Increased QT dispersion: a negative prognostic finding in chronic obstructive pulmonary disease

The relationship between frontal QRS-T angle and the severity of newly diagnosed chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterised by persistent airflow restriction and respiratory symptoms. Studies demonstrated that cardiac arrhythmias and cardiovascular mortality increased in these patients as a result of altered myocardial repolarization. Frontal QRS-T angle is a novel marker of myocardial depolarization and repolarization heterogeneity. In this study, we aimed to investigate the relationship between frontal QRS-T angle and disease severity in patients with newly diagnosed COPD.

METHODS

A total of 104 newly diagnosed COPD patients were included in this study. Patients were divided into two groups according to GOLD (Global Obstructive Lung Disease) stage as follows: patients with mild and moderate COPD (group I), and severe and very severe COPD (group II). Frontal QRS-T angle was calculated from the automatic report of the electrocardiography device.

RESULTS

Frontal QRS-T angle was significantly higher in group II patients compared with in group I patients (43.0 [25.5-60.0] vs. 20.0 [12.0-32.0], P < .001). The best cut-off value of frontal QRS-T angle for predicting severe-very severe COPD was ≥34.5°. Correlation analysis showed that frontal QRS-T angle was negatively correlated with FEV1/FVC (r = -.524, P < .001) and MEF25-75 (r = -.453, P < .001). Multivariate logistic regression analysis was showed that frontal QRS-T angle was the only independent predictor of severe-very severe COPD (OR: 1.051, 95% CI: 1.024-1.079, P < .001).

CONCLUSIONS

Frontal QRS-T angle is an easily obtainable marker form surface electrocardiography. In this study, we have shown for the first time that frontal QRS-T angle was significantly increased in patients with severe and very severe COPD.

Nocturnal Heart Rate and Cardiac Repolarization in Lowlanders With Chronic Obstructive Pulmonary Disease at High Altitude: Data From a Randomized, Placebo-Controlled Trial of Nocturnal Oxygen Therapy

Background: Chronic obstructive pulmonary disease (COPD) is associated with cardiovascular disease. We investigated whether sleeping at altitude increases nocturnal heart rate (HR) and other markers of cardiovascular risk or arrhythmias in lowlanders with COPD and whether this can be prevented by nocturnal oxygen therapy (NOT).

Methods: Twenty-four COPD patients, with median age of 66 years and forced expiratory volume in 1 s (FEV₁) 55% predicted, living <800 m underwent sleep studies at Zurich (490 m) and during 2 sojourns of 2 days each at St. Moritz (2,048 m) separated by 2-week washout at <800 m. During nights at 2,048 m, patients received either NOT (2,048 m NOT) or ambient air (2,048 m placebo) 3 L/min via nasal cannula according to a randomized, placebo-controlled crossover trial. Sleep studies comprised ECG and pulse oximetry to measure HR, rhythm, HR-adjusted QT interval (QTc), and mean oxygen saturation (SpO₂).

Results: In the first nights at 490 m, 2,048 m placebo, and 2,048 m NOT, medians (quartiles) of SpO₂ were 92% (90; 94), 86% (83; 89), and 97% (95; 98) and of HR were 73 (66; 82), 82 (71; 85), and 78 bpm (67; 74) (P < 0.05 all respective comparisons). QTc increased from 417 ms (404; 439) at 490 m to 426 ms (405; 440) at 2,048 m placebo (P < 0.05) and was 420 ms (405; 440) at 2,048 m NOT (P = NS vs. 2,048 m placebo). The number of extrabeats and complex arrhythmias was similar over all conditions.

Conclusions: While staying at 2,048 m, lowlanders with COPD experienced nocturnal hypoxemia in association with an increased HR and prolongation of the QTc interval. NOT significantly improved SpO₂ and lowered HR, without changing QTc. Whether oxygen therapy would reduce HR and arrhythmia during longer altitude sojourns remains to be elucidated.

ECG changes at rest and during exercise in lowlanders with COPD travelling to 3100 m

BACKGROUND

The incidence and magnitude of cardiac ischemia and arrhythmias in patients with chronic obstructive pulmonary disease (COPD) during exposure to hypobaric hypoxia is insufficiently studied. We investigated electrocardiogram (ECG) markers of ischemia at rest and during incremental exercise testing (IET) in COPD-patients travelling to 3100 m.

STUDY DESIGN AND METHODS

Lowlanders (residence <800 m) with COPD (forced volume in the first second of expiration (FEV₁) 40-80% predicted, oxygen saturation (SpO₂) ≥92%, arterial partial pressure of carbon dioxide (PaCO₂) <6 kPa at 760 m) aged 18 to 75 years, without history of cardiovascular disease underwent 12‑lead ECG recordings at rest and during cycle IET to exhaustion at 760 m and after acute exposure of 3 h to 3100 m. Mean ST-changes in ECGs averaged over 10s were analyzed for signs of ischemia (≥1 mm horizontal or downsloping ST-segment depression) at rest, peak exercise and 2-min recovery.

RESULTS

80 COPD-patients (51% women, mean ± SD, 56.2 ± 9.6 years, body mass index (BMI) 27.0 ± 4.5 kg/m², SpO₂ 94 ± 2%, FEV₁ 63 ± 10% prEd.) were included. At 3100 m, 2 of 53 (3.8%) patients revealed ≥1 mm horizontal ST-depression during IET vs 0 of 64 at 760 m (p = 0.203). Multivariable mixed regression revealed minor but significant ST-depressions associated with altitude, peak exercise or recovery and rate pressure product (RPP) in multiple leads.

CONCLUSION

In this study, ECG recordings at rest and during IET in COPD-patients do not suggest an increased incidence of signs of ischemia with ascent to 3100 m. Whether statistically significant ST changes below the standard threshold of clinical relevance detected in multiple leads reflect a risk of ischemia during prolonged exposure remains to be elucidated.

An association between right ventricular dysfunction and sudden cardiac death

BACKGROUND

The effectiveness of severely reduced left ventricular ejection fraction (LVEF <35%) as a predictor of sudden cardiac death (SCD) has diminished, and improvements in risk stratification await discovery of novel markers. Right ventricular (RV) abnormalities can be observed in conditions such as chronic obstructive pulmonary disease and sleep apnea, which have been linked to SCD.

OBJECTIVE

The purpose of this study was to evaluate whether RV abnormalities were associated with SCD after accounting for LVEF and other patient characteristics.

METHODS

In a large, prospective ongoing community-based study of SCD in the Portland, Oregon, metropolitan area, SCD cases (age ≥18 years; 2002-2014) were compared to controls with coronary artery disease but no SCD. Using a novel archive of digital echocardiograms, a standardized approach was used to evaluate RV basal diameter, RV end-diastolic area, and right ventricular fractional area change (RVFAC).

RESULTS

A total of 350 subjects were studied, including 81 SCD cases (age 68.7 ± 13.6 years; 73% male) and 269 controls (age 66.5 ± 10.2 years; 69% male). In multivariate analysis, RVFAC was significantly associated with SCD (odds ratio 1.14 for each 5% decrease; 95% confidence interval 1.03-1.25; P = .01). When modeled with LVEF ≤35%, RVFAC ≤35% was significantly associated with increased risk of SCD. Individuals with both left ventricular and RV dysfunction had a 3× higher odds of SCD than those with neither (odds ratio 3.19; 95% confidence interval 1.33-7.68; P = .01).

CONCLUSION

RV dysfunction was associated with a significantly increased risk of SCD independent of LVEF and, when combined with LVEF, had additive effects on SCD risk.

The relationship between systolic pulmonary arterial pressure and Tp-e interval, Tp-e/QT, and Tp-e/QTc ratios in patients with newly diagnosed chronic obstructive pulmonary disease

INTRODUCTION

The risk of sudden cardiac death (SCD) and arrhythmias has been shown to be common in chronic obstructive pulmonary disease (COPD) subjects. We aimed to evaluate the markers of arrhythmia such as QT, QTc (corrected QT), Tp-e, and cTp-e (corrected Tp-e) intervals, Tp-e/QT ratio, and Tp-e/QTc ratio in newly diagnosed COPD subjects in both right and left precordial leads.

MATERIALS AND METHODS

The study group consisted of 74 subjects with obstructive respiratory function tests (RFTs). The control group consisted of 78 subjects who had nonobstructive RFTs. RFTs, electrocardiograms (ECG), and transthoracic echocardiograms (TTE) were performed, and QTR (QT interval in right precordial leads), QTL (QT interval in left precordial leads), Tp-eR (Tp-e interval in right precordial leads), and Tp-eL (Tp-e interval in left precordial leads) intervals; systolic pulmonary arterial pressure (sPAP); forced expiratory volume in one second (FEV₁ )/forced vital capacity (FVC); and peripheral oxygen saturation(POS) values were measured.

RESULTS

Tp-eR interval 85.82 ± 5.34 millisecond (ms) versus 62.87 ± 3.55 ms (t = 31.29/p < .00001), cTp-eR interval 97.51 ± 7.18 ms versus 71.07 ± 4.58 ms (t = 27.20/p < .00001), Tp-eR/QTR ratio 0.234 ± 0.02 versus 0.164 ± 0.01 (t = 2.2/p = .014), and Tp-eR/QTcR ratio 0.201 ± 0.01 versus 0.141 ± 0.01 (t = 1.92/p = .028) were statistically significantly higher in COPD subjects. There was a strong negative correlation between RFT and sPAP (sPAP, 29.93 ± 5.1 mm Hg; and FEV₁ /FVC, 63.78 ± 3.33%, r = -.85/p < .00001). There was a moderate positive correlation between sPAP and Tp-eR.

CONCLUSION

We found Tp-e and cTp-e intervals, Tp-e/QT ratio, and Tp-e/QTc ratio were significantly higher in the COPD patients than in the control group. In addition, in the COPD group, heart rate variability (HRV) parameters were significantly lower on ECG.

Long QT and death in hospitalized patients with acute exacerbation of chronic obstructive pulmonary disease is not related to electrolyte disorders

Objectives: COPD is the fourth-leading cause of mortality worldwide. Prolonged QTc has been found to be a long-term negative prognostic factor in ambulatory COPD patients. The aim of this study was to evaluate the extent of prolonged-QTc syndrome in COPD patients upon admission to an internal medicine department, its relationship to hypomagnesemia, hypokalemia, and hypocalcemia, and the effect of COPD treatment on mortality during hospital stay.

Methods: This prospective cohort study evaluated COPD patients hospitalized in an internal medicine department. The study evaluated QTc, electrolyte levels, and known risk factors during hospitalization of COPD patients.

Results: A total of 67 patients were recruited. The median QTc interval was 0.441 seconds and 0.434 seconds on days 0 and 3, respectively. Prolonged QTc was noted in 35.8% of patients on admission and 37.3% on day 3 of hospitalization. The median QTc in the prolonged-QTc group on admission was 0.471 seconds and in the normal-QTc group 0.430 seconds. There was no significant difference in age, sex, electrolyte levels, renal function tests, or blood gases on admission between the two groups. Mortality during the hospital stay was significantly higher in the prolonged-QTc group (3 deaths, 12%) than in the normal QTc group (no deaths) (P=0.04). A subanalysis was performed, removing known causes for prolonged QTc. We found no differences in age, electrolytes, or renal functions. There was a small but significant difference in bicarbonate levels.

Conclusion: Our findings demonstrated that there was no correlation between QTc prolongation in hospitalized COPD patients and electrolyte levels, comorbidities, or relevant medications. A higher rate of mortality was noted in patients with prolonged QTc in comparison to normal QTc. As such, it is suggested that prolonged QTc could serve as a negative prognostic factor for mortality during hospitalization in COPD patients.

Continuous remote monitoring of COPD patients-justification and explanation of the requirements and a survey of the available technologies

Remote patient monitoring should reduce mortality rates, improve care, and reduce costs. We present an overview of the available technologies for the remote monitoring of chronic obstructive pulmonary disease (COPD) patients, together with the most important medical information regarding COPD in a language that is adapted for engineers. Our aim is to bridge the gap between the technical and medical worlds and to facilitate and motivate future research in the field. We also present a justification, motivation, and explanation of how to monitor the most important parameters for COPD patients, together with pointers for the challenges that remain. Additionally, we propose and justify the importance of electrocardiograms (ECGs) and the arterial carbon dioxide partial pressure (PaCO2) as two crucial physiological parameters that have not been used so far to any great extent in the monitoring of COPD patients. We cover four possibilities for the remote monitoring of COPD patients: continuous monitoring during normal daily activities for the prediction and early detection of exacerbations and life-threatening events, monitoring during the home treatment of mild exacerbations, monitoring oxygen therapy applications, and monitoring exercise. We also present and discuss the current approaches to decision support at remote locations and list the normal and pathological values/ranges for all the relevant physiological parameters. The paper concludes with our insights into the future developments and remaining challenges for improvements to continuous remote monitoring systems. Graphical abstract ᅟ.

Increased QT dispersion is associated with reduced overall survival in patients with acute exacerbations of chronic obstructive pulmonary disease

OBJECTIVES

Chronic obstructive pulmonary disease (COPD), especially acute exacerbations of COPD, are associated with increased cardiovascular mortality, including sudden cardiac death. Previous studies have reported that ECG abnormalities are common in stable COPD patients. However, the prognostic utility of ECG taken at the time of AECOPD is not known. In this study we sought to address this gap in knowledge pertaining to ECG parameters at time of AECOPD and overall survival.

METHODS

We conducted a retrospective cohort study of patients admitted to our institution with a primary diagnosis of AECOPD. Standard 12-lead ECG obtained at the time of initial presentation was evaluated. The primary outcome was overall survival.

RESULTS

Two hundred and eleven AECOPD patients were considered for the study. Death had occurred in 42 (20%) patients at follow-up. Among the different ECG parameters evaluated, the QT Dispersion (QTD) and corrected QT Dispersion (QTcD) were significantly associated with increased mortality. Receiver Operator Characteristic analysis identified QTcD >48msec had a sensitivity of 90% and specificity of 55% in predicting death and QTcD >48msec was also associated with worse overall survival (months) (mean ± SD: 26 ± 1.0 vs. 30 ± 0.7, p = 0.001).

CONCLUSION

QTcD ≥48msec is associated with increased mortality. Further research is required to better understand this association and potentially identify reversible factors that if appropriately addressed, may ultimately improve the prognosis of patients with COPD.

Lung function, percent emphysema, and QT duration: The Multi-Ethnic Study of Atherosclerosis (MESA) lung study

BACKGROUND

The QT interval on electrocardiogram (ECG) reflects ventricular repolarization; a prolonged QT interval is associated with increased mortality risk. Prior studies suggest an association between chronic obstructive pulmonary disease (COPD) and prolonged QT interval. However, these studies were small and often enrolled hospital-based samples. We tested the hypotheses that lower lung function and increased percent emphysema on computed tomography (CT) are associated with a prolonged QT interval in a general population sample and additionally in those with COPD.

METHODS

As part of the Multi-Ethnic Study of Atherosclerosis (MESA) Lung Study, we assessed spirometry, full-lung CT scans, and ECGs in participants aged 45-84 years. The QT on ECGs was corrected for heart rate (QTc) using the Framingham formula. QTc values = 460 msec in women and ≥450 msec in men were considered abnormal (prolonged QT_C). Multivariate regression models were used to examine the cross-sectional association between pulmonary measures and QT_C. RESULTS: The mean age of the sample of 2585 participants was 69 years, and 47% were men. There was an inverse association between FEV₁%, FVC%, FEV₁/FVC%, emphysema, QTc duration and prolonged QTc. Gender was a significant interaction term, even among never smokers. Having severe COPD was also associated with QTc prolongation.

CONCLUSIONS

Our analysis revealed a significant association between lower lung function and longer QTc in men but not in women in a population-based sample. Our findings suggest the possibility of gender differences in the risk of QTc-associated arrhythmias in a population-based sample.

Chronic Obstructive Pulmonary Disease and Risk of Sudden Cardiac Death

OBJECTIVES

The purpose of this study was to determine whether chronic obstructive pulmonary disease (COPD) is associated with sudden cardiac death (SCD) in the community.

BACKGROUND

COPD is linked to cardiovascular mortality; an association with SCD has not been systematically investigated in the general population.

METHODS

In the Oregon Sudden Unexpected Death Study (approximately 1 million population), adult SCD case subjects were compared with geographic control subjects with coronary artery disease. Detailed clinical and electrocardiographic risk marker information was obtained from medical records. The association of COPD with SCD in the overall population and in a propensity score-matched dataset was assessed with logistic models.

RESULTS

SCD case subjects (n = 728; age 69.9 ± 13.7 years) were more likely than control subjects (n = 548; age 67.2 ± 11.3 years) to have left ventricular ejection fraction ≤35% (27.5% vs. 12.0%; p < 0.0001), COPD (30.8% vs. 12.8%, p < 0.0001), diabetes mellitus (47.7% vs. 31.8%; p < 0.0001), use short-acting beta-2 agonist agents (SBAs) (22.3% vs. 12.6%; p < 0.0001), and less likely to use beta-blockers (60.6% vs. 66.4%; p = 0.03). In multivariable analysis, COPD was significantly associated with SCD (odds ratio [OR]: 2.2; 95% confidence interval [CI]: 1.4 to 3.5; p < 0.001). There was no significant interaction between COPD and medications, but an interaction was identified between SBAs and beta-blockers (p = 0.04); SBAs were strongly associated with SCD in subjects not taking beta-blockers (OR: 3.3; 95% CI: 1.4 to 7.7; p = 0.005) but not in those taking beta-blockers (OR: 1.3; 95% CI: 0.7 to 2.3; p = 0.39). The COPD-SCD association was maintained in a propensity score-matched analysis.

CONCLUSIONS

COPD is associated with SCD risk in the community independent of medications, electrocardiographic risk markers, and left ventricular ejection fraction. Among other mechanisms, pro-arrhythmogenic right ventricular remodeling and systemic inflammation warrant further investigation.

High prevalence of altered cardiac repolarization in patients with COPD

BACKGROUND

Altered cardiac repolarization and increased dispersion of repolarization have been identified as risk factors for sudden cardiac death (SCD). The prevalence of and the mechanisms contributing to altered cardiac repolarization are currently unknown in COPD.

METHODS

In 91 COPD patients, 32 controls matched for age, cardiovascular risk and medication, and 41 healthy subjects, measures of cardiac repolarization and dispersion of repolarization (QTc interval, QT dispersion) were derived from 12-lead electrocardiography (ECG). Prevalence rates of heart rate corrected QT (QTc) >450ms and QT dispersion >60ms were determined to assess the number of subjects at risk for SCD. Univariate and multivariate analyses were used to identify possible factors contributing to altered cardiac repolarization.

RESULTS

QTc was found to be prolonged in 31.9% and QT dispersion in 24.2% of the COPD patients compared to 12.5% in matched controls and 0% in healthy subjects. The QTc interval was longer in COPD patients compared to matched and healthy controls respectively (437.9 ± 29.5 vs. 420.1 ± 25.3 ms, p = 0.001 and vs. 413.4 ± 18.2 ms, p < 0.001). QT dispersion was significantly increased in COPD patients compared to healthy subjects (45.4 (34.8 , 59.5) vs. 39.7 (29.3 , 54.8) ms, p = 0.049). Only oxygen saturation was independently associated with QTc duration in multivariate analysis (β = -0.29, p = 0.015).

CONCLUSION

One third of a typical COPD population has altered cardiac repolarization and increased dispersion of repolarization, which may be related to hypoxia. Altered cardiac repolarization may expose these patients to an increased risk for malignant ventricular arrhythmias and SCD.

Heart rate-corrected QT interval predicts mortality in glyphosate-surfactant herbicide-poisoned patients

BACKGROUND

Glyphosate-surfactant herbicide is promoted by the manufacturer as having no risks to human health. Glyphosate surfactant has recently been used with increasing frequency in suicide attempts, so clinical toxicologists occasionally encounter cases of severe systemic toxicity. The purpose of this study was to identify the early predictive factors of patients at risk for mortality and the usefulness of the corrected QT interval (QTc interval) for predicting mortality from glyphosate-surfactant intoxication.

METHODS

This was a retrospective cohort study conducted from January 2005 to December 2012. A total of 153 patients with acute glyphosate-surfactant ingestion were included. To identify the predictive factors for mortality, objective variables easily assessed at presentation including previously reported predictive factors for mortality and severity were retrospectively analyzed for their association with mortality using univariate and multiple logistic analyses.

RESULTS

The average age of the patients was 56 years (range, 19-93 years). Of the 153 patients, 19 (12.4%) died. The most common abnormal electrocardiogram findings were prolonged QTc interval followed by intraventricular conduction delay and first-degree atrioventricular block. Nonsurvivors had a significantly more prolonged QTc interval when compared with that of survivors (survivors: 453.4 ± 33.6 milliseconds vs nonsurvivors: 542 ± 32.0 milliseconds, P < .001). Corrected QT interval and age were associated with a significantly increased risk of death in a multiple logistic regression. In a receiver operating curve analysis, the QTc interval had significant discriminatory power.

CONCLUSION

Prolonged QTc interval seems to be a useful prognostic factor for mortality in patients intoxicated with glyphosate-surfactant herbicide.

Arrhythmias as trigger for acute exacerbations of chronic obstructive pulmonary disease

PURPOSE

Acute exacerbations of chronic obstructive pulmonary disease (COPD) sometimes appear to occur without a precipitating cause. Heterogeneous repolarization and arrhythmias occur in COPD patients. Given the close inter-relation between heart and lung, we hypothesized that unrecognized arrhythmias might be precipitants of acute exacerbations.

METHODS

Electrocardiograms (ECG) of thirty patients during acute exacerbations were compared with ECG during stable phase. P wave dispersion was used to assess atrial depolarization heterogeneity, and dispersion of QT interval to assess ventricular repolarization. p < 0.05 was considered significant. Frequent exacerbations were defined as two or more exacerbations in a year.

RESULTS

Mean age of patients was 70.3 ± 11.8 SD years. P wave dispersion was greater during acute exacerbation than during stable phase (56.7 ± 19.2 vs 47.7 ± 15.9 ms, p = 0.009). There was a trend toward greater QTc dispersion (108.3 ± 61.7 vs 90.3 ± 47.0 ms, p = 0.13) in acute exacerbation compared to stable phase. Sixteen (53%) had frequent exacerbations. There was a significant difference in PR interval during stable phase between those with frequent exacerbations and those without (163.9 + 17.4 vs. 145.1 + 22.8; p = 0.02). The P wave dispersion during stable phase was greater in those with frequent exacerbations, but did not reach statistical significance (52.6 + 18.8 vs. 42.2 + 9.8 ms; p = 0.06).

CONCLUSIONS

P wave dispersion is more in the acute phase than in stable phase, and is greater in patients with more frequent exacerbations. This does not prove, but suggests an intriguing possibility that P wave dispersion predates acute exacerbations. This might be a new target for prediction, prevention and therapy of acute exacerbations of COPD.

Heart rate-corrected QT interval helps predict mortality after intentional organophosphate poisoning

Introduction

In this study, we investigated the outcomes for patients with intentional organophosphate poisoning. Previous reports indicate that in contrast to normal heart rate-corrected QT intervals (QTc), QTc prolongation might be indicative of a poor prognosis for patients exposed to organophosphates.

Methods

We analyzed the records of 118 patients who were referred to Chang Gung Memorial Hospital for management of organophosphate poisoning between 2000 and 2011. Patients were grouped according to their initial QTc interval, i.e., normal (<0.44 s) or prolonged (>0.44 s). Demographic, clinical, laboratory, and mortality data were obtained for analysis.

Results

The incidence of hypotension in patients with prolonged QTc intervals was higher than that in the patients with normal QTc intervals (P = 0.019). By the end of the study, 18 of 118 (15.2%) patients had died, including 3 of 75 (4.0%) patients with normal QTc intervals and 15 of 43 (34.9%) patients with prolonged QTc intervals. Using multivariate-Cox-regression analysis, we found that hypotension (OR = 10.930, 95% CI = 2.961–40.345, P = 0.000), respiratory failure (OR = 4.867, 95% CI = 1.062–22.301, P = 0.042), coma (OR = 3.482, 95% CI = 1.184–10.238, P = 0.023), and QTc prolongation (OR = 7.459, 95% CI = 2.053–27.099, P = 0.002) were significant risk factors for mortality. Furthermore, it was revealed that non-survivors not only had longer QTc interval (503.00±41.56 versus 432.71±51.21 ms, P = 0.002), but also suffered higher incidences of hypotension (83.3 versus 12.0%, P = 0.000), shortness of breath (64 versus 94.4%, P = 0.010), bronchorrhea (55 versus 94.4%, P = 0.002), bronchospasm (50.0 versus 94.4%, P = 0.000), respiratory failure (94.4 versus 43.0%, P = 0.000) and coma (66.7 versus 11.0%, P = 0.000) than survivors. Finally, Kaplan-Meier analysis demonstrated that cumulative mortality was higher among patients with prolonged QTc intervals than among those with normal QTc intervals (Log-rank test, Chi-square test = 20.36, P<0.001).

Conclusions

QTc interval helps predict mortality after intentional organophosphate poisoning.

Factors associated with mortality in patients with exacerbation of chronic obstructive pulmonary disease hospitalized in General Medicine departments

We aim to improve knowledge on risk factors that relate to mortality in subjects with exacerbation of chronic obstructive pulmonary disease (COPD) who are hospitalized in General Medicine departments. In a cross-sectional multicenter study, by means of a logistic regression analysis, we assessed the possible association of death during hospitalization with the following groups of variables of participating patients: sociodemographic features, treatment received prior to admission and during hospitalization, COPD-related clinical features recorded prior to admission, comorbidity diagnosed prior to admission, clinical data recorded during hospitalization, laboratory results recorded during hospitalization, and electrocardiographic findings recorded during hospitalization. A total of 398 patients was included; 353 (88.7%) were male, and the median age of the patients was 75 years. Of these patients, 21 (5.3%) died during hospitalization. Only 270 (67.8%) received inhaled β(2) agonists during hospitalization, while 162 (40.7%) received angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers. The median of predicted FEV(1) prior to admission was 42%. A total of 350 patients (87.9%) had been diagnosed with two or more comorbid conditions prior to admission. An association was found between increased risk of death during hospitalization and the previous diagnoses of pneumonia, coronary heart disease, and stroke. In conclusion, comorbidity is an important contributor to mortality among patients hospitalized in General Medicine departments because of COPD exacerbation.

Prolonged QTc interval in children and young adults with sickle cell disease at steady state

BACKGROUND

Prolongation of the QTc interval may be more common than previously believed among individuals with sickle cell disease (SCD). The clinical associations and natural history of QTc prolongation remain unclear in this population. Our objectives were to determine the prevalence of prolonged QTc and evaluate its relationship to clinical factors in children and young adults with SCD.

PROCEDURES

We analyzed data from subjects 10 to 25 years old with SCD enrolled in our pulmonary hypertension screening protocol. Screening included echocardiography (ECHO), 12-lead electrocardiogram (ECG) and laboratory testing at steady state. QTc interval >440 msec was considered prolonged.

RESULTS

ECG data from 76 subjects (57% male, mean age 14.2 +/- 3 years old, range 10-24) were analyzed. We observed prolonged QTc in 29/76 (38%) subjects. Despite evidence of left ventricular hypertrophy (LVH) in 50/76 (66%) subjects, the frequency of LVH was not significantly different in subjects with and without QTc prolongation. When compared to subjects with normal QTc, subjects with prolonged QTc had higher mean tricuspid regurgitant jet velocity (2.51 +/- 0.27 m/sec vs. 2.33 +/- 0.26 m/sec, P = 0.010) as well as higher mean lactate dehydrogenase (433 +/- 142 IU/L vs. 343 +/- 142 IU/L, P = 0.000) and aspartate aminotransferase (48 +/- 20 IU/L vs. 39 +/- 15 IU/L, P = 0.026). A larger proportion of subjects with prolonged QTc also had a history of recurrent acute chest syndrome (66% vs. 38%, P = 0.038).

CONCLUSIONS

We conclude that QTc prolongation is a frequent finding in SCD not associated with LVH. Elevated pulmonary pressures, hemolysis and acute chest syndrome may represent risk factors for prolonged QTc in this population.