Interrelations Between Hypertension and Electrocardiographic Left Ventricular Hypertrophy and Their Associations With Cardiovascular Mortality.

Electrocardiogram (ECG) is the most common method for assessment of left ventricular hypertrophy (LVH) in contemporary clinical trials. However, our understanding of the relation between hypertension and LVH is based on studies used imaging to ascertain LVH. To fill this gap in knowledge, we examined the interrelationships between hypertension, ECG-LVH and cardiovascular disease (CVD) mortality in 6,105 patients free of CVD who were followed for 14.0 years (median). The was an exponentianl ECG-LVH prevalence rates (2.40%, 4.45%, 5.75%, 8.51%, 14.38%) were exponentially increases as systolic blood pressure increases (<120 mm Hg, 120 to 129 mm Hg, 130 to 139 mm Hg, 140 to 159 mm Hg, >160 mm Hg, respectively); trend p value <0.001. Hypertension was associated with more than double the risk of ECG-LVH (odds ratio (95% confidence interval [CI]) 2.45 [1.83, 3.30]), and each standard-deviation increase in systolic blood pressure (19 mm Hg) was associated with 49% increased odds of ECG-LVH (odds ratio [95% CI] 1.49 [1.38, 1.61]). During follow-up, 733 CVD-deaths occurred. In separate Cox models, both ECG-LVH and hypertension were associated with CVD mortality (hazard ratio [95% CI] 1.39 [1.07, 1.81] and 1.39 [1.18, 1.62], respectively). However, when ECG-LVH and hypertension were entered together in the same model, the risk of CVD mortality was essentially unchanged for hypertension after adjusting for ECG-LVH, but markedly attenuated for ECG-LVH after adjusting for hypertension. In conclusion, the relation between hypertension and ECG-LVH follows a similar pattern to that reported in literature for imaging-LVH which provides support for the current practice of using ECG for assessment of LVH in contemporary hypertension clinical trials. The inability of ECG-LVH to explain the association between hypertension and CVD mortality suggests that LVH is only one of many factors by which hypertension exerts its impact on CVD.

Peguero Electrocardiographic Left Ventricular Hypertrophy Criteria and Risk of Mortality.

Background: Peguero electrocardiographic left ventricular hypertrophy (ECG-LVH) criteria are newly developed criteria that have shown better diagnostic performance than the traditional Cornell-voltage and Sokolow-Lyon criteria. However, prediction of poor outcomes rather than detection of increased left ventricular mass is becoming the primary use for ECG-LVH criteria which requires investigating any new ECG-LVH criteria in terms of prediction. Aims: To examine the prognostic significance of the newly developed Peguero ECG-LVH criteria. Methods: We compared the prognostic significance of Peguero ECG-LVH with Cornell-voltage and Sokolow-Lyon ECG-LVH criteria in 7,825 participants (age 59.8 ± 13.4 years; 52.7% women) from the third National Health and Nutrition Examination Survey who were free of major intraventricular conduction defects. ECG-LVH criteria were derived from digital ECG tracings processed at a central core laboratory. Results: At baseline, ECG-LVH was detected in 11.8% by Peguero; in 4.3% by Cornell voltage and in 6.4% by Sokolow-Lyon. During a median follow up of 13.8 years, 2,796 all-cause mortality events occurred. In multivariable models adjusted for demographics and cardiovascular risk factors, presence of Peguero ECG-LVH was associated with increased risk of all-cause mortality [HR (95% CI): 1.29 (1.16, 1.44)]. This association was not significantly different from the associations of Cornell voltage-LVH or Sokolow-Lyon LVH with all-cause mortality [HR (95%CI): 1.32 (1.12, 1.55) and 1.24 (1.07, 1.43), respectively; p-values for comparisons of these HRs with the HR of Peguero ECG-LVH 0.817 and 0.667, respectively]. Similar patterns of associations were observed with cardiovascular, ischemic heart disease and heart failure mortalities. Conclusion: Peguero ECG-LVH is predictive of increased risk of death similar to the traditional ECG-LVH criteria.

Racial Differences in Heart Age and Impact on Mortality.

BACKGROUND: Heart age is an estimate of the age of a person's cardiovascular system given their cardiovascular disease (CVD) risk factors. The difference between a person's chronological age and heart age (excess heart age) represents their added CVD risk. OBJECTIVE: To examine racial differences in excess heart age and whether race impacts the association between excess heart age and CVD mortality. METHODS: This analysis included 5110 participants (2449 non-Hispanic white, 1287 non-Hispanic black, and 1374 Mexican-American) from the NHANES III who were free of CVD. Heart age was calculated using the sex-specific non-laboratory-based Framingham risk prediction functions. Multivariable Cox proportional-hazards regression models were used to evaluate the relationship (overall and by race) between excess heart age and CVD mortality. RESULTS: Mean excess heart age was greatest in non-Hispanic blacks (13.0 years), followed by Mexican-Americans (10.5 years), and non-Hispanic whites (8.5 years); p < 0.001 for pairwise differences. Over a mean follow-up of 13.0 years, 394 CVD deaths occurred. Each 10 years of excess heart age was associated with 65% increased risk of CVD mortality (HR, 95% CI: 1.65, 1.53-1.78). This association was stronger in non-Hispanic whites (1.83, 1.63-2.02) compared to non-Hispanic blacks (1.50, 1.29-1.72) and Mexican American (1.60, 1.33-1.87), interaction p = 0.065. CONCLUSIONS: Compared to non-Hispanic whites, non-Hispanic blacks and Mexican Americans have more excess heart age, but the risk of CVD death for the same level of excess heart age appears more pronounced in non-Hispanic whites. Further investigation is needed to show the usefulness of these findings in directing future efforts and resource allocation for reduction of health disparities between ethnic groups.

Association between low diastolic blood pressure and subclinical myocardial injury.

BACKGROUND: Coronary arteries perfuse cardiac myocytes during diastole. We hypothesized that marked lowering of diastolic blood pressure (DBP) is associated with increased risk of subclinical myocardial injury (SC-MI). METHODS: This analysis included 6107 participants without history of cardiovascular disease (CVD) from the third National Health and Nutrition Examination Survey. SC-MI was determined by a validated electrocardiogram-based scoring system. Logistic regression was used to examine the cross-sectional association between DBP (< 70, 70-80 mmHg (reference group), and > 80 mmHg; and per each 10 mmHg decrease, separately) with SC-MI across levels of systolic blood pressure (SBP) (< 120, 120-139, or > 140 mmHg). RESULTS: In a multivariable model, DBP < 70 mmHg was associated with a higher risk of SC-MI [OR (95% CI) 1.40 (1.02, 1.94)] in participants with SBP > 140 mmHg. This association was consistent in subgroups stratified by age, race, diabetes, hypertension, obesity and smoking, but was stronger in women than in men [OR (95% CI) 1.58 (1.06, 2.37) vs. 1.10 (0.62, 1.94), respectively; interaction p value = 0.006]. Also, among participants with SBP > 140 mmHg, every 10 mmHg decrease in DBP was associated with a 12% increased odds of SC-MI [OR (95% CI) 1.12 (1.01, 1.23)]. No significant associations between DBP and SC-MI were observed in those with SBP < 120 mmHg or 120-139 mmHg, or between DBP > 80 mmHg and SC-MI in any of SBP levels. CONCLUSIONS: Low DBP < 70 mmHg in those with SBP > 140 mmHg carries higher risk of SC-MI, especially in women. Further research is needed to understand the therapeutic implications of these findings.

Digitizing paper electrocardiograms: Status and challenges.

The paper electrocardiogram (ECG) has been widely used for cardiac assessment for well over a century. ECGs can be obtained quickly and cheaply. For this reason, an ever-growing amount of paper ECG records continue to accumulate, some of which are stored into a paper-only format. Converting paper ECGs into digital form has been proposed as the most efficient means to store and analyze an otherwise cumbersome paper archive. In this article, a literature review was conducted for conversion algorithms, criticisms of said algorithms, applications, and standardization efforts. The algorithms were compared in tabulated form. Key functions that have advanced the conversion algorithms as well as remaining challenges are discussed.