Association of isolated minor nonspecific ST-T abnormalities with left ventricular hypertrophy and diastolic dysfunction

Nonspecific ventricular repolarization abnormalities: A wolf in sheep's clothing

The term nonspecific ventricular repolarization abnormalities refers to a set of minor alterations of the ST segment and/or the T wave. For a long time, they have been of little clinical interest as they do not translate into specific diagnoses. It has even been asserted that they constitute benign electrocardiographic findings. Their presence has been reported in various cardiovascular and non-cardiovascular diseases. However, it is frequently identified in apparently healthy asymptomatic people. A growing number of studies demonstrate their importance as predictors of cardiovascular morbidity and mortality, expanding their spectrum towards cardiovascular prevention. In light of the body of scientific evidence, it is imperative that the traditional view of nonspecific ventricular repolarization abnormalities changes.

Prognostic significance of flat T-waves in the lateral leads in general population

BACKGROUND

Negative T-waves are associated with sudden cardiac death (SCD) risk in the general population. Whether flat T-waves also predict SCD is not known. The aim of the study was to examine the clinical characteristics and risk of SCD in general population subjects with flat T-waves.

METHODS

We examined the electrocardiograms of 6750 Finnish general population adults aged ≥30 years and classified the subjects into 3 groups: 1) negative T-waves with an amplitude ≥0.1 mV in ≥2 of the leads I, II, aVL, V4-V6, 2) negative or positive low amplitude T-waves with an amplitude <0.1 mV and the ratio of T-wave and R-wave <10% in ≥2 of the leads I, II, aVL, V4-V6, and 3) normal positive T-waves (not meeting the aforesaid criteria). The association between T-wave classification and SCD was assessed during a 10-year follow-up.

RESULTS

A total of 215 (3.2%) subjects had negative T-waves, 856 (12.7%) flat T-waves, and 5679 (84.1%) normal T-waves. Flat T-wave subjects were older and had more often cardiovascular morbidities compared to normal T-wave subjects, while negative T-wave subjects were the oldest and had most often cardiovascular morbidities. After adjusting for multiple factors, both flat T-waves (hazard ratio [HR] 1.81; 95% confidence interval [CI] 1.13-2.91) and negative T-waves (HR 3.27; 95% CI 1.85-5.78) associated with SCD.

CONCLUSIONS

Cardiovascular risk factors and disease are common among subjects with flat T-waves, but these minor T-wave abnormalities are also independently associated with increased SCD risk.

Electrocardiographic ST-T Abnormities Are Associated With Stroke Risk in the REGARDS Study

Background and Purpose- In previous studies, isolated nonspecific ST-segment and T-wave abnormalities (NSSTTAs), a common finding on ECGs, were associated with greater risk for incident coronary artery disease. Their association with incident stroke remains unclear. Methods- The REGARDS (Reasons for Geographic and Racial Differences in Stroke) study is a population-based, longitudinal study of 30 239 white and black adults enrolled from 2003 to 2007 in the United States. NSSTTAs were defined from baseline ECG using the standards of Minnesota ECG Classification (Minnesota codes 4-3, 4-4, 5-3, or 5-4). Participants with prior stroke, coronary heart disease, and major and minor ECG abnormalities other than NSSTTAs were excluded from analysis. Multivariable Cox proportional hazards regression was used to examine calculate hazard ratios of incident ischemic stroke by presence of baseline NSSTTAs. Results- Among 14 077 participants, 3111 (22.1%) had NSSTTAs at baseline. With a median of 9.6 years follow-up, 106 (3.4%) with NSSTTAs had ischemic stroke compared with 258 (2.4%) without NSSTTAs. The age-adjusted incidence rates (per 1000 person-years) of stroke were 2.93 in those with NSSTTAs and 2.19 in those without them. Adjusting for baseline age, sex, race, geographic location, and education level, isolated NSSTTAs were associated with a 32% higher risk of ischemic stroke (hazard ratio, 1.32 [95% CI, 1.05-1.67]). With additional adjustment for stroke risk factors, the risk of stroke was increased 27% (hazard ratio, 1.27 [95% CI, 1.00-1.62]) and did not differ by age, race, or sex. Conclusions- Presence of NSSTTAs in persons with an otherwise normal ECG was associated with a 27% increased risk of future ischemic stroke.

Relation of Minor Electrocardiographic Abnormalities to Cardiovascular Mortality

Although minor electrocardiographic (ECG) abnormalities are common findings in clinical practice, their prognostic significance remains unclear due to inconsistent reports. We hypothesized that this inconsistency is due to the traditional focus on examining their prognostic significance as a binary variable (i.e., presence vs absence of any abnormality) ignoring the number of abnormalities. We tested this hypothesis in 6,467 participants (mean age 59 years, 53% women) from the Third National Health and Nutrition Examination Survey who were free of baseline cardiovascular disease (CVD) and major ECG abnormalities. ECG abnormalities were defined from digitally recorded and centrally processed standard electrocardiograms using the Minnesota ECG Classification. CVD mortality was ascertained using National Death Index. About 38% of participants (n = 2,438) had at least 1 minor ECG abnormality at baseline. During a median follow-up of 13.9 years, 755 CVD deaths occurred. In a multivariable Cox model, presence of at least 1 minor ECG abnormality was marginally associated with increased risk of CVD mortality (hazard ratio (95% confidence interval):1.15(1.00,1.34), p-value = 0.04)). However, as the number of ECG abnormalities increases, the association with CVD mortality showed a dose-response relation (event rate per 1,000 person-year of 7.3, 10.1, and 16.7 in participants with 0, 1, and ≥2 ECG abnormalities, respectively; p-value for trend <0.01). Also, each additional minor ECG abnormality was associated with a 13% increased risk of CVD mortality (hazard ratio (95% confidence interval): 1.13(1.04, 1.24)). In conclusion, the number, not only the mere presence of minor ECG abnormalities should be taken into account to understand the prognostic significance of these common findings.