Analysis of ST segment depression in supraventricular tachycardia and its relationship with underlying mechanism.

BACKGROUND: Electrocardiographic diagnosis of causes of supraventricular tachycardia (SVT) is sometimes difficult and application of routine algorithms can lead to misdiagnosis in as many as 37 % of patients. ST segment depression may be useful in diagnosing the nature of SVT. METHODS: We reviewed surface electrocardiogram (ECG) characteristics of 300 patients having SVT with 1:1 AV relationship and correlated findings with electrophysiology study (EPS) findings. Final diagnosis of AVNRT (Atrioventricular nodal reentrant tachycardia), Orthodromic AVRT (atrioventricular reentrant tachycardia) and atrial tachycardia (AT) was correlated with ECG parameters like heart rate, ST segment depressions and QRS morphology. RESULTS: Out of 300 patients, majority patients included in study, were having AVNRT or AVRT. ST depression predicted AVRT if the ST depression was ≥ 2 mm (overall sensitivity of 38.3 % and specificity of 93.8 % to predict AVRT) and was downsloping in morphology (sensitivity of 36.9 % and specificity of 94.7 % to predict AVRT). At heart rates ≥214 beats per minute (bpm) as measured by 7 small squares of ECG at 25 mm/s, downsloping ST depression ≥2 mm had a sensitivity 37.9 % of and specificity of 89.2 % to predict AVRT. At heart rate <214 bpm, downsloping ST depression ≥2 mm had sensitivity of 37.2 % and specificity of 96.5 % to predict AVRT. Downsloping ST depression of ≥2 mm helps to differentiate AVNRT from AVRT. CONCLUSION: A downsloping ST segment depression ≥2 mm predicted SVT being an AVRT and can be used as a useful criteria in diagnosing the tachycardia.

Arterial Stiffness is Associated with False-Positive ST-Segment Depression in Supine Bicycle Exercise Stress Echocardiography.

Background: Although exercise stress electrocardiography (ECG) is a popular tool for detecting coronary artery disease (CAD), the induced ST-depression without coronary artery stenosis (FST) remains a challenge for accurate diagnosis. Exercise-induced ST depression is related to poor prognosis even in non-obstructive disease; however, its determinants have not been fully defined. We sought to investigate whether ventriculo-vascular interactional indexes such as arterial stiffness index, exercise hemodynamic parameters and echocardiographic left ventricular (LV) functional parameters were related to FST. Methods: In the current study, 609 participants who underwent both supine bicycle exercise echocardiography and brachial-ankle pulse wave velocity (baPWV) measurement without exercise-induced regional wall motion abnormalities (RWMA) were analyzed. Referral reasons for stress test were CAD detection or evaluation of patency of previous revascularization. Stepwise graded supine bicycle exercise was performed with simultaneous ECG recording and echocardiography after full conventional resting echocardiography. The FST was defined as newly developed > 1 mm ST depression without RWMA during exercise. Results: The median age of the study participants was 65 (59.0-70.5) years, and 222 (37%) patients were women. Among them, 103 (17%) patients showed FST during the exercise or recovery phase. The prevalence of FST did not differ between sexes. Older age, higher pulmonary arterial systolic pressure (PASP), left atrial volume index, baPWV and ankle brachial index at rest and hypertensive response, higher heart rate and rate-pressure product at peak exercise were significantly associated with FST. In multivariate analysis, higher peak heart rate, PASP, and baPWV were independently related to FST. Conclusions: Stress-induced RWMA in addition to ECG should be evaluated to detect CAD in patients with higher baPWV and PASP. FST might be linked to subclinical myocardial ischemia through arterial stiffness and diastolic dysfunction.

A large population-based study on the prevalence of electrocardiographic abnormalities: A result of Mashhad stroke and heart atherosclerotic disorder cohort study.

BACKGROUND: Twelve-lead electrocardiogram (ECG) is a common and inexpensive tool for the diagnostic workup of patients with suspected cardiovascular disease, both in clinical and epidemiological settings. The present study was designed to evaluate ECG abnormalities in Mashhad population. METHODS: ECGs were taken as part of MASHAD cohort study (phase1) and were coded according to the Minnesota coding criteria. Data were analyzed using SPSS. RESULTS: Total 9035 ECGs were available for final analysis including 3615 (40.0%) male and 5420 (60.0%) female. Among ECG abnormalities precordial Q wave, major T-wave abnormalities, inferior Q wave, sinus bradycardia, and left axis deviation were the most prevalent abnormalities. The frequency of precordial and inferior Q wave, inferior QS pattern, major and minor ST abnormalities, major and minor T abnormalities, Wolff-Parkinson-White and Brugada pattern, sinus bradycardia, sinus tachycardia, left axis deviation, ST elevation, and tall T wave were significantly different between two genders. Moreover, the frequency of Q wave in precordial and aVL leads, QS pattern in precordial and inferior leads, major and minor T-wave abnormalities, Wolff-Parkinson-White, atrial fibrillation, sinus bradycardia, left axis deviation, and ST elevation were significantly different in different age groups. A comparison of the heart rate, P-wave duration, and QRS duration between men and women indicated that there was a significant difference. CONCLUSIONS: Our finding indicated that the prevalence ECG abnormalities are different between men and women and also it varied in different age groups.

The de Winter ECG pattern: Distribution and morphology of ST depression.

BACKGROUND: The reported positive predictive value (PPV) for the "de Winter ECG pattern" to predict an acute left anterior descending artery (LAD) lesion is inconsistent. Besides, the morphology of upsloping or nonupsloping ST depression (STD) may have different significance of severity and prognostication. METHODS: We searched the MEDLINE database using "de Winter" or "junctional ST-depression with tall symmetrical T-waves" or "tall T wave" or "STEMI equivalent" as the item up to March 2020. We compared the ECG differences between the different culprit arteries and various morphological STD. RESULTS: A total of 70 patients with analyzable ECGs were included. In 60 patients (LAD group), the LAD was the culprit artery, while in 10 patients (non-LAD group), there were other etiologies. Maximal STD in V2 or V3 had a PPV of 89% of all patients and 98% of patients without ST elevation in V2 to detect an acute LAD lesion. The presence of q/Q-wave or poor R-wave progression in the precordial leads was significantly more often found in patients with upsloping STD than in patients with nonupsloping STD in the LAD group (84% vs. 27%, p < .01). In 18 patients, the ECG showed a change from upsloping to nonupsloping STD from the leads with maximal STD to the surrounding leads with less STD. CONCLUSIONS: The location of the maximal STD in the precordial leads differs between patients with LAD as the culprit artery and other etiologies of the de Winter ECG pattern. Upsloping STD signifies more severe signs of ischemia than nonupsloping STD.

Relation of collateral circulation with reciprocal changes in patients with acute ST-elevation myocardial infarction.

OBJECTIVE: Acute STEMI is often accompanied by reciprocal ST-segment depression (RC) occurring in opposite leads, whose significance has been debated for decades. The possible role of collateral circulation in promoting RC in acute STEMI has not been identified. So our aim to find the relationship between collateral circulation and RC in STEMI patients treated with primary percutaneous intervention (PPCI). METHODS: The study included 112 pts. with acute STEMI underwent PPCI. The patients divided in to 2 groups: Group (A):66 pts. with RC, Group (B):46 pts without RC. All patients subjected to history taking, ECG [localization of infarction & RC], CKMB level, transthoracic echo [LVEF%], coronary angiography &PPCI to culprit artery and assess number of diseased vessels, site of occlusion, collaterals, TIMI flow pre and post PCI. RESULTS: Patients in group A with RC had shorter time to door, P < 0.001; more frequent inferior infarctions, P < 0.001; had higher CKMB level, P < 0.001; higher LVEDD, P < 0.001; LVESD, P < 0.001and lower LVEF, P = 0.004; had multi vessel diseases P = 0.02, increase incidence of RCA as a culprit artery <0.001 compared to patients with no RC. Patients with RC had significantly higher incidence of proximal LAD occlusion, distal RCA and distal LCX compared to patients without RC. The percentage of change was 61.2 ± 12.35% for ST elevation and 50.5 ± 10.87% for reciprocal ST depression post PCI with significance difference between them, t = 3.035P = 0.0023.There was no significant correlation between collateral circulation and RC. We found four significant independent predictors of RC. They were inferior infarction (P = 0.024), RCA as a culprit vessel, (P = 0.034), low EF, (P = 0.007) and multi-vessel disease, (P = 0.022). CONCLUSION: There is no correlation between concomitant RC and presence of collateral vessels in acute STEMI patients. So the pathogenesis of reciprocal ST-segment changes result from an interplay of ischemia at distance due to multi-vessel CAD and benign mirror electrical changes not caused by collateral circulation diverting blood to ischemic area from non-diseased artery.

Upsloping ST depression: Is it acute ischemia?

We describe a patient with acute coronary syndrome, presenting with upsloping ST depression in leads I, II, V3-V6 and ST elevation in lead aVR. Coronary angiography revealed spontaneous dissection in a big, dominant left circumflex artery. No other lesions identified. During stenting of the dissection site, the distal left circumflex, supplying a large posterior descending artery was occluded, resulting in ST elevation myocardial infarction with ST elevation in lead III and aVF, but not II. This pattern is considered to represent right coronary artery infarction, rather than left circumflex infarction.

The predictive value of aVR in determining the infarct related artery during primary percutaneous coronary intervention.

BACKGROUND: Isolation of infract related artery and timely revascularisation remains vital in the setting of primary percutaneous coronary intervention. OBJECTIVES: To analyse the predictive value of ST-T changes in lead aVR in inferior myocardial infarction in terms of prognosis and timely risk stratification. METHODS: We conducted a prospective analysis of acute inferior wall myocardial infarction patients. One hundred patients were categorised into two groups according to the culprit artery: group I, right coronary artery (RCA) and group II, left circumflex coronary artery (LCX), with 50 patients in each group. A comparative study was performed between the two groups, comprising the following data outputs: electrocardiogram (ECG) changes that could help determine the culprit artery, cardiac enzyme levels, echocardiographic findings, coronary angiography findings and in-hospital complications. The same patients were divided into two groups according to the presence or absence of 1 mm ST depression in lead aVR. A comparison analysis was performed between the two groups including: cardiac enzyme levels, echocardiographic findings, coronary angiography findings and in-hospital complications. RESULTS: ST depression in aVR ≥ 1 mm predicted the LCX as a culprit artery with sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) recorded at 66%, 84%, 80.5% and 71.2%, respectively. Also, patients with ST depression in aVR ≥ 1 mm showed significantly higher cardiac enzyme levels, indicating larger infarct size, with mean peak creatinine kinase (CK) = 1560 (1057-2375) IU/L versus 970 (613-1683) IU/L, (P value = 0.014), lower ejection fraction (Ef) with mean Ef = 47.93 ±â€¯8.04 versus 54.66 ±â€¯6.52, (P value < 0.001) and more significant mitral regurgitation: 17 (41.5%) patients versus 11 (18.6%) patients (P value = 0.012). Regarding in-hospital complications, there were no significant differences. CONCLUSIONS: ST depression of >1 mm in lead aVR predicts LCX as the infarct related artery and is a predictor of poor outcome in patients with inferior myocardial infarction.

Diffuse ST segment depression and ST segment elevation in lead aVR and V1 by left circumflex artery occlusion.

The current guidelines for resting electrocardiograms of diffuse ST segment depression coupled with ST segment elevation in aVR and/or V1 that are otherwise unremarkable indicate multivessel or left main coronary artery obstruction. However, our case meets the above electrocardiogram changes, but involves left circumflex artery occlusion.

What is the predictive value of ST segment depression in inferior leads in first acute anterior myocardial infarction?

BACKGROUND: Electrical phenomenon and remote myocardial ischemia are the main factors of ST segment depression in inferior leads in acute anterior myocardial infarction (AAMI). We investigated the prognostic value of the sum of ST segment depression amplitudes in inferior leads in patients with first AAMI treated with primary percutaneous coronary intervention. (PPCI). METHODS: In this prospective analysis, we evaluated the in-hospital prognostic impact of the sum of ST segment depression in inferior leads on 206 patients with first AAMI. Patients were stratified by tertiles of the sum of admission ST segment depression in inferior leads. Clinical outcomes were compared between those tertiles. RESULTS: Univariate analysis revealed higher rate of in-hospital death for patients with ST segment depression in inferior leads in tertile 3, as compared to patients in tertile 1 (OR 9.8, 95% CI 1.5-78.2, p<0.001). After adjustment for baseline variables, ST segment depression in inferior leads in tertile 3 was associated with 5.7-fold hazard of in-hospital death (OR: 5.7, 95% CI 1.2-35.1, p<0.001). Spearman rank correlation test revealed correlation between the sum of ST segment depression amplitude in inferior leads and the sum of ST segment elevation amplitude in V1-6, L1 and aVL. Multivessel disease and additional RCA stenosis were also detected more often in tertile 3. CONCLUSION: The sum of ST segment depression amplitude in inferior leads of admission ECG in patients with first AAMI treated with PPCI provide an independent prognostic marker of in-hospital outcomes. Our data suggest the sum of ST segment depression amplitude to be a simple, feasible and clinically applicable tool for rapid risk stratification in patients with first AAMI.

Electrocadiographic Scoring Helps Predict Left Ventricular Wall Motion Abnormality Commonly Observed after Subarachnoid Hemorrhage.

BACKGROUND: Cardiac wall motion abnormality (WMA) is a common complication in patients with subarachnoid hemorrhage (SAH) and is one determinant of their prognosis. The aim of this study was to examine whether the electrocardiography (ECG) findings at admission could predict WMA commonly observed after SAH. MATERIALS AND METHODS: We studied 161 SAH patients with SAH who were hospitalized in our institution between April 2007 and November 2010. We performed bedside 2-dimensional transthoracic echocardiography and 12-lead surface ECG within 24hours of SAH onset. Each of the following ECG changes was scored as having 1 point: ST elevation, ST depression and T wave inversion. We summed up the points in every patient and compared with WMA evaluated by echocardiography. RESULTS: The study subjects were classified into 2 groups based on the presence of WMA. Multivariate analysis revealed that ST elevation, ST depression and T wave inversion were strong independent predictors of WMA. Receiver operating characteristic curve determined that the threshold value to predict WMA was 4 points (sensitivity 86.5%, specificity 83.1%, AUC 0.94, P < .0001). CONCLUSIONS: In conclusion, a novel ECG score may well predict WMA after SAH which may associate with an increased risk of mortality.

Clinical Significance of Upsloping ST Depression on Resting Electrocardiogram.

INTRODUCTION: Upsloping ST depression is generally not associated with myocardial ischemia, yet there have been published reports that suggest otherwise. CASE HISTORY: A 34-year-old pregnant female presented with chest pain and palpitations. She was found to have supraventricular tachycardia, which resolved with intravenous adenosine. Few minutes later her ECG showed upsloping ST depression in leads V4-V6 that persisted for 1 hour after the resolution of the tachycardia. The patient was discharged in stable condition with outpatient follow-up. CONCLUSION: Upsloping ST depression in resting electrocardiogram may indicate cardiac ischemia in the presence of active cardiac symptoms. In the absence of ongoing symptoms however, it may be secondary to conditions other than ischemia.

Are the QRS duration and ST depression cut-points from the Seattle criteria too conservative?

BACKGROUND: Screening athletes with ECGs is aimed at identifying "at-risk" individuals who may have a cardiac condition predisposing them to sudden cardiac death. The Seattle criteria highlight QRS duration greater than 140 ms and ST segment depression in two or more leads greater than 50 µV as two abnormal ECG patterns associated with sudden cardiac death. METHODS: High school, college, and professional athletes underwent 12 lead ECGs as part of routine pre-participation physicals. Prevalence of prolonged QRS duration was measured using cut-points of 120, 125, 130, and 140 ms. ST segment depression was measured in all leads except leads III, aVR, and V1 with cut-points of 25 µV and 50 µV. RESULTS: Between June 2010 and November 2013, 1595 participants including 297 (167 male, mean age 16.2) high school athletes, 1016 (541 male, mean age 18.8) college athletes, and 282 (mean age 26.6) male professional athletes underwent screening with an ECG. Only 3 athletes (0.2%) had a QRS duration greater than 125 ms. ST segment depression in two or more leads greater than 50 µV was uncommon (0.8%), while the prevalence of ST segment depression in two or more leads increased to 4.5% with a cut-point of 25 µV. CONCLUSION: Changing the QRS duration cut-point to 125 ms would increase the sensitivity of the screening ECG, without a significant increase in false-positives. However, changing the ST segment depression cut-point to 25 µV would lead to a significant increase in false-positives and would therefore not be justified.

The retrograde P-wave theory: explaining ST segment depression in supraventricular tachycardia by retrograde AV node conduction.

BACKGROUND: Pseudo ischemic ST segment changes during supraventricular tachycardia (SVT) are not yet fully understood. Our aim was to determine whether venticulo-atrial (VA) conduction during SVT may be a possible mechanism for ST depression (STd) in SVT. METHODS: Patients undergoing SVT ablation (2010-2012) were analyzed (n = 72).Typical atrioventricular node reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT) were included. Those with STd were compared to those without STd. VA interval length, tachycardia cycle length (TCL), and retrograde P-wave activation during SVT were assessed. Retrograde P waves arriving simultaneously with the ST segment (PWST) during SVT were considered, whenever an atrial electrogram (measured from the high right atrium) was "on time" with the ST segment. RESULTS: Patients with STd during SVT presented longer VA intervals than those without STd (VA 100 ± 37 ms vs VA 69 ± 22 ms; P = 0.006). No differences in TCL were observed (TCL 333 ± 35 ms vs TCL 360 ± 22 ms; P = 0.1). PWST was observed in 38.5% of patients with AVNRT and STd versus 0% in those without STd. The TCL was similar in both groups (355 ± 25 ms vs 334 ± 18 ms; P = 0.1). In patients with AVRT and STd, PWST was present in 81% of cases versus 0% in those without STd. The TCL was also similar (330 ± 29 ms vs 346 ± 17 ms; P = 0.1). CONCLUSIONS: STd during SVT is observed at long VA intervals when the retrograde P wave matches the ST segment, without dependence on the TCL. This suggests that STd is not necessarily rate dependent but a result of a fusion between the ST segment and the P wave.

The role of the ECG in diagnosis, risk estimation, and catheterization laboratory activation in patients with acute coronary syndromes: a consensus document.

The electrocardiogram (ECG) is the most widely used imaging tool helping in diagnosis and initial management of patients presenting with symptoms compatible with acute coronary syndrome. Acute ischemia affects the configuration of the QRS complexes, the ST segments and the T waves. The ECG should be read along with the clinical assessment of the patient. ST segment elevation (and ST depression in leads V1 -V3 ) in patients with active symptoms usually indicates acute occlusion of an epicardial artery with ongoing transmural ischemia. These patients should be triaged for emergent reperfusion therapy per current guidelines. However, many patients have ST segment elevation secondary to nonischemic causes. ST depression in leads other than V1 -V3 usually are indicative of subendocardial ischemia secondary to subocclusion of the epicardial artery, distal embolization to small arteries or spasm supply/demand mismatch. ST depression may also be secondary to nonischemic etiologies, such as left ventricular hypertrophy, cardiomyopathies, etc. Knowing the clinical scenario, comparison to previous ECG and subsequent ECGs (in cases that there are changes in the quality or severity of symptoms) may add in the diagnosis and interpretation in difficult cases. This review addresses the different ECG patterns, typically seen in patients with active symptoms, after resolution of symptoms and the significance of such changes when seen in asymptomatic patients.

Comparison of diagnostic accuracy of current left bundle branch block and ventricular pacing ECG criteria for detection of occlusion myocardial infarction.

BACKGROUND: Electrocardiographic detection of patients with occlusion myocardial infarction (OMI) can be difficult in patients with left bundle branch block (LBBB) or ventricular paced rhythm (VPR) and several ECG criteria for the detection of OMI in LBBB/VPR exist. Most recently, the Barcelona criteria, which includes concordant ST deviation and discordant ST deviation in leads with low R/S amplitudes, showed superior diagnostic accuracy but has not been validated externally. We aimed to describe the diagnostic accuracy of four available ECG criteria for OMI detection in patients with LBBB/VPR at the emergency department. METHODS: The unweighted Sgarbossa criteria, the modified Sgarbossa criteria (MSC), the Barcelona criteria and the Selvester criteria were applied to chest pain patients with LBBB or VPR in a prospectively acquired database from five emergency departments. RESULTS: In total, 623 patients were included, among which 441 (71%) had LBBB and 182 (29%) had VPR. Among these, 82 (13%) patients were diagnosed with AMI, and an OMI was identified in 15 (2.4%) cases. Sensitivity/specificity of the original unweighted Sgarbossa criteria were 26.7/86.2%, for MSC 60.0/86.0%, for Barcelona criteria 53.3/82.2%, and for Selvester criteria 46.7/88.3%. In this setting with low prevalence of OMI, positive predictive values were low (Sgarbossa: 4.6%; MSC: 9.4%; Barcelona criteria: 6.9%; Selvester criteria: 9.0%) and negative predictive values were high (all >98.0%). CONCLUSIONS: Our results suggests that ECG criteria alone are insufficient in predicting presence of OMI in an ED setting with low prevalence of OMI, and the search for better rapid diagnostic instruments in this setting should continue.

Resting ST amplitude: prognosis and normal values in an ambulatory clinical population.

BACKGROUND: There is limited data describing ST segment amplitude in apparently healthy, asymptomatic populations. We analyzed ST amplitude in the standard resting electrocardiogram (ECG) in a large, multiethnic, stable, clinical population. METHODS: We evaluated computerized ST amplitude measurements from the resting ECGs of 29,281 ambulatory outpatients collected between 1987 and 1999 at the Palo Alto, VA. With the PR interval as the isoelectric line, both elevation criteria (≥0.1 mV, ≥0.15 mV, and ≥0.2 mV) and depression criteria (≤-0.05 mV or ≤-0.1 mV), were applied. Cox-Hazard survival analysis techniques were used to demonstrate in which leads ST amplitude displacement was associated with cardiovascular (CV) death. To create a cohort without ECG patterns clearly associated with disease, we excluded ECGs with inverted T waves, wide QRS, or diagnostic Q waves and coded the remaining "normal" ECGs for ST elevation and depression to determine a normal range. RESULTS: The only ST amplitudes that were significantly and independently associated with time to CV death when adjusted for age, gender, and ethnicity were ST depression in all of the lateral leads (I, V4 -V6 ). When isolated to the inferior leads, (II and AVF), no ST amplitude criteria were associated with CV death. Among the "normal ECG" subgroup the precordial leads exhibited the greatest median ST amplitudes and the most significant differences between the leads, genders and ethnicities. CONCLUSIONS: Significant differences in ST amplitude were present in the precordial leads according to gender and ethnicity. This was particularly apparent when amplitude threshold were set for comparisons. Our findings provide the normal range for ST amplitude that when exceeded, should raise clinical concern.

Diffuse St Depression With St Elevation Avr In Acute Coronary Syndrome And Its Association With Significant Left Main Or Three Vessel Coronary Artery Disease And Its Confounders.

BACKGROUND: : Global ST depression in 8 or more leads along with ST elevation in aVR has been considered as hallmark of widespread sub-endocardial ischemia. It has been associated with left main (LM) stem or three vessel disease (3VD). But different studies have shown different results. We collected data from patients to see association of these ECG changes with significant LM stem disease and/or significant (3VD). METHODS: TIt was a prospective observational study performed at tertiary care cardiac center. All patients with acute coronary syndrome (ACS) having global ST depression and ST Elevation in aVR (that is ST depression of at least 0.5 mv in ≥8 leads along with ST elevation in aVR of at least 0.5 mv) and have undergone coronary angiogram were included. RESULTS: Our study included 404 patients with above mentioned ECG findings. We observed significant LM stem or significant 3VD in 67% (n=274), 3VD in 55% (n=222) and significant LM stem in only 29% (n=118). Risk factors like diabetes, hypertension and smoking increase probability of these ECG changes up to 40.4%, 32.1% and 33.3% for significant LM stem disease and 62.7%, 57.1% and 57.5% for significant 3VD. Magnitude of ST elevation in aVR leads ≥1 mm increase sensitivity for LM stem disease 35% and for 3VD up to 60.4% and TIMI score ≥4 up to 36.7% for significant LM stem disease and 62.5% for significant 3VD. CONCLUSIONS: : Global ST depression along with ST elevation in aVR in patients with ACS has low probability for significant LM stem intermediate probability for significant 3VD. Factors like presence of diabetes, hypertension, smoking, magnitude of ST elevation in aVR, and TIMI score improves its diagnostic yield.

Recurrent intraoperative silent ST depression responding to phenylephrine.

Intraoperative myocardial ischemia is attributed to decreased myocardial oxygen supply. We present an unusual case of recurrent, symptomless inferior wall ischemia in an apparently healthy male with no history of coronary artery disease after a spinal block. The recurring episodes were linked to tachycardia and presented with significant ST depression in Lead II with reciprocal elevation in lead aVL. The episodes responded to phenylephrine and subsided without residual sequelae.

What are the prognostic implications and factors relating to exercise induced electrocardiographic ST segment changes in the setting of a non-ischemic stress echocardiogram?

BACKGROUND: Electrocardiographic (ECG) changes during stress testing are a common and perplexing finding during non-ischemic stress echocardiography (niSE). Research has provided conflicting results regarding the implications. METHODS: SE was performed after maximal Bruce protocol treadmill exercise. RESULTS: 3020 consecutive patients, mean age 58 ± 12 years, 36% female, were followed-up for up to 9 years (mean 36 ± 21 months) post niSE. Time to first cardiac event (composite of heart failure admission, worsening New York Heart Association class, worsening ejection fraction, acute coronary syndrome, revascularization, angina or cardiovascular death) was analysed and adjusted using Cox proportional hazards regression. Prognostic significance was found with 1.5 mm of downsloping or horizontal ST depression. Adjusting for baseline differences, increased risk of composite major adverse cardiac events was shown with at least 1.5 mm of exercise induced ST depression (Hazard ratio [HR] of 2.47, 95% Confidence ratio [CI] 1.67-3.72, p < 0.0001). Patients achieving high level exercise capacity (≥13 metabolic equivalents or METs) with ST depression lower risk of cardiac events during follow-up. CONCLUSION: Patients with ST segment depression but non-ischemic stress imaging have a poorer prognosis compared to patients with niSE with normal stress ECGs. ST depression of 1.5 mm or more was established as a prognostically significance value. High exercise capacity was associated with an improved prognosis, and ECG changes in that setting can be regarded as false positives. All niSE have low risk of a cardiac event in the very short term (<12 months). Overall, ST depression during non-ischaemic stress imaging is not a benign finding.