Smart devices to measure and monitor QT intervals.

Careful observation of the QT interval is important to monitor patients with long QT syndrome and during treatment with potentially QT-prolonging medication. It is also crucial in the development of novel drugs, in particular in case of a potential side effect of QT prolongation and in patients with increased risk of QT prolongation. The 12-lead electrocardiogram (ECG) is the gold standard to evaluate cardiac conduction and repolarization times. Smartwatches and smart devices offer possibilities for ambulatory ECG recording and therefore measuring and monitoring the QT interval. We performed a systematic review of studies on smartwatches and smart devices for QTc analysis. We reviewed PubMed for smartwatches and smart devices that can measure and monitor the QT interval. A total of 31 studies were included. The most frequent devices were (1) KardiaMobile 6L, a Food and Drug Administration-approved device for QTc analyses that provides a 6-lead ECG, (2) an Apple Watch, a smartwatch with an integrated ECG tool that allows recording of a single-lead ECG, and (3) the Withings Move ECG ScanWatch, an analog watch with a built-in single-lead ECG. The KardiaMobile 6L device and the Apple Watch provide accurate measurements of the QT interval, although the Apple Watch is studied in standard and non-standard positions, and the accuracy of QT measurements increased when the smartwatch was moved to alternative positions. Most studies were performed on patients, and limited results were available from healthy volunteers.

Selective testing for thrombophilia in patients with first venous thrombosis: results from a retrospective family cohort study on absolute thrombotic risk for currently known thrombophilic defects in 2479 relatives.

Thrombophilia screening is controversial. In a retrospective family cohort, where probands had thrombosis and a thrombophilic defect, 2479 relatives were tested for thrombophilia. In antithrombin-, protein C-, and protein S-deficient relatives, annual incidences of venous thrombosis were 1.77% (95% CI, 1.14-2.60), 1.52% (95% CI, 1.06-2.11), and 1.90% (95% CI, 1.32-2.64), respectively, at a median age of 29 years and a positive family history of more than 20% symptomatic relatives. In relatives with factor V (FV) Leiden, prothrombin 20210G>A, or high FVIII levels, these were 0.49% (95% CI, 0.39-0.60), 0.34% (95% CI, 0.22-0.49), and 0.49% (95% CI, 0.41-0.51), respectively. High FIX, FXI, and TAFI, and hyperhomocysteinemia were not independent risk factors. Annual incidence of major bleeding in antithrombin-, protein C-, or protein S-deficient relatives on anticoagulants was 0.29% (95% CI, 0.03-1.04). Cumulative recurrence rates in relatives with antithrombin, protein C, or protein S deficiency were 19% at 2 years, 40% at 5 years, and 55% at 10 years. In relatives with FV Leiden, prothrombin 20210G>A, or high levels FVIII, these were 7%, 11%, and 25%, respectively. Considering its clinical implications, thrombophilia testing should address hereditary deficiencies of antithrombin, protein C, and protein S in patients with first venous thrombosis at young age and/or a strong family history of venous thrombosis.

Hereditary deficiency of protein C or protein S confers increased risk of arterial thromboembolic events at a young age: results from a large family cohort study.

BACKGROUND: Whether hereditary protein S, protein C, or antithrombin deficiency is associated with arterial thromboembolism (ATE) and whether history of venous thromboembolism in these subjects predisposes them to subsequent ATE have yet to be determined. METHODS AND RESULTS: On the basis of pedigree analysis, we enrolled a total of 552 subjects (52% women; mean age, 46+/-17 years), belonging to 84 different kindreds, in this retrospective family cohort study. Detailed information on previous episodes of venous thromboembolism, ATE, anticoagulant use, and atherosclerosis risk factors was collected. Primary study outcome was objectively verified symptomatic ATE. Of 552 subjects, 308 had protein S (35%), protein C (39%), or antithrombin (26%) deficiency. Overall, annual incidences of ATE were 0.34% (95% confidence interval [CI], 0.23 to 0.49) in deficient versus 0.17% (95% CI, 0.09 to 0.28) in nondeficient subjects; the hazard ratio was 2.3 (95% CI, 1.2 to 4.5). Because the risk hazards varied over lifetime, we performed a time-dependent analysis. After adjusting for atherosclerosis risk factors and clustering within families, we found that deficient subjects had a 4.7-fold (95% CI, 1.5 to 14.2; P=0.007) higher risk for ATE before 55 years of age versus 1.1 (95% CI, 0.5 to 2.6) thereafter compared with nondeficient family members. For separate deficiencies, the risks were 4.6- (95% CI, 1.1 to 18.3), 6.9- (95% CI, 2.1 to 22.2), and 1.1- (95% CI, 0.1 to 10.9) fold higher in protein S-, protein C-, and antithrombin-deficient subjects, respectively, before 55 years of age. History of venous thromboembolism was not related to subsequent ATE (hazard ratio, 1.1; 95% CI, 0.5 to 2.2). CONCLUSIONS: Compared with nondeficient family members, subjects with protein S or protein C deficiency but not antithrombin deficiency have a higher risk for ATE before 55 years of age that is independent of prior venous thromboembolism.

High absolute risks and predictors of venous and arterial thromboembolic events in patients with nephrotic syndrome: results from a large retrospective cohort study.

BACKGROUND: No data are available on the absolute risk of either venous thromboembolism (VTE) or arterial thromboembolism (ATE) in patients with nephrotic syndrome. Reported risks are based on multiple case reports and small studies with mostly short-term follow-up. We assessed the absolute risk of VTE and ATE in a large, single-center, retrospective cohort study and attempted to identify predictive factors in these patients. METHODS AND RESULTS: A total of 298 consecutive patients with nephrotic syndrome (59% men; mean age, 42+/-18 years) were enrolled. Mean follow-up was 10+/-9 years. Nephrotic syndrome was defined by proteinuria > or =3.5 g/d, and patients were classified according to underlying histological lesions accounting for nephrotic syndrome. Objectively verified symptomatic thromboembolic events were the primary study outcome. Annual incidences of VTE and ATE were 1.02% (95% confidence interval, 0.68 to 1.46) and 1.48% (95% confidence interval, 1.07 to 1.99), respectively. Over the first 6 months of follow-up, these rates were 9.85% and 5.52%, respectively. Proteinuria and serum albumin levels tended to be related to VTE; however, only the predictive value of the ratio of proteinuria to serum albumin was significant (hazard ratio, 5.6; 95% confidence interval, 1.2 to 26.2; P=0.03). In contrast, neither the degree of proteinuria nor serum albumin levels were related to ATE. Sex, age, hypertension, diabetes, smoking, prior ATE, and estimated glomerular filtration rate predicted ATE (P< or =0.02). CONCLUSIONS: This study verifies high absolute risks of symptomatic VTE and ATE that were remarkably elevated within the first 6 months. Whereas the ratio of proteinuria to serum albumin predicted VTE, estimated glomerular filtration rate and multiple classic risk factors for atherosclerosis were predictors of ATE.

High long-term absolute risk of recurrent venous thromboembolism in patients with hereditary deficiencies of protein S, protein C or antithrombin.

Hereditary deficiencies of protein S, protein C and antithrombin are known risk factors for first venous thromboembolism. We assessed the absolute risk of recurrence, and the contribution of concomitant thrombophilic defects in a large cohort of families with these deficiencies. Annual incidence of recurrence was estimated in 130 deficient patients, with separate estimates for those with each of protein S, protein C, and antithrombin deficiency, and in eight non-deficient patients with prior venous thromboembolism. All patients were also tested for factor V Leiden, prothrombin G20210A, high levels of factors VIII, IX and XI, and hyperhomocysteinemia. There were 81 recurrent events among 130 deficient patients. Median follow-up was 4.6 years. Annual incidences (95% confidence interval) of recurrent venous thromboembolism were 8.4% (5.8-11.7) for protein S deficiency, 6.0% (3.9-8.7) for protein C deficiency, 10.0% (6.1-15.4) for antithrombin deficiency, and overall 7.7% (6.1-9.5). Relative risk of recurrence in patients with a spontaneous versus provoked first event was 1.5 (0.95-2.3). Cumulative recurrence rates at 1, 5 and 10 years were 15%, 38% and 53%. Relative risk of recurrence with concomitant defects was 1.4 (0.7-2.6) (1 defect) and 1.4 (0.8-2.7) (> or =2 defects). Annual incidence was 1.0% (0.03-5.5) in eight non-deficient patients. Annual incidence of major bleeding in deficient patients on oral anticoagulant treatment was 0.5% (0.2-1.0). We conclude that patients with a hereditary protein S, protein C or antithrombin deficiency appear to have a high absolute risk of recurrence. This risk is increased after a first spontaneous event, and by concomitance of other thrombophilic defects.

Oral contraceptives and the absolute risk of venous thromboembolism in women with single or multiple thrombophilic defects: results from a retrospective family cohort study.

BACKGROUND: The risk of venous thromboembolism (VTE) in women taking combined oral contraceptives (COCs) is attributed to changes in coagulation and fibrinolysis. Their impact may be greater in women with preexistent thrombophilic defects. METHODS: We assessed the effects of COCs on absolute VTE risk in women with single or multiple thrombophilic defects in a retrospective family cohort study. Female relatives of probands with VTE and hereditary deficiencies of protein S, protein C, or antithrombin were tested for known thrombophilic defects, including the index deficiency. Absolute incidences of VTE were compared in deficient vs nondeficient women, in deficient and nondeficient women who ever or never used COCs, and in deficient and nondeficient women with 0, 1, or more than 1 other thrombophilic defect during exposure to COCs. RESULTS: Of 222 women, 135 (61%) ever used COCs. Overall, annual incidences of VTE were 1.64% and 0.18% in deficient and nondeficient women, respectively; the adjusted relative risk was 11.9 (95% confidence interval, 3.9-36.2). The risk was comparable in deficient ever and never users (1.73% vs 1.54%). Annual incidences during actual COC use were 4.62% in deficient women and 0.48% in nondeficient women; the relative risk was 9.7 (95% confidence interval, 3.0-42.4). The incidence increased by concomitant thrombophilic defects, from 3.49% to 12.00% in deficient women and from 0% to 3.13% in nondeficient women. CONCLUSIONS: Women with hereditary deficiencies of protein S, protein C, or antithrombin are at high risk of VTE during use of COCs, particularly when other thrombophilic defects are present. They have VTE at a younger age, but the overall risk is not increased by COCs.

The risk of venous and arterial thrombosis in hyperhomocysteinemic subjects may be a result of elevated factor VIII levels.

In a large retrospective study of thrombophilic families, we analyzed 405 relatives of patients, hypothesizing that hyperhomocysteinemia and elevated factor VIII levels are closely related. Median factor VIII levels in hyperhomocysteinemic relatives were 169 IU/dL, compared with 136 IU/dL in normohomocysteinemic relatives (p =0.007), and were more often elevated (>150 IU/dL; p =0.006). Hyperhomocysteinemia was associated with an increased risk of venous and arterial thrombosis; relative risk (RR) 2.6 (CI 1.3-4.8) and 3.7 (CI 1.5-8.4) respectively. Relatives with elevated FVIII were also at risk; RR 2.3 (CI 1.4-4.0) for venous thrombosis and 2.3 (CI 1.0-5.1) for arterial thrombosis. After excluding all relatives with elevated factor VIII, RR for hyperhomocysteinemia and venous thrombosis dropped to 1.3 (CI 0.2-9.8) and no relatives had arterial thrombosis. We conclude that it is likely that the increased risk of venous and arterial thrombosis in hyperhomocysteinemia is mainly related to elevated FVIII levels.

Contribution of multiple thrombophilic and transient risk factors in the development of cerebral venous thrombosis.

INTRODUCTION: Cerebral venous thrombosis (CVT), deep vein thrombosis (DVT) and/or pulmonary embolism (PE) have been associated with thrombophilic defects. However, in contrast to DVT or PE, CVT is a rare disease. We performed a study to identify differences in thrombotic risk profile, predisposing to CVT rather than DVT or PE, particularly the contribution of oral contraception and 11 thrombophilic defects. MATERIALS AND METHODS: A single center case-control study (63 CVT cases and 209 controls with DVT or PE) was performed. RESULTS: Of CVT patients, 11% had experienced prior DVT or PE, and none had recurrent CVT at 5 years follow-up. CVT was more frequently observed in females (79% versus 51%, P<0.001). It was more often secondary (75% versus 50%, P<0.001), mainly due to the difference in age between both groups. At presentation of CVT and DVT/PE, oral contraceptives were used by 78% and 74% of non-pregnant fertile women (P=0.8), respectively. Any thrombophilic defect was demonstrated in 88% of CVT and 75% of DVT/PE patients (P=0.22), sex and age matched. Individual and two or more defects were equally distributed among both groups. CONCLUSIONS: We conclude that a majority of CVT and DVT or PE patients show single or multiple thrombophilic defects. At presentation, oral contraceptive intake was observed more frequently in CVT patients. However, no differences were observed in thrombotic risk profile between both groups of comparable age. Hence, additional unknown risk factors should be considered to explain the different sites of thrombosis in these patients.

The pathogenesis of venous thromboembolism: evidence for multiple interrelated causes.

BACKGROUND: Venous thromboembolism (VTE) is thought to result from interactions between multiple genetic and environmental risk factors. OBJECTIVE: To assess the contribution of multiple thrombophilic defects and exogenous risk factors to the absolute risk for VTE. DESIGN: Retrospective family cohort study. SETTING: Single university hospital. PARTICIPANTS: 468 relatives of 91 probands with a symptomatic hereditary deficiency of protein S, protein C, or antithrombin. MEASUREMENTS: All relatives were tested for 10 thrombophilic deficiencies and defects in addition to the index deficiency and were assessed for exogenous risk factors (surgery, trauma, immobilization, use of oral contraceptives, and pregnancy). The authors compared annual incidences and relative risks for VTE in deficient and nondeficient relatives. RESULTS: Annual incidences of VTE in relatives with 0, 1, and 2 or more additional thrombophilic deficiencies or defects were 1.16 (95% CI, 0.60 to 2.03), 1.75 (CI, 1.17 to 2.53), and 2.64 (CI, 1.67 to 3.96) per 100 person-years, respectively, compared with 0.06 (CI, 0.002 to 0.33) per 100 person-years in nondeficient relatives without additional deficiencies or defects. Adjusted relative risks were 16.3 (CI, 2.0 to 131.0), 50.3 (6.5 to 389.7), and 102.8 (12.5 to 843.4). Of deficient relatives, 38% with no additional defect, 57% with 1 additional defect, and 81% with 2 or more additional defects had VTE at age 65 years compared with 5% of nondeficient relatives (P < 0.001). In deficient relatives with additional deficiencies or defects, exogenous risk factors increased the risk for VTE from 1.20% to 2.51% per year (relative risk, 2.1 [CI, 1.1 to 4.2]). LIMITATIONS: This was a retrospective study without the ability to distinguish interactions between specific thrombophilic deficiencies and defects. CONCLUSION: Additional thrombophilic defects and exogenous risk factors increase the risk for VTE in persons with hereditary deficiencies of protein S, protein C, or antithrombin and provide evidence that multiple genetic and environmental risk factors contribute to VTE.

Identification of a novel PROS1 c.1113T-->GG frameshift mutation in a family with mixed type I/type III protein S deficiency.

We report a family with type I and type III protein S (PS) deficiency, which showed to be phenotypic variants of the same genetic disease. Direct sequencing analysis of the PROS1 gene was performed to establish the genotype. The ratio of protein C antigen and total PS antigen levels (protein C/S ratio) was used to classify subjects at risk of venous thromboembolism. All PS deficient subjects had increased protein C/S ratios as well as a novel PROS1 c.1113T-->GG frameshift mutation.

Interaction of Hereditary Thrombophilia and Traditional Cardiovascular Risk Factors on the Risk of Arterial Thromboembolism: Pooled Analysis of Four Family Cohort Studies.

BACKGROUND: Hereditary thrombophilia is associated with a slightly increased risk of arterial thromboembolism (ATE). Whether hereditary thrombophilia interacts with traditional cardiovascular risk factors on the risk of ATE has yet to be established. METHODS AND RESULTS: A total of 1891 individuals belonging to 4 family cohorts from the Netherlands were included in the analyses. Five hereditary thrombophilic defects, including factor V Leiden, prothrombin G20210A defect, and deficiencies of the natural anticoagulants (ie, antithrombin, protein C, and protein S), were assessed, and data on risk factors and previous ATE were collected. Thrombophilia was associated with elevated risk of ATE (hazard ratio =1.74, 95% confidence interval, 1.18-2.58; P=0.005). Overall, the association of thrombophilia with ATE tended to be stronger in the presence of traditional cardiovascular risk factors, especially the synergistic effect of thrombophilia with diabetes mellitus was striking (hazard ratio of thrombophilia-ATE association was 1.41 in nondiabetics versus 8.11 in diabetics). Moreover, the association of thrombophilia with ATE tended to be stronger in females and before the age of 55 years as compared with males and individuals >55 years of age, respectively. CONCLUSIONS: Thrombophilia is associated with ATE. This association may be stronger in the presence of traditional cardiovascular risk factors in particular in individuals with diabetes mellitus. Future studies on thrombophilia-ATE risk should focus on high-risk populations with high prevalence of traditional cardiovascular risk factors.

Reduction of high fetal loss rate by anticoagulant treatment during pregnancy in antithrombin, protein C or protein S deficient women.

Hereditary thrombophilia is associated with an increased risk of fetal loss. Assuming that fetal loss is due to placental thrombosis, anticoagulant treatment might improve pregnancy outcome. In an observational family cohort study, we prospectively assessed the effects of anticoagulant drugs on fetal loss rates in women with hereditary deficiencies of antithrombin, protein C or protein S. The cohort contained 376 women (50 probands and 326 deficient or non-deficient relatives). Probands were consecutive deficient patients with venous tromboembolism. Thromboprophylaxis during pregnancy was recommended in deficient women, irrespective of prior venous thromboembolism, and in non-deficient women with prior venous thromboembolism. Outcome of first pregnancy was analysed in 55 eligible women. Of 37 deficient women, 26 (70%) received thromboprophylaxis during pregnancy, compared with three of 18 (17%) non-deficient women. Fetal loss rates were 0% in deficient women with thromboprophylaxis versus 45% in deficient women without (P = 0.001) and 7% in non-deficient women without thromboprophylaxis (P = 0.37). The adjusted relative risk of fetal loss in women who received thromboprophylaxis versus women who did not was 0.07 (95% confidence interval 0.001-0.7; P = 0.02). Our data suggest that anticoagulant treatment during pregnancy reduces the high fetal loss rate in women with hereditary deficiencies of antithrombin, protein C or protein S.

High risk of pregnancy-related venous thromboembolism in women with multiple thrombophilic defects.

Pregnancy is associated with an increased risk of venous thromboembolism, which probably varies according to the presence of single or multiple thrombophilic defects. This retrospective family cohort study assessed the risk of venous thromboembolism during pregnancy and puerperium, and the contribution of concomitant thrombophilic defects in families with hereditary antithrombin, protein C or protein S deficiencies. Probands were excluded. Of 222 female relatives, 101 were deficient and 121 non-deficient. Annual incidences of venous thromboembolism were 1.76% in deficient women versus 0.19% in non-deficient women [adjusted relative risk (RR) 11.9; 95% confidence interval (CI), 3.9-36.2]. Other single and multiple thrombophilic defects increased the risk in deficient women from 1.55% to 2.14% and 2.92%, and in non-deficient women from 0.16% to 0.09% and 0.54% respectively. Deficient women were at lower risk (1.37%; 0.80-2.19) than deficient women that had never been pregnant (2.96%; 1.53-5.18); RR 0.5 (0.2-0.99). This difference was due to the predominance of events related to oral contraceptives in deficient women that had never been pregnant (75%), while 71% of events in deficient women that had had at least one pregnancy were pregnancy-related. In conclusion, women with hereditary deficiencies of antithrombin, protein C or protein S are at high risk of pregnancy-related venous thromboembolism. This risk is increased by multiple additional thrombophilic defects.

Difference in absolute risk of venous and arterial thrombosis between familial protein S deficiency type I and type III. Results from a family cohort study to assess the clinical impact of a laboratory test-based classification.

Hereditary protein S (PS) deficiency type I is an established risk factor for venous thromboembolism. Contradictionary data on type III deficiency suggests a difference in risk between both types. We studied 156 first degree relatives (90% of eligible relatives) from type I deficient probands (cohort 1) and 268 (88%) from type III deficient probands (cohort 2) to determine the absolute risk of venous and arterial thromboembolism. Annual incidences of venous thromboembolism were 1.47 and 0.17 per 100 person-years in deficient and non-deficient relatives in cohort 1 [relative risk (RR) 8.9; 95% confidence interval (CI) 2.6-30.0], and 0.27 vs. 0.24 in cohort 2 (RR 0.9; 95% CI 0.4-2.2). Type III deficiency was demonstrated in 20% of non-deficient relatives in cohort 1 and the annual incidence in this subgroup was 0.70 (RR 4.3;0.95-19.0). The cut-off level of free PS to identify subjects at risk was 30%, the lower limit of its normal range (65%). PS deficiency was not a risk factor for arterial thromboembolism. In conclusion, type I deficiency was found to be a strong risk factor for venous thromboembolism, in contrast with type III deficiency. This was because of lower free PS levels in type I deficient subjects and a free PS cut-off level far below the lower limit of its normal range.

The contribution of inherited and acquired thrombophilic defects, alone or combined with antiphospholipid antibodies, to venous and arterial thromboembolism in patients with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is associated with an increased risk of venous (VTE) and arterial thromboembolism (ATE). Lupus anticoagulant (LA) and anticardiolipin antibodies (ACAs) are established risk factors. We assessed the contribution of deficiencies of antithrombin, protein C, total protein S, factor V Leiden, the prothrombin G20210A mutation and APC resistance, either alone or in various combinations with LA and/or ACAs, to the thrombotic risk in a cohort of 144 consecutive patients with SLE. Median follow-up was 12.7 years. VTE had occurred in 10% and ATE in 11% of patients. LA,ACAs, factor V Leiden, and the prothrombin mutation were identified as risk factors for VTE. Annual incidences of VTE were 2.01 (0.74-4.37) in patients with one of these disorders and 3.05 (0.63-8.93) in patients with 2 disorders. The risk of VTE was 20- and 30-fold higher, respectively, compared with the normal population. In contrast with LA and ACAs, thrombophilic disorders did not influence the risk of ATE. In conclusion, factor V Leiden and the prothrombin mutation contribute to the risk of VTE in patients with SLE, and potentiate this risk when one of these thrombophilic defects are combined with LA and/or ACAs.

Development and validation of a health-related quality-of-life questionnaire in patients with yellow jacket allergy.

BACKGROUND: The effects of an anaphylactic reaction after a yellow jacket sting on health-related quality of life (HRQL) have not been studied and are thus unknown. OBJECTIVE: Development of a disease-specific instrument to measure HRQL in patients with yellow jacket allergy and validation of this instrument both cross-sectionally and longitudinally. METHODS: Quality-of-life items were generated from patient interviews. Items with the highest impact were considered and correlated cross-sectionally with an independent measure (consisting of 2 questions in which patients were asked what they expected would happen if they were stung again, "Expectation of Outcome" questionnaire). Cross-sectional and longitudinal validation was achieved by administering this instrument to 69 Dutch patients. The questionnaire was also administered to 50 patients with yellow jacket allergy in Baltimore, Maryland, to establish cross-sectional validity of the English version. RESULTS: The survey showed that patients experienced impairment in quality of life especially because of emotional distress. The resultant questionnaire has 14 items. The cross-sectional validation yielded a correlation coefficient of 0.69 for the Dutch version and 0.56 for the English version. The longitudinal validation yielded a correlation coefficient of 0.71. The responsiveness of this instrument was demonstrated by the questionnaire's ability to detect changes over time. It may be completed in approximately 10 minutes by patients without assistance. CONCLUSION: Patients with yellow jacket allergy experience impairment in quality of life especially because of emotional distress. It has been possible to develop and validate a questionnaire (the Vespid Allergy Quality of Life Questionnaire) by which the HRQL of these patients can be measured. The instrument may be administered rapidly and is easy to use.