Electrocardiographic reference values for a population of older adults in sub-Saharan Africa.

BACKGROUND/OBJECTIVES: Older adults in sub-Saharan Africa (SSA) are at greatest risk of an impending noncommunicable diseases epidemic, of which cardiac disease is the most prevalent contributor. Thus, it is essential to establish electrocardiographic reference values for a population that is likely to differ genetically and environmentally from others where reference values are established. METHODS: Two thousand two hundred thirty-two apparently healthy community-based participants without known cardiac disease aged 70+ in rural Tanzania underwent 12-lead electrocardiography. Electrocardiograms were digitally analyzed and gender-specific reference values for P duration (PD), P amplitude (PAMP), P area (PAREA), P terminal negative force (V1) (PTNF), PR interval, QRS duration (QRSD), QT/QTc, R amplitude (II, V5) (RAMP) LVH index (LVHI), R axis and R/S ratio (V1) reported, following univariate analysis of covariance using a multiple linear regression model, adjusting for age, systolic blood pressure (SBP), body mass index (BMI), and RR interval. RESULTS: Data from 1824 subjects were suitable for analysis. Adjusted mean values for men/women were: PD 115/110 ms, PAMP (avg) 123/114 µV, PAMP (II) 203/190 µV, PAREA (avg) 5.3/4.6 mV*s, PAREA (II) 9.3/8.1 mV*s, PTNF 1.7/1.4 mV*s, PR 158/152 ms, QRSD 89/84 ms, QT 370/375 ms, QTc 421/427 ms, RAMP (II) 805/854 µV, (V5) 2022/1742 µV, LVHI 3.0/2.8 mV (Sokolow-Lyon), 1.293/1.146 mV (Cornell), R axis 51/49°, R/S 0.2/0.2. Excluding PTNF , R axis and R/S ratio, all gender differences were significant (P < 0.001 apart from LVHI [Sokolow-Lyon; P < 0.005)] and RAMP (II) [P < 0.05]) following adjustment for age, SBP, BMI, and RR interval. CONCLUSIONS: Our description of comprehensive electrocardiographic parameters establishes reference values in this genetically and environmentally diverse SSA population thereby allowing identification of "outliers" with potential cardiac disease.

Electrocardiographic assessment of coronary artery disease and stroke risk factors in rural and urban Tanzania: a case-control study.

BACKGROUND: Although the association between cerebrovascular and coronary artery disease (CAD) is well known in high-income countries, this association is not well documented in black Africans. AIMS: The aim of this study was to document electrocardiographic (ECG) evidence of CAD in stroke cases and controls and to identify other common ECG abnormalities related to known stroke risk factors in a community-based population of incident stroke cases in Tanzania, East Africa. METHODS: This was a case-control study. Incident stroke cases were identified by the Tanzanian Stroke Incidence Project. Age- and sex-matched controls were randomly selected from the background population. Electrocardiograms were manually analyzed using the Minnesota Coding System, looking for evidence of previous myocardial infarction (MI), atrial fibrillation (AF) or atrial flutter (AFl), and left ventricular hypertrophy (LVH). RESULTS: In Hai, there were 93 cases and 241 controls with codable electrocardiograms, and in Dar-es-Salaam, there were 39 cases and 72 controls with codable electrocardiograms. Comparing cases and controls, there was a higher prevalence of MI and AF or AFl (but not LVH) in cases compared with controls. CONCLUSIONS: This is the first published study of ECG assessment of CAD and other stroke risk factors in an incident population of stroke cases in sub-Saharan Africa. It suggests that concomitant CAD in black African stroke cases is more common than previously suggested.

Effect of sex, age, and weight on ejection fraction and end-systolic volume reference limits in gated myocardial perfusion SPECT.

BACKGROUND: The left-ventricular ejection fraction (EF) and end-systolic volume (ESV) are strong predictors of prognosis for cardiac death. Gated myocardial perfusion single-photon emission computed tomography (gSPECT) may be used to measure ESV and EF. However, systematic differences may exist between referred populations. Our aim was to derive male and female reference limits for left-ventricular functional parameters, and determine the effect of age, weight, and body surface area (BSA). METHODS AND RESULTS: The ejection fraction and ESV were derived using QGS software for 127 patients with normal gSPECT studies. The lower reference limits of EF were 46.2% and 55.6% for men and women, respectively. The upper reference limits of ESV were 30.4 mL and 21.4 mL, and 15.7 mL/m(2) and 11.1 mL/m(2), when indexed to BSA for men and women, respectively. There was no correlation between EF and age, weight, or BSA (P > .05). There was a small decrease in ESV with age, and an increase with weight and BSA (P < .05). The sex-specific differences remained after adjusting for confounding variables. CONCLUSIONS: We demonstrated a significant sex difference for all functional parameters measured, and we established the influence of patient age and weight. Local reference limits for ESV and EF have been established, and the latter are transferable to other departments operating similar protocols.

Strikingly low prevalence of atrial fibrillation in elderly Tanzanians.

OBJECTIVES: To determine the prevalence of atrial fibrillation (AF) in individuals aged 70 and older in a rural African community. DESIGN: Community-based cross-sectional survey. SETTING: A demographic surveillance site (DSS) within the rural Hai district of northern Tanzania. PARTICIPANTS: Approximately one-quarter (N = 2,232) of the population aged 70 and older of the DSS. MEASUREMENTS: Participants were screened for AF using 12-lead electrocardiography; demographic and 1-year mortality data were collected; and functional status, body mass index, and blood pressure were recorded. The sex-specific prevalence of AF in each 5-year age band was determined. RESULTS: Fifteen of 2,232 participants (12 women, 3 men) had AF, giving a crude prevalence rate of 0.67% (95% confidence interval (CI) = 0.33-1.01) and an age-adjusted prevalence of 0.64% (95% CI = 0.31-0.97). Prevalence was 0.96% (95% CI = 0.42-1.49) in women and 0.31% (95% CI = -0.04 to 1.24) in men. Prevalence increased with age, from 0.46% (95% CI = 0.01-0.90) in those aged 70-74-1.30% (95% CI = 0.17-2.42) in those aged 85 and older. One-year mortality was 50% in women and 66.6% in men. CONCLUSIONS: This is the first published community-based AF prevalence study from sub-Saharan Africa. The prevalence rate of AF is strikingly lower than in other elderly populations studied, yet the 1-year mortality rate was exceedingly high.

Acquired supravalvular aortic stenosis: a late complication of replacement of the ascending aorta.

Aortic syndromes are an increasing cause of morbidity and mortality. Ascending aortic dissection is a clinical emergency with most patients requiring open surgery to replace the ascending aorta. Detection through clinical suspicion, improved non-invasive imaging and refined surgical techniques have resulted in an improved survival rate. Acquired supravalvular aortic stenosis is an extremely rare complication of cardiac surgery. We present the case of a patient who, 15 years after undergoing elective replacement of the ascending aorta for aortic dissection, required repeat surgery for symptomatic supravalvular aortic stenosis. This case elegantly highlights the need for a detailed focused assessment in patients where the clinical presentation does not correlate with initial investigations. To our knowledge this is the first reported case of late symptomatic supravalvular aortic stenosis following replacement of the ascending aorta.