Electrocardiograms in hypertensive subjects from a population random sample: basic characteristics and correlations with some biological variables
Zamboni, S.; Ambrosio, G.B.; Bertoldero, G.; Bugaro, L.; Dal Palù, C.
Giornale Italiano di Cardiologia 15(4): 375-382
1985
ISSN/ISBN: 0046-5968 PMID: 2931318 Document Number: 254854
During the initial phase of the WHO Community Control Programme of Hypertension in Italy, 1190 hypertensives (of both sexes, aged 20-64) were identified through the screnning of 5856 people randomly selected from the whole population of the community of Camposampiero (Padova), and had a standard ECG tracing recorded. ECGs were all read according to the 2nd version of the Minnesota code (MC), by only one coder. First of all, the prevalence of the various items of MC in the two sexes was calculated. Absolutely normal ECGs (item 1-0) were found in 41.1% of the examined subjects; another 23.3% had only a shift of the transition zone to the right or the left (items 9-4). Among pathological codes, the most frequent were those of class 3 relating to left ventricular hypertrophy (LVH) (i.e. 3:1 or 3:3) and those of classes 4, 5 and 7 relating to myocaridal ischaemia (ISC) (i.e. 4:1-3 or 5:1-3 or 7-1). The overall frequencies of LVH and, respectively, of ISC (calculated by suitable grouping the above described items) were as follows. LVH: 21.3% in males (M), 14.6% in females (F); ISC: 5.7% in M, 18.1% in F. A significant (p < 0.005) positive correlation with age was found both for LVH and ISC codes in F, only for ISC codes in M. A significant negative correlation between LVH codes and body mass index (BMI) was instead evident only in males. The increasing prevalence of both LVH and ISC codes in F and just of ISC codes in M, with increasing SBP, is in agreement with the well recognized role of SBP as a determinant of both myocardial hypertrophy and coronary heart disease. The lack of a significant correlation between LVH codes and age in males mainly depends on the fact that the highest prevalence of LVH codes is found just in the lowest class of age. This finding might be explained by the influence of some constitutional characteristics of young males (e.g. thin chest wall) which, in relation to the voltage criteria of the MC, could give rise to many false positive LVH patterns in this age group. The reduction of R wave amplitude particularly on the precordial leads-reported in overweight or frankly obese subjects could in turn explain the negative correlation between the prevalence of LVH codes and BMI values in males.