Transient ST segment depression during Holter monitoring: how to avoid false positive findings

An interactive model of pain and myocardial ischemia

The biopsychosocial model has been used to describe the intertwined factors that may act as mechanisms in cardiovascular disease, as well as those found in pain conditions. This model may also prove useful in understanding a diagnosis that overlaps these two areas, angina. This article reviews the literature related to biological, psychological, and social mechanisms of painful ischemic episodes and discusses the interactions of those variables. We propose an integrated model that incorporates the biopsychosocial mechanisms that may be responsible for the variability in pain reporting with ischemic episodes. We show how sex differences manifested in various biopsychosocial factors may interact to influence the presence of painful versus silent myocardial ischemia. We present a plan for future research to elucidate this interaction.

Vagal activity modulates spontaneous augmentation of ST elevation in the daily life of patients with Brugada syndrome

INTRODUCTION

In Brugada syndrome, ventricular fibrillation (VF) occurs mainly during sleep, and Brugada ECG signs are intensified by parasympathomimetic drugs; therefore, vagal activity could be a precipitating factor of VF. The aim of the present study was to elucidate the relation between spontaneous augmentation of ST elevation and changes in autonomic nervous activities in the daily life of patients with Brugada syndrome.

METHODS AND RESULTS

Twenty-three consecutive patients with Brugada syndrome were studied. Group VF(+) consisted of 7 symptomatic patients and 3 asymptomatic patients with inducible VF; group VF(-) consisted of 13 asymptomatic patients without documented or inducible VF. Two-channel unipolar lead (V(1) and V(2)) Holter ECG was recorded. Heart rate variability was analyzed by the maximum entropy method. Spontaneous augmentation of ST elevation (>/=1.5 mm/20 min) occurred more frequently during 24 hours in group VF(+) than in group VF(-) (5.7 +/- 2.5 times vs 2.3 +/- 2.4 times, P < 0.01). ST elevation was significantly greater in group VF(+) than in group VF(-) (2.1 +/- 0.2 mm vs 1.8 +/- 0.2 mm, P < 0.05). Power of the high-frequency component (HF: 0.15-0.4 Hz) and RR interval increased progressively, and the ratio of low-frequency component (LF; 0.04- 0.15 Hz) to high-frequency component (LF/HF) gradually decreased toward the time of maximum ST elevation. During an entire day, daytime (0-5 P.M.), and nighttime (0-5 A.M.), both HF and LF/HF were not different between groups VF(+) and VF(-).

CONCLUSION

In Brugada syndrome, spontaneous augmentation of ST elevation in daily life occurred along with an increase in vagal activity. ST elevation was augmented more in patients with VF than in those without VF under similar vagal tone.

ST segment analysis by Holter Monitoring: methodological considerations

BACKGROUND

There has been a renewed interest in ST segment analysis by Holter Monitoring, especially in multicenter clinical trials, but consensus on how to define an ischemic event is missing. We conducted a survey of European and U.S. publications involving ST segment analysis by Holter monitoring from 1975 to 2002 and found no notation of any correction for baseline ST segment depression in 52% of them. In 45% J-point depression was required in addition to ST segment depression measured either 60 ms (24%) or 80 ms (76%) after the J point. In 28% ST segment elevations were included.

METHOD

Four different criteria for an ischemic event found in our survey were applied to Holter recordings from 66 patients with acute ischemic syndrome enrolled in the Esmolol Myocardial Ischemia Trial (EMIT). Only lead CM5 was used and the analyzer was a Reynolds Medical Pathfinder 600.

RESULTS

By the most sensitive method (J + 80), there were 16 (24%) patients who had ischemic events in their Holter recording compared to only 10 (15%) patients if J-point depression was also required. If corrections were made for baseline ST segment depression, only 3 (4.5%) recordings were positive for ischemia.

CONCLUSION

The outcome of Holter analysis for ischemic events is greatly dependent upon how an ischemic event is defined. Consensus on how to define an ischemic event is urgently needed.

Three-year follow-up of patients with silent ischemia in the subacute phase of myocardial infarction after thrombolysis and early coronary intervention

In order to assess the prognostic value of silent myocardial ischemia in acute myocardial infarction after thrombolysis and early coronary angiography (14-48 h after start of thrombolysis) including percutaneous transluminal coronary angioplasty, if indicated, 126 patients underwent 24 h-Holter-monitoring in the early postinfarction period. The 24 h-Holter-recording was initiated directly after early coronary intervention (40+/-11 h after onset of symptoms). Of the 126 patients initially eligible for the study 29 had to be excluded from further analysis for clinical or methodical reasons. Of the remaining 97 patients, 10 (10%) had silent ischemia (group A) and 87/97 (90%) patients showed no significant ST-segment alterations. Both groups did not significantly differ from each other with regard to baseline clinical characteristics, severity of coronary artery disease and frequency of successful percutaneous transluminal coronary angioplasty. The left ventricular ejection fraction showed a trend towards lower values in patients with than in those without silent ischemia (47+/-15% vs. 55+/-13%, p=0.07). When both silent ischemia and left ventricular ejection fraction <40% were present, a subset of patients at high risk for cardiac death could be identified (specificity: 98%, positive predictive accuracy: 75%). By Kaplan-Meier analysis, significantly more cardiac deaths occurred in group A than in group B (30% vs. 6%, p<0.01) during the three-year follow-up (950+/-392 days) after acute myocardial infarction. Regarding the cardiac events during long-term follow-up (emergency percutaneous transluminal coronary angioplasty, coronary artery bypass grafting, non-fatal reinfarction, and cardiac death) there was no significant difference between both groups (30% vs. 18%, NS). In conclusion, Holter monitor-detected silent ischemia in the subacute phase of myocardial infarction after thrombolysis followed by early delayed coronary intervention occurs in 10% of the patients indicating either a residual ischemia in the infarcted zone despite a combined reperfusion strategy or a remote ischemic potential in case of multivessel disease. In this small selected group of infarct patients too, silent ischemia is to be considered as an important non-invasive parameter to predict cardiac death during long-term follow-up and provides valuable complementary information to left ventricular dysfunction, a well established prognostic marker in the postinfarction period.

ST-segment deviation during 24-hour ambulatory electrocardiographic monitoring and exercise stress test in healthy male subjects 51 to 75 years of age: the Copenhagen City Heart Study

BACKGROUND

Although ST-segment deviation has been evaluated and used during many years both on continuous electrocardiographic Holter monitoring and during exercise stress testing, considerable controversy still remains concerning the prevalence and diagnostic significance of fortuitously discovered ST-segment deviation in asymptomatic healthy persons.

METHODS AND RESULTS

The occurrence of ST-segment deviation was studied in a population of 63 clinically healthy male subjects 51 to 75 years of age, with the use of 24-hour Holter monitoring and exercise stress testing. The subjects were recruited from the Copenhagen City Heart Study and were without cardiovascular risk factors, chronic diseases, or medication and without cardiovascular events during 5 to 12 years before and 3 to 5 years after admission. The specificity, that is, the probability of displaying a negative test result in healthy subjects without disease, was 1.0 when using as criterion for significant ST-segment deviation a horizontal or descending ST-segment depression of >0.20 mV or ST-segment elevation >/=0.15 mV during Holter monitoring, and acceptable, for example, 0.95, when using as criterion a horizontal or descending ST-segment depression of >/=0.15 mV during Holter monitoring or at the exercise test, respectively. Furthermore, the specificity was 0.95 when a horizontal or downsloping ST-segment depression of 0.1 mV was displayed in both the Holter and exercise electrocardiographic recording system.

CONCLUSIONS

Thus in asymptomatic persons, the usual criterion for significant ST-segment depression of 0.1 mV can be applied when occurring in both electrocardiographic recording systems. However, if one test alone is used, the criterion of significant ST-segment depression should be 0.15 mV. Absence of ST-segment deviation during Holter monitoring and exercise stress testing, indicated with a specificity of 1.0 or 0.95 according to choice of criterion, implies that the person is in a healthy state.

Prognostic value of ischemia during Holter monitoring and exercise testing after acute myocardial infarction

Exercise testing is generally accepted for prognostic assessment of patients after infarction, but the prognostic value of transient myocardial ischemia during ambulatory electrocardiographic monitoring remains controversial. Of 281 consecutive postinfarction patients, 173 patients (132 men, 41 women) were prospectively studied with 24-hour Holter monitoring 14 +/- 5 days after acute myocardial infarction, and with submaximal exercise testing after 15 +/- 7 days. Patients with either conduction disturbances or pacemaker rhythm and 71 patients with digitalis medication were excluded. Myocardial ischemia was defined as horizontal or descending ST depressions or transient ST elevations > or = 0.1 mV with or without angina pectoris. The follow-up period was 1 year. Myocardial ischemia was observed in 40 patients (23%) during Holter monitoring, and 96% of the episodes were asymptomatic. Ischemia occurred during exercise testing in 46 patients (27%), two thirds of whom had no symptoms. Ischemia was detected by both methods (group A) in 19 patients (11%), with exercise testing only (group B) in 27 patients (16%), and with Holter monitoring only (group C) in 21 patients (12%). In 106 patients (61%), ischemia could not be ascertained at all. The 4 groups were comparable with regard to sex and age distribution, coronary risk factors, and medication. During follow-up, 50 patients (29%) experienced clinical cardiac events: 6 patients died, 7 had recurrent myocardial infarction, 14 developed unstable angina pectoris and required immediate revascularization, and 23 patients had recurrent but stable angina.(ABSTRACT TRUNCATED AT 250 WORDS)