Systolic blood pressure but not electrocardiogram QRS duration is associated with heart rate variability (HRV): a cross-sectional study in rural Australian non-diabetics.

BACKGROUND: A positive correlation between ECG derived QRS duration and heart rate variability (HRV) parameters had previously been reported in young healthy adults. We note this study used a narrow QRS duration range, and did not adjust for systolic blood pressure. Our aims are to investigate associations between systolic blood pressure (SBP), QRS duration and HRV in a rural aging population. METHODS: A retrospective cross sectional population was obtained from the CSU Diabetes Screening Research Initiative data base where 200 participants had no diabetes or pre-diabetes. SBP data were matched with ECG derived QRS duration and HRV parameters. HRV parameters were calculated from R-R intervals. Resting 12-lead electrocardiograms were obtained from each subject using a Welch Allyn PC-Based ECG system. RESULTS: Pearson correlation analysis revealed no statistically significant associations between HRV parameters and QRS duration. No significant mean differences in HRV parameter subgroups across defined QRS cut-offs were found. SBP > 146 mmHg was associated with increasing QRS durations, however this association disappeared once models were adjusted for age and gender. SBP was also significantly associated with a number of HRV parameters using Pearson correlation analysis, including high frequency (HF) (p < 0.05), HFln (p < 0.02), RMSDD (p < 0.02) and non-linear parameters; ApEN (p < 0.001) were negatively correlated with increasing SBP while the low frequency to high frequency ratio (LF/HF) increased with increasing SBP (p < 0.03). CONCLUSIONS: Our results do not support associations between ECG derived R-R derived HRV parameters and QRS duration in aging populations. We suggest that ventricular conduction as determined by QRS duration is independent of variations in SA-node heart rate variability.

Management of rheumatoid arthritis in clinical practice using treat-to-target strategy: Where do we stand in the multi-ethnic Malaysia population?

To evaluate the achievement of treat-to-target (T2T) strategy in rheumatoid arthritis (RA) and identify factors associated with failed treatment target in a public rheumatology center. A cross-sectional study was conducted from June 2015 to February 2016. RA patients with disease duration greater than 2 years and under T2T for over a year were invited to the study. Demographic, clinical data, disease activity score of 28 joints (DAS28), and clinical disease activity index (CDAI) were collected in a single routine clinic visit. Treatment target was defined as DAS28 <3.2 or CDAI ≤10. Retrospective chart review was performed to determine reasons of failed treatment target. A total of 371 patients were recruited and 87.1% were female. Mean age and duration of RA were 53.5 years (SD 10.3) and 9.1 years (SD 6.6), respectively. Ethnic distribution was 49% Chinese, 27% Malay, and 24% Indian. T2T was achieved in 81.7% of the cohort. Non-Chinese ethnicity, positive rheumatoid factor, and treatment with three disease modifying anti-rheumatic drugs (DMARDs) were associated with failed treatment target. After controlling for covariates, Malay ethnicity (OR 2.96; 95% CI 1.47-5.96) and treatment with three DMARDs (OR 2.14; 95% CI 1.06-4.35) were associated with failed treatment target. There was no association between age, gender, duration of RA, BMI, smoking status, anti-citrulinated cyclic peptide, and achievement of T2T. The most common reasons of failed treatment target were inability to escalate DMARDs due to side effects (18.8%), lack of biologics fund (15.6%), and persistent disease despite optimum treatment (14.1%). T2T was successfully implemented. Malay patients need aggressive treatment adaptation to achieve optimal outcome.

The association of uncoupling protein 2 (UCP2) exon 8 insertion/deletion polymorphism and ECG derived QRS duration: A cross-sectional study in an Australian rural population.

BACKGROUND: Associations between inherited mitochondrial disease and cardiac conduction have been previously described. However, there are no available studies exploring the mitochondrial uncoupling protein 2 gene (UCP2) insertion/deletion (I/D) polymorphisms interaction on cardiac electrical conduction. Our aim was to determine if ECG-derived QRS duration is associated with UCP2 DD genotype in a cross-sectional Australian aging rural population. METHODS: A retrospective study design utilizing a rural health diabetic screening clinic data-base containing observational data from September 2011 to September 2014. Inclusion criteria included were having ECG parameters such as QRS duration measures and a DNA sample within the same subject. Genomic DNA was extracted and subjects were genotyped for the 45-bp I/D polymorphism in the 3'-untranslated region of UCP2. RESULTS: 281 individuals were available for analysis. On the basis of QRS duration >140ms we found an increased percentage of our population with DD homozygotes, compared to ID heterozygotes and II homozygotes (p=0.047). For other ECG parameters; mean PQ duration, QTc across UCP2 genotypes was not significant (p=NS). QTc using a cut-off >440ms in contingency table analysis revealed no significant differences across UCP2 I/D genotypes. Mean QT dispersion (QTd) was paradoxically less in the UCP2 DD genotype compared to UCP2 II subgroup (p=0.034). DISCUSSION: We have demonstrated an association between increasing ECG-derived QRS duration >140ms and the UCP2 DD polymorphism. The lack of association with ECG derived QTd and UCP2 DD may suggest that gene-related QRS duration prolongation is independent of cardiac hypertrophy.

Electrocardiogram derived QRS duration associations with elevated central aortic systolic pressure (CASP) in a rural Australian population.

BACKGROUND: Prolonged electrocardiogram QRS durations are often present in hypertensive patients. Small increases in QRS duration serve as independent risk factors for both increased cardiovascular and all-cause mortality. Aortic stiffness is associated with increases in central aortic systolic blood pressure (CASP). However CASP and ECG QRS duration interactions have not been established in rural community populations. Our aims are to determine if QRS duration > 100 msec is associated with an elevated CASP measure in an Australian rural population. METHODS: A retrospective cross sectional population was obtained from the CSU Diabetes Screening Research Initiative data base where 68 participants had both central aortic pressure recorded and ECG derived QRS duration. Central aortic pressure was determined by directly recording radial arterial tonometry and brachial cuff pressure (HealthStats, Singapore). Resting 12-lead electrocardiograms were obtained from each subject using a Welch Allyn PC-Based ECG system. RESULTS: The population had a mean CASP of 137.8 mmHg, higher than previously reported in other population studies. In 8/68 subjects with a prolonged cardiac QRS duration >120 msec, CASP ranged from 129 mmHg - 182 mmHg. When subgroup analysis was stratified on the basis QRS duration <100 msec and ≥100 msec significant differences (p = 0.036) were observed for mean CASP, 130.6 mmHg ± 15.6 (SD) versus 140.6 mmHg ± 16.8 (SD), respectively. CONCLUSIONS: Our results suggest that an arbitrary CASP reading greater than a value 140 mmHg raises suspicion of a prolonged QRS duration. QRS durations ≥100 msec in an aging rural population are associated with higher CASP measures. Our results also suggest in aging Australian rural populations CASP is likely to be elevated, possibly due to age related aortic stiffening.