The prognostic value of the frontal QRS-T angle is comparable to cardiovascular autonomic neuropathy regarding long-term mortality in people with diabetes. A population based study.

Cardiovascular autonomic neuropathy (CAN) is a well known prognostic marker in diabetes. A large angle between the QRS- and the T-wave vector (QRS-T angle) in the electrocardiogram (ECG) has recently been introduced as another marker of poor prognosis. AIM: To assess and compare the long-term predictive power of the frontal plane QRS-T angle with CAN in people with diabetes. METHODS: In 1992-93 people with diabetes in the municipality of Horsens, Denmark, were identified by the prescription method andan age and gender stratified sample of 240 individuals with diabetes were randomly selected. The presence of CAN was defined using the heart rate response to Valsalva manoeuvre. The QRS-T angle was read using the method described by Gandhi. In July 2015 vital statistics were obtained fromthe Danish Civil Registration System. RESULTS: 178 individuals accepted to participate in the study, of which 153 (86%) completed the Valsalva manoeuvre and had sinus rhythm. Total observation time was 21.5 (0.18) years, in which 99 (65%) individuals died. An elevated QRS-T angle and the presence of cardiovascular autonomic neuropathy were both found to be significant predictors of death. In Cox regression analyses, adjusting for the effect of gender, age, duration of diabetes, BMI, total-cholesterol, diabetes type, haemoglobin A1c, smoking status, hypertension and previous MI, an independent prognostic value was found for the QRS-T angle as well as the Valsalva ratio. CONCLUSION: A large QRS-T angle and the presence of cardiovascular autonomic neuropathy are both strong and independent long-term predictors of all-cause mortality in people with diabetes.

Endothelial dysfunction, increased inflammation, and activated coagulation in HIV-infected patients improve after initiation of highly active antiretroviral therapy.

OBJECTIVES: Endothelial dysfunction and inflammation have been demonstrated to be markers of cardiovascular risk. We investigated the effects of HIV infection per se and the antiretroviral treatment prescribed on the levels of risk factors of cardiovascular disease. METHODS: This was a prospective study of 20 treatment-naïve, nonsmoking, HIV-positive patients examined before and after 3 months of treatment with a protease inhibitor (PI)-containing regimen followed by 3 months of treatment with nonnucleoside reverse transcriptase inhibitor (NNRTI)-containing therapy. Parameters of inflammation, endothelial function and coagulation were examined. The results were compared with those for an age- and gender-matched, nonsmoking, healthy control group. RESULTS: Compared with controls, treatment-naïve HIV-infected patients exhibited endothelial dysfunction [flow-mediated dilation (FMD) 108 vs. 111% for HIV-infected vs. control groups, respectively; P < 0.05] and activation [von Willebrand factor 2.0 vs. 0.9 U/l; soluble intercellular adhesion molecule (sICAM) 313 vs. 211 ng/L, respectively; P < 0.01]. Inflammation [C-reactive protein (CRP) 24 vs. 8.6 nmol/L; fibrinogen 9.4 vs. 8.6 µmol/L, respectively; P < 0.05] and coagulation/fibrinolysis (D-dimers 0.55 vs. 0.23 µg/mL, respectively; P < 0.01) were increased. Initiating therapy resulted in normalization of FMD and a significant decrease in endothelial activation and CRP. CONCLUSION: Endothelial dysfunction together with increased inflammation and coagulation were more prevalent in untreated HIV-infected patients compared with controls. These cardiovascular risk factors improved with treatment, although not all parameters normalized after 6 months.

Effects of metoprolol on QT interval and QT dispersion in Type 1 diabetic patients with abnormal albuminuria.

AIMS/HYPOTHESIS: The excess mortality in diabetes is mainly due to cardiovascular causes and almost confined to patients with abnormal albuminuria. Compared to healthy subjects, diabetic patients have a prolonged QT interval and increased QT dispersion. In non-diabetic subjects, as well as in Type 1 diabetic patients with overt nephropathy, a prolonged QT interval and increased QT dispersion are associated with cardiac morbidity and mortality. There is an increasing number of studies on effects of beta blocker treatment on QT interval and QT dispersion in non-diabetic subjects. In contrast, there are no studies on the effects of beta blocker treatment on QT interval and QT dispersion in patients with diabetes. The aim of our study was to describe the effects of metoprolol treatment on QT interval and QT dispersion in a group of well-characterised Type 1 diabetic patients with elevated urine albumin excretion. METHODS: We studied the effects of 6 weeks of treatment with metoprolol (100 mg once daily, zero order kinetics formulation) in a randomised, placebo-controlled, double blind, crossover trial including 20 Type 1 diabetic patients. Patients were simultaneously monitored under ambulatory conditions with 24-h Holter-monitoring, 24-h ambulatory blood pressure recording and 24-h fractionated urine collections. On days of investigation 12-lead electrocardiograms were recorded and autonomic tests performed. RESULTS: We found strong associations between both daytime and night-time blood pressure and heart-rate-corrected QT interval dispersion (QTc dispersion). Heart rate variability parameters indicating sympathetic and parasympathetic modulation showed strong correlations with heart-rate-corrected QT interval (QTc interval) and with QTc dispersion. Beta blocker treatment caused a decrease in QTc interval but no change in QTc dispersion. CONCLUSIONS/INTERPRETATION: This study is the first to address the QTc interval and QTc dispersion in Type 1 diabetic patients treated with metoprolol. Beta blocker treatment caused a decrease in QTc interval but no change in QTc dispersion. These results may in part explain the pronounced cardioprotective effect of beta blocker treatment in diabetic patients with cardiovascular disease.

Increased QTc dispersion is related to blunted circadian blood pressure variation in normoalbuminuric type 1 diabetic patients.

A reduced nocturnal fall in blood pressure (BP) and increased QT dispersion both predict an increased risk of cardiovascular events in diabetic as well as nondiabetic subjects. The relationship between these two parameters remains unclear. The role of diabetic autonomic neuropathy in both QT dispersion and circadian BP variation has been proposed, but data have been conflicting. The aim of the present study was to describe associations between QT dispersion and circadian BP variation as well as autonomic function in type 1 diabetic patients. In 106 normoalbuminuric (urinary albumin excretion <20 microg/min) normotensive patients, we performed 24-h ambulatory BP (Spacelabs 90207) and short-term (three times in 5 min) power spectral analysis of RR interval oscillations, as well as cardiovascular reflex tests (deep breathing test, postural heart rate, and BP response). No patient had received (or had earlier received) antihypertensive or other medical treatment apart from insulin. In a resting 12-lead electrocardiogram, the QT interval was measured by the tangent method in all leads with well-defined T-waves. The measurement was made by one observer blinded to other data. The QT interval was corrected for heart rate using Bazett's formula. The QTc dispersion was defined as the difference between the maximum and the minimum QTc interval in any of the 12 leads. When comparing patients with QTc dispersion below and above the median (43 ms), the latter had significantly higher night BP (114/67 vs. 109/62 mmHg, P < 0.003/P < 0.001), whereas day BP was comparable (129/81 vs. 127/79 mmHg). Diurnal BP variation was blunted in the group with QTc dispersion >43 ms with significantly higher night/day ratio, both for systolic (88.8 vs. 86.2%, P < 0.01) and diastolic (83.1 vs. 79.5%, P < 0.01) BP. The association between QTc dispersion and diastolic night BP persisted after controlling for potential confounders such as sex, age, duration of diabetes, urinary albumin excretion, and HbA1c. Power spectral analysis suggested an altered sympathovagal balance in patients with QTc dispersion above the median (ratio of low-frequency/high-frequency power: 1.0 vs. 0.85, P < 0.01). In normoalbuminuric type 1 diabetic patients, increased QTc dispersion is associated with reduced nocturnal fall in BP and an altered sympathovagal balance. This coexistence may be operative in the ability of these parameters to predict cardiovascular events.

Bias of QT dispersion.

BACKGROUND: Prolonged QT dispersion (QTD) is associated with an increased risk of arrhythmic death but its accuracy varies substantially between otherwise similar studies. This study describes a new type of bias that can explain some of these differences. MATERIAL: One dataset (DiaSet) consisted of 356 subjects: 169 with diabetes, 187 nondiabetic control persons. Another dataset (ArrSet) consisted of 110 subjects with remote myocardial infarction: 55 with no history of arrhythmia and 55 with a recent history of ventricular tachycardia or fibrillation. METHODS: 12-lead surface ECGs were recorded with an amplification of 10 mm/mV at a paper speed of 50 mm/s. The QT interval was measured manually by the tangent-method. The bias depends on the magnitude of the measurement errors and the measurable part of the bias increases with the number of the repeated measurements of QT. RESULTS: The measurable bias was significant for both datasets and decreased for increasing QTD in the DiaSet (P < 0.001) and in the ArrSet (P = 0.11). The bias was 2.5 ms and 1.9 ms at QTD = 38 ms and 68 ms, respectively, in the ArrSet, and 7.5 ms and 2.8 ms at QTD = 19 ms and 55 ms, respectively, in the DiaSet. CONCLUSIONS: This study shows that random measurement errors of QT introduces a type of bias in QTD that decreases as the dispersion increases, thus reducing the separation between patients with low versus high dispersion. The bias can also explain some of the differences in the mean QTD between studies of healthy populations. Averaging QT over three successive beats reduces the bias efficiently.

Reproducibility of QT parameters derived from 24-hour ambulatory ECG recordings in healthy subjects.

AIM: To estimate the reproducibility of QT parameters derived from 24-hour ambulatory ECG recordings. METHOD: Ten healthy volunteers aged 25 to 41 years participated. In two 24-hour ambulatory ECG recordings obtained 1 day apart, the QT interval was measured manually at stable heart rates in approximately 16 periods during daytime and 6 periods during nighttime. The association between the QT and RR interval was described by linear regression for day and nighttime separately and the following QT parameters were calculated: the QT interval at heart rate 60 beats/min during daytime (QT(60)day), slope(day), slope(night), and the difference in QT(60) between day and nighttime (DeltaQT(60)). The QT parameters were assessed four times for each participant to discriminate method inaccuracy from day to day variation. The reproducibility was estimated as the coefficient of repeatability, the relative error, and the ratio between within-subject variability and between-subject variability. RESULTS: The coefficient of repeatability, the relative error and the ratio, respectively, were 19 ms, 1.8% and 0.5 for QT(60)day, 0.076, 21% and 0.68 for slope(day), 0.116, 43% and 1.37 for slope(night), and 37 ms, 325% and 1.19 for DeltaQT(60) when estimating the overall day to day reproducibility. Inaccuracy of QT measurement accounted for approximately 40% of this variation, whereas the error caused by selecting segments was small. CONCLUSION: QT(60)day has a high reproducibility and may with advantage replace the conventional QT interval measured on a resting ECG. To assess QT dynamics, the slope of the regression line during daytime is suitable and the short term reproducibility acceptable for clinical trials. Regarding slope(night) and DeltaQT(60), the variation is high and the parameters should be used with caution.

[St Jude's bi-leaflet aortic valve prosthesis throughout two decades. Quality profile and risk factors]. / St. Judes dobbeltskive-aortaklapprotese igennem to årtier. Kvalitetsprofil og risikofaktorer.

INTRODUCTION: The St Jude standard aortic bi-leaflet disc valve is still the most widespread. With almost 20 years of follow-up, the present material may describe the quality profile of the valve and the relevant risk factors throughout the remainder of most patients' lives. MATERIAL AND METHODS: A 100% complete follow-up was conducted of 694 adult patients who had an aortic valve replacement with the St Jude valve during 1980-1993. The Cox regression analysis was used to identify independent risk factors. RESULTS: Survival was 79%, 58%, 39%, and 37% at 5, 10, 15, and 18 years, respectively. Only 12% of the deaths (0.60%/patient-year) were valve-related with a 15-year freedom of 91%. Embolism (1.18%/patient-year) and anticoagulant-related bleeding (2.24%/patient-year) were the dominant complications with 15-year freedoms of 80% and 72%. Valve thrombosis was noted in two patients (0.04%/patient-year) who were off anticoagulation. Mechanical failure was not observed. Endocarditis (0.42%/patient-year) had a 15-year freedom of 92% compared with 72% and 54%, respectively, for major valve (2.33%/patient-year) and all valve-related complications together (4.33%/patient-year) and 96% for aortic valve reoperation (0.36%/patient-year). Age of the patient and heart-related variables were identified as independent risk factors for mortality and valve-related complications. CONCLUSION: With a follow-up of almost two decades showing a low incidence of valve-related deaths, acceptable thrombogenicity, and absence of mechanical failure, the St Jude bi-leaflet aortic disc valve sets the standard for contemporary mechanical valves.

Assessing cardiovascular autonomic neuropathy in diabetes mellitus: how many tests to use?

The aim was to evaluate the relative importance of an established battery of five function tests used in the assessment of cardiovascular autonomic neuropathy (CAN) in diabetes employing spectral analysis of heart rate variability (HRV) as the reference test. In a population-based sample of 178 diabetic persons and 194 non-diabetic controls, five function tests (E/I ratio, Valsalva, 30:15 ratio, Orthostatic-BP, and sustained Handgrip) and power spectral analysis of a 24-h Holter recording were carried out. The high-frequency power during nighttime (LnHF(NIGHT)) was taken to express the parasympathetic function and the daytime low-frequency power (LnLF(DAY)) to express the sympathetic function. The readings were log transformation when appropriate, age-corrected, and standardized to units of standard deviation. Combinations of the three mainly parasympathetic tests and the two mainly sympathetic tests were computed by averaging the standardized readings. A high value of the mean sum of squares in LnHF(NIGHT) or LnLF(DAY) - explained in regression analysis - was assumed to represent the better test or combination of tests. The three parasympathetic function tests each correlated significantly to LnHF(NIGHT). The E/I ratio had a correlation to LnHF(NIGHT) similar to the combination of the three parasympathetic tests and the combination of all five function tests, whereas Valsalva and 30:15 ratio had a significantly poorer association. Sustained Handgrip-correlated significantly poorer to LnLF(DAY) compared to Orthostatic BP and the combination of the two sympathetic tests explained a significantly smaller part of the variation in LnLF(DAY) and LnHF(NIGHT) than did the combination of all five tests. This study indicates that: (1) no information is gained by adding the sympathetic function tests to the parasympathetic tests, (2) the most informative test is the E/I ratio, (3) and knowledge about the degree of CAN as defined by reduced HRV is not significantly increased when the four other function tests assessed are added to the E/I ratio.

Standard aortic St. Jude valve at 18 years: performance profile and determinants of outcome.

BACKGROUND: The standard St. Jude disc valve has been in use for 20 years and remains the dominant mechanical valve of today. With nearly 19 years of follow-up, the present large series could indicate the performance profile and its determinants in the very long term. METHODS: A detailed follow-up was performed to a maximum of 18.6 years in 694 patients aged 15 to 83 years who undervent aortic valve replacement (AVR) with the standard St. Jude valve during 1980 to 1993. The Cox regression analysis was used to identify independent determinants of outcome in the aortic stenosis (n = 490) and regurgitation (n = 204) groups. RESULTS: Overall survival was 58%, 39%, and 37% at 10, 15, and 18 years, respectively. Only 12% of deaths (0.60%/ patient-year) were related to the valve with a 15-year freedom of 91%. Embolism (1.18%/patient-year) and anticoagulant-related bleeding (2.24%/patient-year) were the dominant complications with 10-year/15-year freedoms of 90%/80% and 85%/72%, respectively. Only 24% of bleeding events were classified as major. Valve thrombosis occurred in 2 patients (0.04%/patient-year): 1 did not receive vitamin K antagonist treatment and International Normalized Ratio was below target level in the other. There were no mechanical failures. Endocarditis (0.42%/patient-year) and paravalvular leak (0.42%/ patient-year) occurred with 15-year freedoms of 92% and 96%, respectively, with a relation between the latter (but not the former) and preoperative endocarditis in the regurgitation group. Freedom from serious complications (2.33%/patient-year) and all complications joined (4.33%/ patient-year) were 72% and 54%, respectively, at 15 years with a 96% freedom from redo AVR (0.36%/patient-year). Age- and heart-related variables were independent risk factors for mortality, thromboembolism, bleeding, serious complications, and all complications joined. Small valve (19 and 21 mm) adversely affected serious and all complications in the regurgitation group. CONCLUSIONS: With a follow-up approaching 2 decades and exhibiting a low rate of valve-related deaths, acceptable low thrombogenicity, and absence of mechanical failure, the standard aortic St. Jude disc valve sets the standard for contemporary mechanical valves.

Cardiovascular autonomic neuropathy in insulin-dependent diabetes mellitus: prevalence and estimated risk of coronary heart disease in the general population.

OBJECTIVES: The aim of the study was to estimate the prevalence of cardiovascular autonomic neuropathy (CAN) in Type 1 diabetes mellitus in the general population and to assess the relationship between CAN and risk of future coronary heart disease (CHD). METHODS: The Type 1 diabetes mellitus population in the municipality of Horsens, Denmark, was delineated by the prescription method and a random sample of 120 diabetics aged 40-75 years was recruited. Type 1 diabetes mellitus was registered if fasting C-peptide was below 0.30 nmol L(-1). The E/I ratio was calculated as the mean of the longest R-R interval in expiration divided by the shortest in inspiration during deep breathing at 6 breaths min(-1) and taken to express the degree of CAN. A maximal symptom-limited exercise test was carried out and the VA Prognostic Score, indicating risk of cardiovascular death or non-fatal myocardial infarction, was computed. Additionally, the 10-year risk of CHD was calculated using the Framingham model. RESULTS: A total of 84 people responded, of whom 71 had Type 1 diabetes mellitus. The E/I ratio was measured in 69 people. The prevalence of CAN expressed as an E/I ratio below the normal 5th percentile was 38%. The E/I ratio was significantly reduced in old age, long duration of diabetes, female gender, high fasting blood glucose, triglyceride, systolic blood pressure and urinary albumin excretion. A high risk of future CHD calculated using the Framingham model was associated with a low E/I ratio (r = -0.39, P = 0.001). Exercise capacity, rise in systolic blood pressure and heart rate were positively correlated with the E/I ratio. A high VA Prognostic Score was correlated with a low E/I ratio (r = - 0.58, P < 0.0005). The risks estimated by the two models were significantly correlated (r = 0.60, P < 0.0005). CONCLUSION: The prevalence of CAN in the 40-75-year-old Type 1 diabetes mellitus population is estimated to be 38%. CAN is associated with exercise test parameters and a coronary risk factor profile indicating a high risk of future CHD.

Performance profile of the Starr-Edwards aortic cloth covered valve, track valve, and silastic ball valve.

OBJECTIVE: The Starr-Edwards aortic ball valve has passed 30 years of clinical follow-up. A detailed account of the long-term performance from a large series could thus give valuable guidance in managing patients who are still alive, depict the total remaining life-span after aortic valve replacement (AVR) for the average patient, and set a record yet to be matched by modern disc valves. METHODS: A detailed follow-up to a maximum of 31.1 years was performed for 717 patients who underwent their first AVR during 1965-1993 with a Starr-Edwards silastic ball valve (N = 355), a cloth covered valve (N = 164) or a track valve (N = 198) with a total of 7254 patient-years at risk. RESULTS: Patients who received a silastic ball valve were older (average 60 vs. 58 years), had more endocarditis (9%) and more secondary kidney failure (24%) preoperatively than the other patients. The three valve types did not differ as regards long-term survival or freedom from complications and only 15% of late deaths were related to the valve. For the silastic ball valve cumulative freedoms at 10 and 25 years were 59 and 20% from all deaths (crude survival), 85 and 80% from thromboembolism, 87 and 70% from bleeding, 98 and 94% from endocarditis, 96 and 95% from redo AVR and 68 and 51% from all valve related complications joined. There were no instances of structural failure apart from wear of the cloth covering the cage struts of the cloth covered valves. Incidences of haemolysis (0.10%/patient-year) and valve thrombosis (0.06%/patient-year) were low for the silastic ball valve. Analysis of relative survival for the silastic ball valve indicated excess mortality relative to a matched background population only during 1st and 13th postoperative year. Apart from heart related factors and age, independent incremental risk factors for mortality and the various complications included, not valve type, but valve size index (valve size divided by body surface area) < or = 13 mm/m2. CONCLUSIONS: The Starr-Edwards aortic ball valves, not least the currently available silastic ball valve, are durable through the remaining life time of the patients and able to secure near normal age and sex specific survival provided valve and patient size mismatch is avoided.

Parasympathetic function during deep breathing in the general population: relation to coronary risk factors and normal range.

OBJECTIVES: To examine the association between the parasympathetic function assessed by deep breathing-induced heart rate variability (HRV) and coronary risk factors and to establish a reference range for deep breathing-induced HRV. DESIGN: Cross-sectional population-based study. SETTING: The municipality of Horsens, Denmark. SUBJECTS: One hundred and ninety-four individuals aged 40-67 years without diabetes, atrial fibrillation or a pacemaker randomly selected from the population. MAIN OUTCOME MEASURES: During deep breathing at 6 respiratory cycles min-1, an ECG was taken and in three consecutive cycles the longest R-R interval during expiration (E) and the shortest during inspiration (I) were selected. The mean ratio (E/Iratio) and the mean difference in instantaneous heart rate (E/Idiff) were taken as expressions of the parasympathetic function. RESULTS: In multivariate analysis, E/Idiff was reduced with increasing age (P < 0.0005) and left ventricular mass (P = 0.008), with ECG sign of probable previous myocardial infarction (P = 0.020) and the use of cardiac medication (P = 0.018) and positively correlated to heart rate (P = 0.030). The E/Iratio was diminished with increasing age (P = 0.001), left ventricular mass (P = 0.003), waist-hip ratio (P = 0.044), with ECG sign of probable previous myocardial infarction (P = 0.012) and use of cardiac medication (P = 0.020), but no association was found with heart rate (P = 0.92). In both E/Idiff and E/Iratio, no correlation was found to lipids, blood pressure or alcohol consumption. In the group not on cardiac medication, without left ventricular hypertrophy or ECG sign of probable myocardial infarction, E/Idiff and E/Iratio were still independently correlated to age and left ventricular mass. In this group, equations defining the age-corrected 5th percentile were calculated. CONCLUSIONS: The parasympathetic function as assessed by deep breathing-induced HRV in the general population is reduced in older people, and in individuals on cardiac medication, with left ventricular hypertrophy or ECG signs of myocardial infarction. Even in healthy persons the parasympathetic function is inversely associated with age and left ventricular mass. Values of E/Idiff above (4.39-0.033 x age)2 and readings of E/Iratio above 1 + exp (-1.12-0.0198 x age) can be regarded as normal.

Increased QT dispersion in patients with insulin-dependent diabetes mellitus.

AIM: To compare the QT dispersion in unselected patients with insulin-dependent diabetes mellitus to non-diabetic control subjects and to assess the association between the QT dispersion and cardiac autonomic neuropathy, ischaemic heart disease, blood pressure level and nephropathy. METHODS: 42 patients with insulin-dependent diabetes mellitus and 80 control subjects aged 40-57 years participated. The QT interval was measured in a resting 12-lead electrocardiogram (ECG) and the QT dispersion defined as the difference between the maximum and minimum QT interval. Bazett's formula was used to correct for heart rate (QTc). The degree of cardiac autonomic neuropathy was assessed by five function tests and ischaemic heart disease was defined by a previous myocardial infarction, ECG abnormalities or a positive exercise test. RESULTS: Compared to control subjects, diabetic patients had a longer QTc interval (433 vs. 416 ms; P=0.002) and a higher QT dispersion (36 vs. 30 ms; P=0.02). In the diabetic group, the QTc interval was prolonged in patients with autonomic neuropathy (449 vs. 420 ms; P=0.007) and the QT dispersion was increased in patients with ischaemic heart disease (51 vs. 33 ms; P=0.004). No association was found to urinary albumin excretion rate or blood pressure. CONCLUSION: The QT dispersion as well as the QTc interval is increased in patients with insulin-dependent diabetes mellitus. The association between QT dispersion and ischaemic heart disease indicates that abnormalities in cardiac repolarisation may be caused by complications to diabetes rather than diabetes in itself.

The diurnal variation in blood pressure should be calculated from individually defined day and night times.

The aim of this study was to compare the nocturnal fall in BP parameters calculated from individually defined periods of day and night to values computed from collectively fixed day/night definitions. Day and night periods were defined according to 3 different methods: (i) the individually defined time of getting up and going to bed obtained from participant diaries (MethodIND); (ii) the mean time of rising and retiring in the group (MethodMEAN); and (iii) a daytime period from 07.00-22.00 h as recommended by The Scientific Committee (Method722). The ambulatory BP was recorded every 30 min over 24 h. One hundred and eighty-seven persons aged 40-66 years participated. With MethodIND, the BP load, systolic, diastolic and mean BPs were higher in the daytime and lower in the night-time compared to the results using Method722 and MethodMEAN. The nocturnal BP fall using MethodIND was larger than the fall calculated from every possible fixed division in the period from 3 h before till 3 h after the group mean time of getting up and going to bed (p < 0.001). The lowest frequency of non-dipping, defined as a nightly fall in systolic and diastolic BP below 10%, was observed using MethodIND (10%). Compared to MethodIND, 11% were misclassified as non-dippers by Method722 and 8% by MethodMEAN. We conclude that the diurnal blood pressure variation based on individually defined periods of day and night is larger than the variation based on any collectively fixed day/night definition. It is recommended that assessment of the nocturnal change in BP be based on individually defined periods of day and night.

Prevalence and prediction of silent ischaemia in diabetes mellitus: a population-based study.

OBJECTIVES: The aim of the study was to estimate the prevalence of silent ischaemia in diabetic subjects in the population, to compare the prevalence of silent ischaemia in diabetics and non-diabetics and to attempt to predict the presence of silent ischaemia in diabetic subjects. METHODS: A random sample of 120 users of insulin and 120 users of oral hypoglycaemic agents aged 40-75 years living in the Danish municipality of Horsens were asked to participate in the study. Corresponding to the youngest half of the sample two non-diabetic controls were randomly selected from the Central Population Register. ST-depression of horizontal or descending character of at least 0.1 mV measured 80 ms after the J-point on either exercise ECG or Holter ECG was considered indicative of myocardial ischaemia. Angina pectoris was considered present if the Rose questionnaire was positive, or chest pain was registered simultaneously with ECG evidence of ischaemia. Individuals with ischaemia, but without angina pectoris, were defined as persons with silent ischaemia. RESULTS: Seventy-four percent of the invited group were included. The observed prevalence of silent ischaemia in diabetics was 13.5% (95% CI = 8.5-19.8%). No association was found between silent ischaemia and gender (P = 0.83) or diabetes type (P = 0.67). In the group of diabetics who had controls, the prevalence was 11.4%, and among the controls the prevalence was 6.4% (OR = 1.87, one-sided P = 0.079). Systolic blood pressure was highly predictive of silent ischaemia in the diabetic subjects (P = 0.005). No predictive value could be shown for other variables. CONCLUSION: This is the first population-based study of silent ischaemia in diabetes. The prevalence of silent ischaemia in diabetic subjects was 13.5%. The frequency of silent ischaemia did not differ significantly between diabetics and non-diabetics. Systolic blood pressure was predictive of silent ischaemia in diabetes.