ms; at SL2, 404±17 ms; at 16 h, 411±18 ms; and at 86 h, 427±24 ms. After 86 h at altitude, 12 participants met the criteria for prolonged QT syndrome, and 61% of subjects had QTc prolongation of >20 ms from sea-level values. This was independent of changes in serum electrolyte levels, (i.e., sodium, potassium, and calcium), bicarbonate levels, and SpO2.ConclusionHigh altitude exposure can lengthen a healthy adult's QTc interval by more than 20 ms. It remains unknown whether this increase might raise the risk of torsades de pointes in people with long QT intervals at baseline.

Fragmented QRS complex could predict all-cause mortality in patients with connective tissue disease-associated pulmonary arterial hypertension

OBJECTIVES

To investigate the prognostic impact and pathophysiological characteristics of fragmented QRS complex (fQRS) on patients with CTD-associated pulmonary arterial hypertension (CTD-PAH).

METHODS

This was a multicentre retrospective study recruiting 141 patients with CTD-PAH diagnosed by right heart catheterization (114 cases in the discovery cohort and 27 cases in the validation cohort). fQRS and ST-T change were detected on conventional 12-lead ECG. Patients were followed up every 3 months to update their status and the primary endpoint was all-cause death. Clinical information and ECG characteristics were compared between survival and death groups and Kaplan-Meier curve was used for survival analysis.

RESULTS

There were significant differences in age, gender, 6-min walk distance, N-terminal pro-brain natriuretic peptide, World Health Organization class, presence of fQRS, and presence of ST-T change in inferior leads between survival group and death group. Inferior fQRS and ST-T change were significantly associated with right ventricular dilatation and reduced right ventricular ejection fraction. Kaplan-Meier curve showed that all-cause mortality was higher in CTD-PAH with fQRS (P = 0.003) and inferior ST-T change (P = 0.012). Low- and intermediate-risk CTD-PAH with inferior ST-T change had higher all-cause mortality (P = 0.005). The prognostic value of fQRS and inferior ST-T change was validated in external validation cohort.

CONCLUSION

The presence of inferior fQRS and ST-T change could predict poor prognosis in CTD-PAH.

CLINICAL TRIAL REGISTRATION

NCT05980728, https://clinicaltrials.gov.

Unraveling the Complex Relationship-Atrial Fibrillation and Pulmonary Hypertension

PURPOSE OF REVIEW

In this article, we underscore the importance of identifying risk factors and monitoring pulmonary hypertension patients for signs of arrhythmias, as this proactive approach can reduce morbidity and mortality.

RECENT FINDINGS

Atrial fibrillation is the most prevalent among cardiac arrhythmias and is associated with an increased risk of stroke, morbidity, and mortality. Smoking, obesity, hypertension, a sedentary lifestyle, and diabetes mellitus are some of the modifiable risk factors for atrial fibrillation. Recent studies show that the risk of atrial fibrillation is rising in patients with parenchymal and vascular lung disease. Stretching in the atria and pulmonary veins may lead to the onset of atrial fibrillation in cardiac conditions like hypertension, heart failure, and valvular disease. Atrial fibrillation in patients with pulmonary hypertension (PH) denotes a more advanced disease. Patients with PH are more susceptible to hemodynamic stress caused by tachycardia and an uncoordinated atrioventricular contraction. Therefore, atrial arrhythmias need to be treated because inadequate control of cardiac arrhythmias may result in poor clinical outcomes and lead to disease progression in PH patients. Aside from being a sign of severe disease, AF can also speed up and exacerbate the condition.

Cardiac Arrhythmias in Pulmonary Arterial Hypertension and Chronic Thromboembolic Pulmonary Hypertension: Mechanistic Insights, Pathophysiology, and Outcomes

Arrhythmias are increasingly recognized as severe complications of precapillary pulmonary hypertension, encompassing pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). Despite their significant contribution to symptoms, morbidity, in-hospital mortality, and potentially sudden death in PAH/CTEPH, there remains a lack of comprehensive data on epidemiology, pathophysiology, and outcomes to inform the management of these patients. This review provides an overview of the latest evidence on this subject, spanning from the molecular mechanisms underlying arrhythmias in the hypertrophied or failing right heart to the clinical aspects of epidemiology, diagnosis, and treatment.

Electrocardiogram in patients with pulmonary hypertension

INTRODUCTION

Pulmonary hypertension (PH) is a potentially life-threatening cardiovascular disease defined by a mean pulmonary arterial pressure (mPAP) > 20 mmHg. Due to non-specific symptoms, PH is often diagnosed late and at advanced stage. In addition to other diagnostic modalities, the electrocardiogram (ECG) can help in establishing the diagnosis. Knowledge of typical ECG signs could help to detect PH earlier.

METHODS

A non-systematic literature review on the typical electrocardiographic patterns of PH was performed.

RESULTS

Characteristic signs of PH include right axis deviation, SIQIIITIII and SISIISIII patterns, P pulmonale, right bundle branch block, deep R waves in V1 and V2, deep S waves in V5 and V6, and right ventricular hypertrophy (R in V1 + S in V5, V6 > 1,05 mV). Repolarisation abnormalities such as ST segment depressions or T wave inversions in leads II, III, aVF, and V1 to V3 are common as well. Furthermore, a prolonged QT/QTc interval, an increased heart rate, or supraventricular tachyarrhythmias can be observed. Some parameters may even provide information about the patient's prognosis.

CONCLUSION

Not every PH patient shows electrocardiographic PH signs, especially in mild PH. Thus, the ECG is not useful to completely rule out PH, but provides important clues to PH when symptoms are present. The combination of typical ECG signs and the co-occurrence of electrocardiographic signs with clinical symptoms and elevated BNP levels are particularly suspicious. Diagnosing PH earlier could prevent further right heart strain and improve patient prognosis.

Correlation Between QTc Dispersion and Soluble Growth-stimulating Gene 2 Protein on the Early Prognosis of Acute Carbon Monoxide Poisoning Heart Disease

ABSTRACT

This study aimed to explore the correlation between QTc dispersion (QTcd) and soluble growth-stimulating gene 2 protein (sST2) after heart rate correction in patients with acute carbon monoxide poisoning heart disease. Among the 150 patients, 35 cases had severe toxic heart disease. The concentrations of sST2, cardiac troponin I, and creatine kinase-MB in the severe group began to increase from admission, 24 hours, and 2 days, respectively, and their detected values were all higher than those in the nonsevere group and the normal control group. There were statistically significant differences in sST2 and QTcd between the poisoning, nonsevere, and normal control groups before the treatment. There was a statistically significant difference between the indexes of the poisoning groups at different degrees 2 and 3 days after poisoning. Receiver operating characteristic curve analysis confirmed the sensitivity and specificity of sST2 and QTcd. The correlation analysis showed that sST2 and QTcd levels were positively correlated with the incidence of severe heart disease at admission. Generally, the combined observation of sST2 and QTcd improved the prediction sensitivity and were early predictor indexes of toxic heart disease.

Electrocardiography (ECG) analysis and a new feature extraction method using wavelet transform with scalogram analysis

Electrocardiography (ECG) signals and the information obtained through the analysis of these signals constitute the main source of diagnosis for many cardiovascular system diseases. Therefore, accurate analyses of ECG signals are very important for correct diagnosis. In this study, an ECG analysis toolbox together with a user-friendly graphical user interface, which contains the all ECG analysis steps between the recording unit and the statistical investigation, is developed. Furthermore, a new feature calculation methodology is proposed for ECG analysis, which carries distinct information than amplitudes and durations of ECG main waves and can be used in artificial intelligence studies. Developed toolbox is tested using both Massachusetts Institute of Technology-Beth Israel Hospital (MIT-BIH) Arrhythmia ECG Database and an experimentally collected dataset for performance evaluation. The results show that ECG analysis toolbox presented in this study increases the accuracy and reliability of the ECG main wave detection analysis, highly fasten the process duration compared to manual ones and the new feature set can be used as a new parameter for decision support systems about ECG based on artificial intelligence.

Electrophysiological study and radiofrequency ablation of hemodynamically-instable ventricular arrhythmias in a patient with pulmonary hypertension: A case report

INTRODUCTION

Hemodynamically-instable ventricular arrhythmias (VAs) are rare in patients with pulmonary hypertension (PH). To the best of our knowledge, only 1 case has been reported so far. Moreover, the pathogenesis of this kind of arrhythmia remains obscured and its treatment is challenging. Here we report another case and presented the substrate for VAs initiation and therapeutic effect of radiofrequency ablation.

PATIENT CONCERNS

This is a 57-year-old man who presented paroxysmal palpitation associated with presyncope at rest. Surface electrocardiogram (ECG) revealed frequent ventricular premature contractions and non-sustained ventricular tachycardia when symptoms occurred. He also had a history of severe PH which was secondary to atrial septal defect and partial anomalous pulmonary venous drainage and suffered from obvious dyspnea when climbing stairs World Health Organization Class III (WHO Class III).

DIAGNOSIS

Hemodynamically-instable VAs associated with severe PH.

INTERVENTION

Echocardiography revealed enlargement of right ventricle (right ventricle [RV]: 43 mm). Electrophysiological examination showed the origin of VAs is next to a small low-voltage zone of RV. Radiofrequency delivery at the origin successfully terminated VAs without occurrence of complication.

OUTCOME

The patient was free from arrhythmias and got an improvement of exercise tolerance, just with mild dyspnea when climbing stairs World Health Organization Class II (WHO class II), during six-month follow up.

LESSONS

This case suggests the low-voltage zone of remodeled RV, which may be secondary to increased pulmonary artery pressure, serves as the substrate for VAs initiation in patient with PH. Radiofrequency ablation can successfully terminate VAs and the termination of VAs can significantly improve the patient's impaired exercise tolerance.

Altered cardiac repolarisation in highlanders with high-altitude pulmonary hypertension during wakefulness and sleep

High-altitude pulmonary hypertension (HAPH) is an altitude-related illness associated with hypoxaemia that may promote sympathetic excitation and prolongation of the QT interval. The present case-control study tests whether QT intervals, markers of malignant cardiac arrhythmias, are prolonged in highlanders with HAPH (HAPH+) compared to healthy highlanders (HH) and healthy lowlanders (LL). The mean pulmonary artery pressure (mPAP) was measured by echocardiography in 18 HAPH+ (mPAP, 34 mmHg) and 18 HH (mPAP, 23 mmHg) at 3,250 m, and 18 LL (mPAP, 18 mmHg) at 760 m, Kyrgyzstan (p < .05 all mPAP comparisons). Groups were matched for age, sex and body mass index. Electrocardiography and pulse oximetry were continuously recorded during nocturnal polysomnography. The heart rate-adjusted QT interval, QTc, was averaged over consecutive 1-min periods. Overall, a total of 26,855 averaged 1-min beat-by-beat periods were semi-automatically analysed. In HAPH+, maximum nocturnal QTc was longer during sleep (median 456 ms) than wakefulness (432 ms, p < .05) and exceeded corresponding values in HH (437 and 419 ms) and LL (430 and 406 ms), p < .05, respectively. The duration of night-time QTc >440 ms was longer in HAPH+ (median 144 min) than HH and LL (46 and 14 min, p < .05, respectively). HAPH+ had higher night-time heart rate (median 78 beats/min) than HH and LL (66 and 65 beats/min, p < .05, respectively), lower mean nocturnal oxygen saturation than LL (88% versus 95%, p < .05) and more cyclic oxygen desaturations (median 24/hr) than HH and LL (13 and 3/hr, p < .05, respectively). In conclusion, HAPH was associated with higher night-time heart rate, hypoxaemia and longer QTc versus HH and LL, and may represent a substrate for increased risk of malignant cardiac arrhythmias.

Predictive value of P-wave and QT interval dispersion in children with congenital heart disease and pulmonary arterial hypertension for the occurrence of arrhythmias

OBJECTIVES

To evaluate P-wave dispersion (PWD) and QT dispersion (QTd) in children with congenital heart disease and pulmonary arterial hypertension (PAH-CHD) and to investigate the predictive value of both PWD and QTd for prediction of arrhythmias in such children.

MATERIALS AND METHODS

We included 40 children with PAH-CHD as Group I. Forty other children with CHD and no PAH were included as Group II. Forty healthy children of matched age and sex served as a Control group. Electrocardiography was performed to determine PWD and QTd. Furthermore, 24-hour Holter monitoring was performed to detect the presence of arrhythmias. Echocardiographic evaluation was also performed.

RESULTS

QTd and PWD were significantly higher in Group I than in Group II and Control group. A significant positive correlation was present between both QTd and PWD and mean pulmonary artery pressure, right ventricular diameter, pulmonary vascular resistance (PVR), and PVR to systemic vascular resistance ratio. QTd showed 93% sensitivity, 80% specificity, and 85% accuracy for prediction of occurrence of arrhythmias in patients with PAH-CHD at a cutoff point of 61 ms, whereas PWD showed 87% sensitivity, 80% specificity, and 85% accuracy for prediction of arrhythmias at a cutoff point of 32.5 ms in such patients. Logistic regression analysis showed that both QTd and PWD were good predictors for the occurrence of arrhythmias in children with PAH-CHD (p = 0.003 and p = 0.01, respectively).

CONCLUSIONS

PWD and QTd were good predictors for the occurrence of various arrhythmias in children with PAH-CHD.

Pathophysiology, incidence, management, and consequences of cardiac arrhythmia in pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension

Arrhythmias are increasingly recognized as serious, end-stage complications of pre-capillary pulmonary hypertension, including pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). Although arrhythmias contribute to symptoms, morbidity, in-hospital mortality, and possibly sudden death in PAH/CTEPH, there remains a paucity of epidemiologic, pathophysiologic, and outcome data to guide management of these patients. This review summarizes the most current evidence on the topic: from the molecular mechanisms driving arrhythmia in the hypertrophied or failing right heart, to the clinical aspects of epidemiology, diagnosis, and management.

Increased microvolt T-wave alternans in children and adolescents with Eisenmenger syndrome

Objective:

To determine the values of microvolt T-wave alternans (MTWA) in children and adolescents with Eisenmenger syndrome (ES) and controls.

Methods:

Thirteen were included in the study. After analyzing the 24-h ECG recordings, MTWA was considered using three leads (V5, V1, and aVF). Right heart catheterization and 6-minute walk test (6-MWD) were applied to the patients and pro-brain natriuretic peptide levels were assessed; echocardiographic parameters were obtained from both the groups and the results were compared.

Results:

The MTWA value in lead V5 was 81.08±10.73 µV in the patient group (63.50±18.78 µV in the control group), in lead V1 was 75.00±16.86 µV (73.94±16.77 µV in the control group), and in lead aVF was 73.77±17.81 µV (72.61±16.21 µV in the control group). Comparison of MTWA values between patients and controls revealed that only lead V5 values were statistically different in the ES group. The 6-MWD scores significantly correlated with lead V5. Right atrial volume and right ventricular fractional area change were significantly correlated with lead V1. The Tei index was significantly correlated with lead aVF.

Conclusion:

The MTWA lead V5 value was significantly higher in children with ES than in controls and was also correlated with decreased exercise tolerance.

Heart rate and risk of death among patients with Pulmonary Hypertension: A 12-lead ECG analysis

BACKGROUND

Despite the emergence of new therapies, Pulmonary Hypertension (PH) still has a high mortality. Several clinical, echocardiographic, biological or hemodynamic prognostic factors have been identified but are of limited predictive value for survival. We aimed to assess whether heart rate (HR) and all ECG abnormalities measured on a 12-lead ECG may help to better identify patients at high risk of death in this population.

METHODS AND RESULTS

296 patients followed in a registry were included with all types of PH, except group 2 of the WHO clinical classification. After a median follow-up of 10 years, age, male sex, NYHA III/IV status and, among all ECG parameters, HR and corrected QT interval were associated with mortality. In multivariate analysis, HR, age and male sex remained significant independent predictors of mortality. HR has a higher predictive value in the 238 patients in sinus rhythm. In addition, only HR was significantly correlated with clinical and hemodynamic PH prognostic factors.

CONCLUSION

HR measured on a 12-lead ECG at the time of the diagnosis is a strong independent predictor of mortality in PH patients.

Prognostic Relevance of Nonsustained Ventricular Tachycardia in Patients with Pulmonary Hypertension

Background. Increased pulmonary vascular resistance in patients with pulmonary hypertension (PH) leads to an increased afterload of right heart and cardiac remodeling which could provide the substrate or trigger for arrhythmias. Supraventricular arrhythmias were associated with clinical deterioration but were not associated with sudden cardiac death (SCD). SCD has been reported to account for approximately 30% of deaths in patients with pulmonary arterial hypertension (PAH). Objective. The role of nonsustained ventricular tachycardia (nsVT) and its prognostic relevance in patients with PH remains unclear. This study evaluated the prognostic relevance of nsVT in patients with PAH and chronic thromboembolic pulmonary hypertension (CTEPH). Methods. Retrospectively, patients with PAH and CTEPH who underwent Holter ECG monitoring and available data of survival were investigated. Results. Seventy-eight (PAH: 55, CTEPH: 23) patients were evaluated. Holter ECG revealed nsVT in 12 patients. Twenty-one patients died during follow-up. In patients with nsVT, tricuspid annular plane systolic excursion was lower (p = 0.001), and systolic pulmonary arterial pressure was higher (p = 0.163). Mean survival of patients without/with nsVT was 155.2 ± 8.5/146.4 ± 21.4 months (p = 0.690). The association between arrhythmias and survival was not confounded by age (p = 0.681), gender (p = 0.752), 6-MW distance (p = 0.196), or arterial hypertension (p = 0.238). Conclusions. In patients with PH, nsVT occurs more often than previously reported, and patients with PH group 1 seem to be more at risk.

Repolarization Patterns in Congenital Heart Disease

The aim of this study was to study the repolarization patterns in pediatric patients with cyanotic and acyanotic congenital heart diseases as prolonged QT indicates a myocardium at risk of ventricular arrhythmia. A cross-sectional case-control study included 50 patients with acyanotic congenital heart diseases and 50 patients with cyanotic congenital heart diseases who presented to Catheterization Unit of Cairo University Pediatric Hospital between March 2013 and June 2014. We included 50 healthy children as a control. For all the patients' measurement of oxygen saturation, echocardiography and 12-lead electrocardiogram (ECG) were done and the corrected QT (QTc) was measured. The mean QTc was significantly higher in acyanotic congenital heart diseases with volume overload than in control: 0.426 versus 0.4 s (p = 0.009). Increased left ventricular end-diastolic dimension was significantly associated with QTc prolongation (p = 0.01). Early repolarization was higher in congenital heart diseases (18 % in acyanotic patient, 48 % in cyanotic patients) than in control 6 %. Decreased oxygen saturation was significantly associated with early repolarization (p = 0.01). Prolonged QTc was higher in acyanotic congenital heart diseases with volume overload and increased left ventricular end diastolic dimension was a significant association. Decreased oxygen saturation was a significant association.

Predictors of early death in patients with acute pulmonary embolism

AIM

We aimed to determine the predictors of early death in the course of acute pulmonary embolism (APE).

MATERIALS AND METHODS

We included 206 patients who had been admitted to our hospital between January 2011 and April 2013 with the diagnosis of APE. We derived a new model including corrected QT interval dispersion (QTcd) and P wave dispersion (Pd), echocardiographic findings, laboratory markers, and blood cell count indices to predict early death in patients with APE.

RESULTS

Thirty patients (14.5%) died; 176 patients (85.5%) lived after diagnosis of APE. Logistic regression (LR) analysis found that troponin I (odds ratio [OR], 1.084 [95% confidence interval {CI}, 1.009-1.165]), creatinine (OR, 4.153 [95% CI, 1.375-12.541]), mean platelet volume (OR, 1.991 [95% CI, 1.230-3.223]), neutrophil to lymphocyte ratio (NLR) (OR, 1.079 [95% CI, 1.005-1.160]), QTcd (OR, 1.084 [95% CI, 1.043-1.127]), Pd (OR, 1.049 [95% CI, 1.004-1.096]) were associated with early death in APE. New LR model (area under the curve [AUC], 0.970) performed better than the simplified pulmonary embolism severity index (sPESI) score (AUC, 0.859) in predicting early death in APE (P=.021). The predictivity of the sPESI score significantly improved after its single combination with creatinine, QTcd, or troponin I. When the combined model was constructed together with these 6 independent variables and sPESI score, stepwise LR model automatically excluded Pd and NLR, and the AUC from the rest of the combined model was 0.976, which is significantly different from the AUC of sPESI (0.859) (P=.0031).

CONCLUSIONS

Creatinine, troponin I, and QTcd significantly improves sPESI score. A new model with troponin I, creatinine, mean platelet volume, NLR, QTcd, and Pd seems to have greater prognostic power than the sPESI scoring system.

Heart rate variability parameters and ventricular arrhythmia correlate with pulmonary arterial pressure in adult patients with idiopathic pulmonary arterial hypertension

OBJECTIVE

This aim of this study was to correlate heart rate variability (HRV) parameters to pulmonary arterial pressure (PAP) in patients with purely idiopathic pulmonary arterial hypertension (IPAH).

BACKGROUND

HRV is decreased in patients with PAH. Whether HRV indices can be used to assess PAP in IPAH patients remains unclear.

METHODS

HRV parameters obtained by 24-h ECG were evaluated in 26 IPAH patients and 51 controls.

RESULTS

Time-domain HRV parameters (SDNN, p < 0.0001; SDANN, p < 0.0001; RMSSD, p = 0.006) were lower in IPAH patients. Frequency-domain indices (high-frequency power, HFP, p = 0.001; low-frequency power, LFP, p = 0.003; total power, TP, p = 0.001) were also decreased in IPAH patients. In IPAH patients, RMSSD (p = 0.001), HFP (p = 0.015), and LFP (p = 0.027) were significantly correlated with PAP. IPAH patients had longer QTc intervals (p < 0.0001) and more premature ventricular contractions (p < 0.0001) than controls.

CONCLUSIONS

IPAH is associated with autonomic dysfunction. RMSSD, HFP, and LFP may be used as a supplemental tool to assess PAP in IPAH patients. IPAH patients with autonomic dysfunction are at high risk for ventricular arrhythmia.

Macitentan, a dual endothelin receptor antagonist for the treatment of pulmonary arterial hypertension, does not affect cardiac repolarization in healthy subjects

Macitentan is an orally active dual endothelin receptor antagonist, which demonstrated a reduction of the risk of morbidity/mortality events in pulmonary arterial hypertension patients. This double-blind, randomized, placebo- and positive-controlled, four-way crossover thorough QTc study was designed to investigate the effects of therapeutic and supratherapeutic doses of macitentan on cardiac repolarization in healthy male and female subjects. Each subject received the following treatments: moxifloxacin 400 mg, macitentan 10 mg, macitentan 30 mg, and placebo. Each treatment period lasted 9 days and was followed by at least 10 days of washout. The primary endpoint of this study was the baseline-adjusted, placebo-corrected QT interval corrected using the Fridericia method (ΔΔQTcF). Pharmacokinetic (PK), safety, and tolerability assessments were performed during each treatment. A total of 64 subjects were randomized. The upper bound of the 2-sided 90% confidence interval for ΔΔQTcF following macitentan was <10 ms at all time points and no correlation was observed between ΔΔQTcF and PK parameters. Findings in the analysis of the morphological patterns of the ECGs were randomly distributed across all treatments and did not indicate an association with macitentan. Macitentan was well tolerated in this study. Headache and nasopharyngitis were the most frequently reported adverse events. No effects on clinical laboratory and vital signs parameters were observed. In summary, repeated doses of macitentan 10 mg and 30 mg did not indicate any pro-arrhythmic potential.

Electrocardiography at diagnosis and close to the time of death in pulmonary arterial hypertension

BACKGROUND

Scarce information exits on the electrocardiographic (ECG) characteristics of pulmonary arterial hypertension (PAH) patients close to their death and whether observed abnormalities progress from the time of PAH diagnosis.

METHODS

We analyzed the characteristics of the ECG performed at initial diagnosis, during the course of the disease and close to the time of death on consecutive PAH patients followed at our institution between June 2008 and December 2010.

RESULTS

We included 50 patients with PAH (76% women) with mean (SD) age of 58 (14) years. Median heart rate (83 vs 89 bpm, P = 0.001), PR interval (167 vs 176 ms, P = 0.03), QRS duration (88 vs 90 ms, P = 0.02), R/S ratio in lead V1 (1 vs 2, P = 0.01), and QTc duration (431 vs 444 ms, P = 0.02) significantly increased from the initial to the last ECG. In addition, the frontal QRS axis rotated to the right (97 vs 112 degrees, P = 0.003) and we more commonly observed right bundle branch block (5% vs 8%, P = 0.03) and negative T waves in inferior leads (31% vs 60%, P = 0.004). No patient had normal ECG at the time of death.

CONCLUSIONS

Significant changes progressively occur in a variety of ECG parameters between the time of the initial PAH diagnosis and close to death.

Dispersion durations of P-wave and QT interval in children with congenital heart disease and pulmonary arterial hypertension

This study aimed to investigate homogeneity disorders of ventricular repolarization and atrial conduction via QT dispersion and P-wave dispersion in children with congenital heart disease (CHD) and pulmonary arterial hypertension (PAH). Three groups of 20 each were generated and involved in this study. The first group included 20 children with both CHD and PAH. The second group consisted of 20 children with CHD but no PAH, and the third group was composed of 20 age- and sex-matched healthy children. Electrocardiographic records were used to determine P-wave, QT, and corrected QT (QTc) dispersions. The pulmonary hypertension group compared with the group having no pulmonary hypertension and the control group showed a significantly longer P-wave dispersion duration (39.10 ± 9.54 vs. 26.30 ± 4.99 ms, p < 0.001; and 24.80 ± 6.94 ms, p < 0.001, respectively) and QT dispersion duration (52.80 ± 15.11 vs. 37.60 ± 6.00 ms, p < 0.001; and 35.00 ± 7.77 ms, p < 0.001, respectively). In addition, the durations of maximum QTc and QTc dispersion were significantly longer in pulmonary hypertension group than in the other two groups. The risk of atrial and ventricular arrhythmia was found to be increased in the patients with both CHD and PAH. Physicians should pay close attention to possible atrial and ventricular arrhythmias during the treatment and follow-up evaluation of these patients.

Arrhythmias in pulmonary arterial hypertension

Cardiac arrhythmias are important contributors to morbidity and mortality in patients with pulmonary arterial hypertension (PAH). Such patients manifest a substrate resulting from altered autonomics, repolarization abnormalities, and ischemia. Supraventricular arrhythmias such as atrial fibrillation and flutter are associated with worsened outcomes, and maintenance of sinus rhythm is a goal. Sudden death is a relatively common issue, though the contribution of malignant ventricular arrhythmias versus bradyarrhythmias differs from non-PAH patients. Congenital heart disease patients with PAH benefit from catheter ablation of medically refractory arrhythmias. Clinical studies of defibrillator/pacemaker therapy for primary prevention against sudden death in PAH patients are lacking.

Cardiac arrhythmia mechanisms in rats with heart failure induced by pulmonary hypertension

Pulmonary hypertension provokes right heart failure and arrhythmias. Better understanding of the mechanisms underlying these arrhythmias is needed to facilitate new therapeutic approaches for the hypertensive, failing right ventricle (RV). The aim of our study was to identify the mechanisms generating arrhythmias in a model of RV failure induced by pulmonary hypertension. Rats were injected with monocrotaline to induce either RV hypertrophy or failure or with saline (control). ECGs were measured in conscious, unrestrained animals by telemetry. In isolated hearts, electrical activity was measured by optical mapping and myofiber orientation by diffusion tensor-MRI. Sarcoplasmic reticular Ca(2+) handling was studied in single myocytes. Compared with control animals, the T-wave of the ECG was prolonged and in three of seven heart failure animals, prominent T-wave alternans occurred. Discordant action potential (AP) alternans occurred in isolated failing hearts and Ca(2+) transient alternans in failing myocytes. In failing hearts, AP duration and dispersion were increased; conduction velocity and AP restitution were steeper. The latter was intrinsic to failing single myocytes. Failing hearts had greater fiber angle disarray; this correlated with AP duration. Failing myocytes had reduced sarco(endo)plasmic reticular Ca(2+)-ATPase activity, increased sarcoplasmic reticular Ca(2+)-release fraction, and increased Ca(2+) spark leak. In hypertrophied hearts and myocytes, dysfunctional adaptation had begun, but alternans did not develop. We conclude that increased electrical and structural heterogeneity and dysfunctional sarcoplasmic reticular Ca(2+) handling increased the probability of alternans, a proarrhythmic predictor of sudden cardiac death. These mechanisms are potential therapeutic targets for the correction of arrhythmias in hypertensive, failing RVs.

QTc prolongation is associated with impaired right ventricular function and predicts mortality in pulmonary hypertension

BACKGROUND

In rodent models of pulmonary hypertension (PH) and right ventricular hypertrophy (RVH), the QTc interval is prolonged, reflecting downregulation of repolarizing Kv channels in RV myocytes. The significance of QTc prolongation in human PH is unknown. We hypothesized that QTc prolongation occurs in human PH, is associated with RVH and decreased RV function, and predicts adverse prognosis.

METHODS

Patients receiving a PAH-specific therapy (a prostanoid, endothelin-receptor antagonist and/or a phosphodiesterase-5 inhibitor), who had a 12-lead electrocardiogram (ECG) (n=202) were compared to age- and sex-matched controls (n=100). The duration of QTc on ECG was correlated with invasive hemodynamics (n=156) and with the status of the RV, as measured by Brain Natriuretic Peptide (NT-proBNP, n=145) and magnetic resonance imaging (n=24). Survival of the entire PH cohort and a subgroup with WHO Groups 1 and 4 PAH was prospectively determined from the Social Security Death Index.

RESULTS

QTc intervals were longer in PH vs. controls (454.8 ± 29 ms vs. 429.8 ± 18 ms, p<0.001) and did not differ based on PAH-specific therapy. NT-proBNP increased proportionately with QTc and was higher for those in the upper quintile (QTc ≥ 480 ms) vs. those with QTc<480 ms (4004 ± 6682 pg/mL vs. 1501 ± 1822 pg/mL, p<0.001). The QTc interval also correlated directly with increasing RV end-diastolic volume (r=.67, p<0.001) and mass (r=.0.51, p<0.05), and inversely with RV ejection fraction (r=-.49, p<0.05). In the entire PH cohort and WHO Groups 1 and 4 subgroup, QTc ≥ 480 ms and cardiac index were independent predictors of mortality.

CONCLUSIONS

QTc prolongation in PH patients reflects the status of the RV and is an independent predictor of mortality.

Arrhythmogenic substrate in hearts of rats with monocrotaline-induced pulmonary hypertension and right ventricular hypertrophy

Mechanisms associated with right ventricular (RV) hypertension and arrhythmias are less understood than those in the left ventricle (LV). The aim of our study was to investigate whether and by what mechanisms a proarrhythmic substrate exists in a rat model of RV hypertension and hypertrophy. Rats were injected with monocrotaline (MCT; 60 mg/kg) to induce pulmonary artery hypertension or with saline (CON). Myocardial levels of mRNA for genes expressing ion channels were measured by real-time RT-PCR. Monophasic action potential duration (MAPD) was recorded in isolated Langendorff-perfused hearts. MAPD restitution was measured, and arrhythmias were induced by burst stimulation. Twenty-two to twenty-six days after treatment, MCT animals had RV hypertension, hypertrophy, and decreased ejection fractions compared with CON. A greater proportion of MCT hearts developed sustained ventricular tachycardias/fibrillation (0.83 MCT vs. 0.14 CON). MAPD was prolonged in RV and less so in the LV of MCT hearts. There were decreased levels of mRNA for K(+) channels. Restitution curves of MCT RV were steeper than CON RV or either LV. Dispersion of MAPD was greater in MCT hearts and was dependent on stimulation frequency. Computer simulations based on ion channel gene expression closely predicted experimental changes in MAPD and restitution. We have identified a proarrhythmic substrate in the hearts of MCT-treated rats. We conclude that steeper RV electrical restitution and rate-dependant RV-LV action potential duration dispersion may be contributing mechanisms and be implicated in the generation of arrhythmias associated with in RV hypertension and hypertrophy.

QT dispersion in patients with pulmonary embolism

BACKGROUND

Various ECG patterns have been associated with acute pulmonary embolism. However, there is no data regarding the association between QT interval measurements and pulmonary embolism. We aimed to investigate the association between QT dispersion and the severity of pulmonary embolism (PE).

METHODS

One hundred twenty-nine pulmonary embolism patients (mean age 58 ± 16.5 years) with ECGs obtained within the first 24 hours of hospital admission were included in the study. Patients were classified into low, intermediate and high-risk groups. We retrospectively measured ECG scores; maximum and minimum corrected QT intervals (QTc(max) and QTc(min)) and corrected QT interval dispersion (QTcd) in each risk group of patients.

RESULTS

There was an increasing ECG score through from low to high-risk PE [3 (Interquartile Range, IQR: 2), 5 (IQR: 6) and 10 (IQR: 7) p < 0.0001]. QT interval analysis showed that QTcd was higher in high-risk group than in low and intermediate-risk groups (59.5 ± 23.4, 69.2 ± 21, 95.9 ± 33.2, p <0.001 and p = 0.01, respectively). Patients who died after diagnosis had significantly higher QTcd values at baseline compared with the QTcd values of surviving patients (89.1 ± 45.5 to 65 ± 22.9, p = 0.001). The sensitivity of QTcd > 71.5 ms for prediction of mortality was 71% with a specificity of 73% (p = 0.001). We observed a strong correlation between QTcd and ECG score values (r = 0.69, p< 0.001). There was also a correlation between QTcd values and pulmonary artery pressure (PAP) (r = 0.27, p = 0.05).

CONCLUSION

QTcd is significantly increased in high-risk PE patients compared to intermediate and low-risk patients. In addition, QTcd is significantly correlated with ECG score and PAP.

COPD is not COPD is not allergy

Chronic obstructive pulmonary disease (COPD) is still a poorly understood disease. Its pathogenesis is excitingly complex and has systemic consequences caused not only by increased production of certain cytokines but also by neurohumoral activation, chronic bacterial infection, muscle wasting and cachexia. Asthma and COPD have many overlapping clinical features so it should not be surprising that in the pathogenesis of COPD mediators such as leukotrienes, complement activation, atopic or even autoimmune processes are possibly involved. The pathogenesis of cardiovascular system involvement in COPD is also multifaceted and includes chronic heart hypoxia, damage by smoking and pulmonary hypertension; it must also be viewed as a consequence of systemic inflammation and neurohormonal activation. COPD is among the leading causes of morbidity and mortality worldwide and therefore it should be studied intensively beyond the lung itself. Treatments directed at neurohumoral activation in COPD have not been fully addressed; this aspect of COPD should be better understood, as it may direct novel therapeutic approaches.