Clinical significance of R-wave amplitude in lead V1 and inferobasal myocardial infarction in patients with inferior wall myocardial infarction

OBJECTIVE

To assess electrocardiogram (ECG) for risk stratification in inferior ST-elevation myocardial infarction (STEMI) patients within 24 h.

METHODS

Three hundred thirty-four patients were divided into four ECG-based groups: Group A: R V1 <0.3 mV with ST-segment elevation (ST↑) V7-V9, Group B: R V1 <0.3 mV without ST↑ V7-V9, Group C: R V1 ≥0.3 mV with ST↑ V7-V9, and Group D: R V1 ≥0.3 mV without ST↑ V7-V9.

RESULTS

Group A demonstrated the longest QRS duration, followed by Groups B, C, and D. ECG signs for right ventricle (RV) infarction were more common in Groups A and B (p < .01). ST elevation in V6, indicative of left ventricle (LV) lateral injury, was more higher in Group C than in Group A, while the ∑ST↑ V3R + V4R + V5R, representing RV infarction, showed the opposite trend (p < .05). The estimated LV infarct size from ECG was similar between Groups A and C, yet Group A had higher creatine kinase MB isoform (CK-MB; p < .05). Cardiac troponin I (cTNI) was higher in Groups A and C than in B and D (p < .05 and p = .16, respectively). NT-proBNP decreased across groups (p = .20), with the highest left ventricular ejection fraction (LVEF) observed in Group D (p < .05). Group A notably demonstrated more cardiac dysfunction within 4 h post-onset.

CONCLUSIONS

For inferior STEMI patients, concurrent R V1 <0.3 mV with ST↑ V7-V9 suggests prolonged ventricular activation and notable myocardial damage. RV infarction's dominance over LV lateral injury might explain these observations.

Wandering ST-Segment in Acute Coronary Syndrome: The Einthoven's Twist

Interpretation of the ST-segment axis in ST-elevation myocardial infarction (STEMI) plays a crucial role in identifying the culprit artery and optimizing revascularization strategies. In certain conditions, the ST-segment axis may abruptly change during management, creating diagnostic confusion, provoking unnecessary workups, and causing treatment delays. Some reported causes of wandering ST-segment include lead misplacement, progressive injury, coronary vasospasm, migration of the thrombus, and aortic dissection. Here we describe two exciting cases of wandering ST-segment axis in acute coronary syndrome and its management.

Autonomic Responses During Acute Anterior Versus Inferior Myocardial Infarction: A Systematic Review and Meta-Analysis

Autonomic responses elicited by myocardial infarction vary depending on the site of injury, but accurate assessment using heart rate variability during the acute phase is limited. We systematically searched PubMed without language restrictions throughout July 2023. We reviewed studies reporting autonomic indices separately for anterior and inferior infarcts, followed by a meta-analysis of those reporting the standard deviation of the inter-beat interval between normal sinus beats during the initial 24 hours after the onset of symptoms. Six studies were included, comprising 341 patients (165 anterior, 176 inferior infarcts), all with satisfactory scores on the Newcastle-Ottawa quality scale. The estimated average of the standardized mean difference (based on the random-effects model) was -0.722 (95% confidence intervals: -0.943 to -0.501), which differed from zero (z=-6.416, p<0.0001). This finding indicates sympathetic and vagal dominance during acute anterior and inferior infarcts, respectively, with excessive responses likely contributing to early arrhythmogenesis. Despite the amelioration of autonomic dysfunction by revascularization, infarct location should be considered when commencing β-adrenergic receptor blockade, especially after delayed procedures.

COVID-19-Associated Disseminated Intravascular Coagulopathy Presenting As Inferior ST-Segment Elevation Myocardial Infarction

Disseminated intravascular coagulopathy (DIC) is infrequently associated with COVID-19 infection. COVID-19 infection can predispose to thrombotic events through inflammation and microvascular injury. DIC is rarely associated with coronary artery disease, especially myocardial infarction (MI). In this case report, we present an uncommon case of a patient with concurrent DIC and MI in the setting of COVID-19 infection. A 73-year-old male patient with no known cardiovascular risk factor presented with syncope. Assessment in the field by emergency medical service (EMS) showed the patient had a third-degree atrioventricular block and a heart rate of 40 beats per minute. He was given atropine and transcutaneously paced. Upon admission, he was found to have an inferior wall ST-elevation myocardial infarction (STEMI) and tested positive for COVID-19. Cardiac catheterization was performed urgently and revealed triple vessel disease. Attempts to revascularize the vessels were unsuccessful. He subsequently developed cardiogenic shock. He was started on multiple pressor support. Laboratory workup was suggestive of DIC, and he later developed multiorgan failure. Continuous renal replacement therapy was initiated but failed due to persistent thrombosis of the dialysis access. Despite all measures, the patient developed cardiac arrest and passed away on the third day of hospitalization. Our understanding of COVID-19 and its complications has grown exponentially since the beginning of the pandemic. The pro-inflammatory state induced by the disease creates a hypercoagulable state that may result in thrombotic complications, including MI. In severe cases, a consumptive coagulopathy may develop, leading to DIC. This unique case report seeks to highlight the importance of staying vigilant about the potential complications of MI and DIC induced by COVID-19 so that prompt diagnosis can be made to reduce morbidity and mortality in these patients.

Subepicardial burn injuries in bullfrog heart induce electrocardiogram changes mimicking inferior wall myocardial infarction

Using bullfrog hearts, we previously reproduced a ST segment elevation in electrocardiogram (ECG), mimicking human ischemic heart disease. In the present study, by inducing subepicardial burn injuries on the inferior part of the frog heart ventricle, we could reproduce typical ECG changes observed in human inferior wall myocardial infarction, such as the marked elevation of the ST segments in inferior limb leads (II, III, aVF) and their reciprocal depression in the opposite limb leads (I, aVL). Due to the decrease in Na⁺/K⁺-ATPase protein expression, the resting membrane potential of injured cardiomyocytes shifted toward depolarization. Such induced electrical difference between the injured and intact cardiomyocytes was thought to be responsible for the creation of “currents of injury” and the subsequent ST segment changes.

Wrapped Left Anterior Descending Artery Presenting As Inferior Myocardial Infarction: Case Report and Review of the Literature

Acute occlusion of the left anterior descending (LAD) coronary artery generally results in ST-segment elevation in the anterior leads of the electrocardiogram and reciprocal ST-segment depression in the inferior leads. We present a case of LAD occlusion presenting as inferior wall ST-segment elevation myocardial infarction.

Inferior ST-segment Elevation Myocardial Infarction due to a Proximal "Wrap around" Left Anterior Descending Coronary Artery Occlusion: A Case Report

Inferior ST-segment myocardial infarction (STEMI) is often due to acute occlusion of the right coronary artery (RCA) or left circumflex artery (LCx). Anatomically, distal occlusion of a dominant left anterior descending artery (LAD) wrapping around the apex supplying posterior descending artery (PDA) can also lead to inferior wall MI. The occurrence of inferior MI with LAD occlusion is underappreciated. We are presenting a case of proximal LAD occlusion leading to inferior wall MI in the presence of non-occlusive right coronary artery (RCA). Physicians should keep in mind the possibility of inferior myocardial infarction with LAD occlusion and interventional cardiologists should perform a complete angiogram to identify the faulty lesion in inferior STEMI before deciding on a RCA or LCx as the culprit artery. Isolated IWMI (inferior wall myocardial infarction) from proximal occlusion of the wrapped around LAD as noted in our patient is a rare occurrence.

Frequency of Right Ventricular Infarction in Inferior Wall Myocardial Infarction

Background Ischemic heart disease, particularly inferior wall myocardial infarction (IWMI), is a significant issue in cardiac health. It can further add up to the morbidity and mortality when it is associated with right ventricular infarction (RVI). Elevated ST-segment elevations in the right chest lead number, three (V3R), and four (V4R), can be used to diagnose right ventricular infarction (RVI). The odds of RVI can be identified according to age groups, gender, and risk factors, including diabetes, hypertension, and smoking. This can help in the prevention of right ventricular infarct and its complications by controlling the risk factors which affect the outcome the most. Methods A sample of 1000 patients (n=1000) with acute IWMI was evaluated for the incidence of accompanying right ventricular infarct. These patients were then assessed for various known risk factors of myocardial infarction. Results Comparing the incidence of RVI against various risk factors, we found that there is an increased incidence of RVI in patients with risk factors that include hypertension and smoking.  Conclusions The study suggests that IWMI can be accompanied by RVI in almost one-third of the cases, (36% in our study). The odds of RVI are highest in patients of hypertension, and the timely control of certain risk factors will result in reduced incidence and hence the complication associated with right ventricular infarction.

Interrelation of Cardiovascular Diseases with Anaerobic Bacteria of Subgingival Biofilm

Aims:

The aim of this study is to study the colonization of subgingival biofilm (SGB) with periodontopathogenic bacteria species and endothelium-dependent vasodilation in patients with coronary heart disease and concomitant periodontitis.

Subjects and Methods:

Forty-five patients with cardiovascular diseases (CVDs) were examined – 28 women (62%) and 17 men (38%) aged 53–76 years, including 15 patients with acute myocardial infarction (AMI), 15 patients with exertional angina (pectoris), and 15 patients with chronic periodontitis (CP) without CVD. Dental and cardiological health conditions were determined, a biochemical blood test was conducted, endothelium-dependent vasodilation in the brachial artery was measured, and DNA of periodontopathogenic bacteria in SGB was detected.

Results:

A reliable interrelation between the colonization of SGB with periodontopathogenic bacteria and development of AMI was established. In AMI patients, the frequency of Porphyromonas gingivalis, Tannerella forsythia, and Aggregatibacter actinomycetemcomitans detection was significantly higher than in the group of participants without cardiovascular disease. The presence of P. gingivalis and A. actinomycetemcomitans in patients with CP directly correlated with severity of periodontal tissue destruction. Endothelium-dependent vasodilation in the brachial artery moderately correlated with patient's cardiological condition (r = 0.3284), biochemical markers of atherosclerosis development (r = 0.6465), and frequency of P. intermedia detection in periodontal pockets (r = 0.3828).

Conclusions:

Periodontal status in patients with AMI is characterized by unsatisfactory and poor hygiene, increased indices of bleeding on probing, and periodontal pocket depth in comparison to groups of patients with angina pectoris and CP without cardiovascular pathology.

Electrocardiogram criteria of limb leads predicting right coronary artery as culprit artery in inferior wall myocardial infarction: A meta-analysis

BACKGROUND

Prior studies have proposed several electrocardiogram (ECG) criteria in limb leads for identifying the culprit coronary artery (CCA) in patients with acute inferior wall myocardial infarction (IWMI). The aim of our study was to conduct an evidence-based evaluation and test accuracy comparison of these criteria.

METHODS

We searched the PubMed, Embase, and Ovid. Eligible studies to assess the diagnostic performance of ECG criteria predicting CCA in IWMI were reviewed for inclusion. A diagnostic meta-analysis of bivariate approach was performed for pooled estimates of sensitivity and specificity, and meta-regression was implemented to investigate sources of heterogeneity.

RESULTS

Twenty-four studies with 4431 unique participants met the inclusion criteria. The pooled sensitivity and specificity for ST-segment elevation (STE) in III > II, ST-segment depression (STD) in I, STD in aVL, STD in aVL > I, STE in III > II, and STD in aVL > I were 0.91 (0.88-0.94) and 0.69 (0.53-0.81), 0.80 (0.73-0.87) and 0.69 (0.62-0.76), 0.90 (0.81-0.95) and 0.41 (0.22-0.62), 0.84 (0.75-0.91) and 0.72 (0.48-0.88), and 0.79 (0.62-0.90) and 1.00 (0.37-1.00), respectively. Heterogeneity investigation showed that whether multi-vessel diseased patients were excluded, sample size, publication year, etc., could influence the diagnostic performance.

CONCLUSION

STE in III > II performed better than other criteria for predicting RCA as CCA in IWMI, and STE in III > II and STD in aVL > I were potential and simple algorithms. ECG could be an effective tool to identify the CCA, but future studies are clearly needed to address the potential of diagnostic and prognostic value.

Short-term outcome of acute inferior wall myocardial infarction with emphasis on conduction blocks: a prospective observational study in Indian population

OBJECTIVE

The primary aim of the present study was to evaluate the complications, particularly conduction blocks, subsequent morbidity and mortality, and effect of thrombolytic therapy in Indian patients with inferior wall myocardial infarction (IWMI).

METHODS

This was a prospective, observational, single-center study conducted at LPS Institute of Cardiology, Kanpur, from December 2011 to May 2014. Patients who presented with typical chest pain and were subsequently diagnosed by standardized diagnostic criteria as having IWMI were enrolled. Patients were grouped on basis of conduction abnormalities, right ventricular (RV) infarction and thrombolytic treatment. Each group was analyzed for comparison of complication profile and mortality.

RESULTS

Of 573 patients with IWMI enrolled in the study (mean age: 58.90±12.3 years), 81.2% were male, 225 (39.3%) had conduction blocks, and 189 (32.9%) had RV infarction. In patients with conduction blocks, mortality occurred in 27 patients (12.0%) in contrast to 3.4% of patients without conduction block (p<0.03). Also, there were 27 cases of in-hospital mortality in patients with RV infarction compared with 9 cases in patients without RV infarction (p<0.01). Thrombolytic therapy significantly reduced mortality in patients with IWMI (p<0.001). A significant reduction was observed in cardiogenic shock (p=0.002), severe mitral regurgitation (p=0.007), and left ventricular failure (p<0.001) in patients undergoing thrombolytic therapy.

CONCLUSION

In Indian patients with IWMI, incidence of conduction blocks was higher than previously reported studies. Major complications such as atrioventricular block and RV infarction are associated with increased mortality and poor clinical outcomes. Thrombolytic therapy has a beneficial role in reduction of mortality rate and other complications.

Neutrophil/lymphocyte ratio is associated with right ventricular dysfunction in patients with acute inferior ST-segment elevation myocardial infarction

BACKGROUND

Acute inferior ST-segment elevation myocardial infarction (STEMI) is associated with increased in-hospital morbidity and mortality particularly among patients with coexisting right ventricular (RV) involvement. High neutrophil to lymphocyte ratio (NLR) is an independent predictor of major adverse cardiac events and mortality in patients with myocardial infarction. This study evaluated the relationship between the NLR and RV dysfunction (RVD) in patients with inferior STEMI who underwent primary percutaneous coronary intervention (PCI).

METHODS

A total of 213 subjects with inferior STEMI were divided into two groups according to the presence of RVD. The groups were compared according to NLR and receiver operating characteristic (ROC) analysis was performed to access the predictability of NLR on having RVD.

RESULTS

The NLR was significantly higher in the group with RVD compared to that without RVD (p < 0.001). In ROC analysis, NLR > 3.5 predicted RVD with sensitivity of 83% and specificity of 55%. In a multivariate regression analysis, NLR remained an independent predictor of RVD (OR 1.55, 95% CI 1.285-1.750, p < 0.001).

CONCLUSIONS

NLR was an independent predictor of RVD in patients with inferior STEMI undergoing primary PCI.

Echocardiographic assessment of right ventricular function in inferior wall myocardial infarction and angiographic correlation to proximal right coronary artery stenosis

BACKGROUND

Presence of right ventricular (RV) infarction imposes a higher risk of adverse events in inferior wall myocardial infarction (IWMI). In this study, we attempted to correlate various indices of RV function assessed by echocardiography with presence of a proximal right coronary artery (RCA) stenosis in patients with first episode of acute IWMI.

METHODS

In a prospective study, patients with first episode of acute IWMI underwent echocardiographic assessment within 24 h of symptom onset and indices of RV function viz. RV fractional area change (RVFAC), tricuspid annular plane systolic excursion (TAPSE), myocardial performance index (MPI) and tissue Doppler velocities from RV free wall were measured. Patients who underwent coronary angiogram (CAG) within one month and they were classified into group 1 and group 2 based on the presence or absence, respectively, of a significant proximal RCA stenosis.

RESULTS

There were 90 patients with first episode of IWMI of which 67 patients underwent CAG. There was significant difference between group 1 (n = 26) and group 2 (n = 41) in TAPSE (13.5 ± 1.3 vs 21.3 ± 1.7, p < 0.001), MPI by tissue Doppler (0.87 ± 0.1 vs 0.55 ± 0.2, p < 0.001) and in tissue Doppler systolic velocity from RV free wall (S' 9.8 ± 1.1 vs 15.0 ± 1.5, p < 0.001). There was a good interobserver correlation for TAPSE, MPI by TDI, and S' velocity. TAPSE ≤ 16 (sensitivity 93%, specificity 100%), MPI-TDI ≥ 0.69 (sensitivity 94.7%, specificity 93.5%), S ≤ 12.3 (sensitivity 90.3%, specificity 94.3%) were useful in predicting presence of proximal RCA stenosis.

CONCLUSION

RV function indices like TAPSE, MPI-TDI and S' velocity are useful in predicting proximal RCA stenosis in first episode of acute IWMI.

Myocardial bridging of the left anterior descending coronary artery in acute inferior wall myocardial infarction

BACKGROUND

We observed marked myocardial bridging of the left anterior descending coronary artery (LAD) in the acute stages of inferior wall myocardial infarction (MI) in a group of patients who developed shock despite successful reperfusion of the infarct-related lesion (IRL).

HYPOTHESIS

The purpose of this study was to elucidate the clinical significance of myocardial bridging in patients with inferior wall MI and shock.

METHODS

The study group consisted of 53 patients with single-vessel disease of the right coronary artery, who underwent coronary angiography for acute inferior wall MI. Clinical characteristics, coronary angiographic findings, and left ventricular function during the chronic phase were compared between the patients who developed shock (the shock group) and those who did not (the non-shock group). In addition, a multiple logistic analysis was performed to identify independent predictors of shock in patients with acute inferior wall MI.

RESULTS

Reperfusion of the IRL was obtained in all 53 patients. The incidence of myocardial bridging of the LAD, the incidence of right ventricular MI, the peak creatine phosphokinase (CPK-MB). the pulmonary capillary wedge pressure, and the prevalence of pulmonary congestion seen on chest roentgenogram were significantly higher in the shock group than in the non-shock group. Myocardial bridging (p = 0.0018), right ventricular MI (p = 0.0374), and peak CPK-MB (p = 0.0189) were identified as independent predictors of shock in acute inferior wall MI.

CONCLUSION

This study suggests that myocardial bridging plays a role in left ventricular function in the acute stage of inferior wall MI.

Atrial natriuretic peptide levels after different types of inferior wall myocardial infarction

BACKGROUND

Atrial natriuretic peptide (ANP) is released from cardiac atrium secondary to increased atrial pressure. The plasma levels of ANP have been found to be related to short- and long-term prognosis after acute myocardial infarction (MI). The purpose of the present study was to investigate the plasma levels of ANP in three groups of patients with inferior wall acute MI classified according to ST-segment depression in the precordial leads.

METHODS

The study population consisted of 18 patients with inferior wall acute MI classified into three types: Type 1 = no precordial ST-segment depression (7 patients), Type 2 = sum of ST-segment depression in leads V1 to V3 equal to or more than the sum of ST-segment depression in leads V4 to V6 (4 patients), and Type 3 = maximal precordial ST-segment depression in leads V4 to V6 (7 patients).

RESULTS

Radioimmunoassay showed that plasma ANP levels were significantly higher in patients with Type 3 acute inferior wall myocardial infarction compared with those with Types 1 and 2 (313.1 +/- 233, 73.0 +/- 27.5), and 84 +/- 32.7 pg/ml, respectively, p = 0.018).

CONCLUSIONS

Plasma ANP levels are higher in patients with Type 3 acute inferior wall MI compared with patients with Types 1 and 2. These findings, together with earlier ones, may contribute to our understanding of the pathophysiology of the presence of ST-segment depression in the precordial leads in inferior wall acute MI.