Beta Blockers in Contemporary Cardiology: Is It Better to Cast Them Out?

Beta blockers are one of the commonest prescription drugs in medicine and they have been thought to revolutionize the treatment of heart failure (HF) with reduced ejection fraction (HFrEF) in the last century. In addition to HFrEF, they are prescribed for a variety of diseases in cardiology from hypertension to HF, angina, and stable coronary artery disease (CAD). The increased prescription of beta blockers in conditions like HF with preserved ejection fraction (HFpEF), and stable CAD may be doing more harm than good as per the data we have so far. The available data shows that beta blockers are associated with increased stroke risk and atrial fibrillation (AF) in hypertension and in patients with HFpEF, they have been associated with decreased exercise capacity. In patients with stable CAD and patients with myocardial infarction with normal systolic functions, beta blockers don't offer any mortality benefit. In this article, we critically review the common indications and the uses of beta blockers in patients with HFpEF, CAD, hypertension and AF and we propose that beta blockers are over-prescribed under the shadow of their beneficial effects in patients with HFrEF.

Electrocardiographic lead reversals.

Misplacement of cables during the recording of a 12-lead electrocardiogram [ECG] poses a non-negligible risk of creating panic and confusion at the bedside in daily clinical practice. Clinical awareness about the manifestations of commonly encountered electrode misplacements is imperative for avoiding misdiagnosis. A basic understanding of the electrophysiology behind these anomalous ECG tracings is likely to aid in prompt suspicion, accurate detection, and appropriate rectification in most cases. We discuss the abnormalities produced on 12-lead ECG tracings by the misplacement of electrode cables, with a focus on the clinical implications of the same. We suggest a mnemonic - 'SPIRAL' - as a quick screening criterion to detect commonly encountered lead reversals.

Does Cardiac Arrhythmia Predict Worse Outcome in Mild or Moderate Covid-19 Infection?

Covid-19 is a multisystem disease with the lungs being predominantly affected. Cardiac involvement is mostly seen as a rise in troponins, arrhythmias, and ventricular dysfunction. This study aimed to estimate the incidence of arrhythmias seen in Covid-19 infection and assess if arrhythmias predict worsening or mortality. Prospective observational study involving patients with mild to moderate Covid illness admitted in a tertiary care centre. Among the 85 patients (Mean age 45.8 + 14.1 years; 75.31% men), worsening of Covid-19 illness was seen in 29 (34.1%) patients. New onset arrhythmias were detected on Holter in 9 (10.5%) patients. Supraventricular tachycardia was seen in 7 (8.2%) patients of whom 6 showed worsening which was statistically significant (p-value-0.006). Risk factors associated with worsening on univariate analysis were male gender (OR [95%CI] = 6.93(1.49-32.31), p-value - 0.014), new onset supraventricular tachycardia (OR [95% CI] = 14.35 [1.64-125.94], p-value - 0.016) and D-dimer elevation (OR [95% CI] = 1.00(1.00-1.01), p-value - 0.02). On multivariate analysis D-dimer (OR [95% CI] = 1.00(1.00-1.01; p-value 0.046) and supraventricular arrhythmias (OR [95% CI] = 11.12 (1.22-101.14); p-value - 0.033) were independently associated with worsening. Covid-19 infection can lead to cardiac arrhythmias. The development of supraventricular tachycardia in patients with Covid-19 infection predicts higher morbidity and worsening.

A Pilot Study of Electrocardiographic Features in Patients with Obesity from a Tertiary Care Centre in Southern India (Electron).

Background: Obesity is associated with increased all-cause mortality and cardiovascular disease (CVD). An electrocardiogram (ECG) may be used to screen for subtle signs of CVD or altered cardiac morphology in the obese. Methodology: This observational cross-sectional analysed ECG changes in patients with obesity at a tertiary care centre in southern India. Results: One hundred and fifty adult patients with a mean (SD) BMI of 39.9 (6.7) kg/m2 were recruited in the study after excluding those with comorbidities (diabetes mellitus, systemic hypertension) or on chronic medications (ACE inhibitors). The cohort showed a female predominance (69.3%), with a mean (SD) age of 45.4 (11.2) years. Most patients exhibited a sinus rhythm (78%), with one patient showing features of first-degree conduction block. Sinus tachycardia was seen in 32 (21.3%) patients. We observed left and right ventricular hypertrophy in five (3.3%) and three (2%) patients, respectively. Observed ECG patterns included a prolonged QTc in 16 (10.7%) patients, inverted T-waves (mostly in the inferior leads) in 39 (26%) patients and ST-segment depression (predominantly in the lateral leads) in 14 (9.3%) patients. A greater prevalence was noted for morbid obesity. No deaths were reported in our cohort. Conclusions: The predominant ECG variations in this cohort included tachycardia, atrial enlargement, ventricular hypertrophy, conduction defects, LAD, features of ischemia or old infarction and repolarization abnormalities, with a greater prevalence in morbid obesity. Further studies are needed to assess the impact of weight reducing measures on reversibility of these changes and determine the association with outcomes in obese patients.

Atrial depolarization abnormalities in pulmonary sarcoidosis.

BACKGROUND: Cardiac sarcoidosis, often manifested as sudden death, can be the first manifestation of sarcoidosis. Since 12-lead electrocardiogram (ECG) is recommended as an initial screening tool for cardiac sarcoidosis, the recognition of subtle abnormalities assumes utmost significance. The objective of this study was to identify the electrocardiographic abnormalities in patients with pulmonary sarcoidosis. RESULTS: A detailed analysis of 12-lead ECGs obtained from sixty patients with histopathologically proven pulmonary sarcoidosis and no overt cardiac involvement was done. The findings were compared with those of an age-matched control group. Varying degrees of intraventricular conduction defects were common in the study group [67%], as well as the control group [57%] [P = 0.23]. There was a higher prevalence of biphasic P wave [P = 0.003] and bifid P wave [P = 0.029] in lead III and rsr' in lead aVF [P = 0.03] in the study group as compared to the control group. CONCLUSIONS: Our study demonstrates a greater prevalence of subtle ECG abnormalities in patients with pulmonary sarcoidosis as compared to patients with other forms of pulmonary disease. Atrial depolarization abnormalities were commoner in patients with pulmonary sarcoidosis.

Effects of heat stroke on surface ECG: a study on clinical outcomes.

AIMS: Classic heat stroke is associated with high in-hospital mortality and morbidity. The relation between the ECG findings in heat stroke and the clinical outcomes of these patients has not been studied. The aim of this study was to describe the electrocardiographic features in patients with classic heat stroke and to determine if there is any correlation of ECG findings with in-hospital outcomes. METHODS: We performed a retrospective study on 50 patients with classic heat stroke during summer months of 2016-2018. All 12-lead electrocardiographic recordings obtained from these patients were subjected to in-depth analysis. Statistical analysis was done to determine the correlation of electrocardiographic findings with in-hospital outcomes. RESULTS: 37 patients were in sinus rhythm, while supraventricular arrhythmias including atrial fibrillation (n=6), ectopic atrial tachycardia (n=4) and atrial flutter (n=2) were observed in the rest. There was a high prevalence of QTc prolongation, low voltage P waves, conduction defects like incomplete right bundle branch block and repolarisation abnormalities. The ratio of QRS voltage in the limb leads to that in precordial leads was ≤0.5 in nearly three-fourths of the patients. Among the observed electrocardiographic features, low P-wave voltage (<0.01 mV) in lead II was found to have statistically significant correlation with adverse in-hospital outcome (OR 8.93, p=0.04), after adjustment for clinical covariates. CONCLUSION: There was high incidence of atrial arrhythmias in patients with classic heat stroke. A low P-wave voltage (<0.01 mV) in lead II was predictive of adverse in-hospital outcome in this cohort of patients.

Devil is in the detail.

A 15-year-old girl of Asian origin, hailing from a rural agrarian background, presented with history of multiple episodes of dizziness for 3 years. The episodes were precipitated mostly by emotional and/or physical stress and relieved on lying down, with a few episodes culminating in transient loss of consciousness. As preliminary cardiac and neurological evaluation were normal, she was being treated by the primary physician as a case of probable psychogenic syncope, supported by the consistent association of the episodes with emotional stress. A detailed review of family history revealed that the premature demise of the patient's siblings which were attributed to snakebite and head trauma by the family could have been in reality sudden cardiac deaths. Treadmill test revealed exercise-induced polymorphic ventricular tachycardia confirmatory for the diagnosis of catecholaminergic polymorphic ventricular tachycardia. She was initiated on beta-blocker therapy to which she showed remarkable response.

Left ventricular structure and diastolic function by cardiac magnetic resonance imaging in hypertrophic cardiomyopathy.

OBJECTIVE: Diastolic dysfunction is common in hypertrophic cardiomyopathy (HCM) and hypertensive heart disease (HHD), but its relationships with left ventricular (LV) parameters have not been well studied. Our objective was to assess the relationship of various measures of diastolic function, and maximum left ventricular wall thickness (MLVWT) and left ventricular mass index (LVMI) in HCM, HHD and normal controls using cardiac magnetic resonance imaging (CMR). We also assessed LV parameters and diastolic function in relation to late gadolinium enhancement (LGE) and right ventricular (RV) hypertrophy in HCM. METHODS: 41 patients with HCM, 21 patients with HHD and 20 controls were studied. Peak filling rate (PFR), time to peak filling (TPF), MLVWT and LVMI were measured using CMR. LGE and RV morphology were assessed in HCM patients. RESULTS: MLVWT correlated with TPF in HCM (r=0.38; p=0.02), HHD (r=0.58; p=0.01) and controls (r=0.54; p=0.01); correlation between MLVWT and TPF was weaker in HCM than HHD. LVMI did not correlate with diastolic function. In HCM, LGE extent correlated with MLVWT (τ=0.41; p=0.002) and with TPF (τ=0.29; p=0.02). The HCM patients with RV hypertrophy had higher MLVWT (p<0.001) and TPF (p=0.03) than patients without RV hypertrophy. CONCLUSION: MLVWT correlates with diastolic function (TPF) in HCM, HHD and controls. LVMI did not show significant correlation with TPF. The diastolic dysfunction in HCM is not entirely explained by wall thickening. LGE and RV involvement are associated with worse LV diastolic function, suggesting that these may be markers of more severe underlying myocardial disarray and fibrosis that contribute to diastolic dysfunction.

Decrement Evoked Potential Mapping: Basis of a Mechanistic Strategy for Ventricular Tachycardia Ablation.

BACKGROUND: Substrate-based mapping for ventricular tachycardia (VT) ablation is hampered by its inability to determine critical sites of the VT circuit. We hypothesized that those potentials, which delay with a decremental extrastimulus (decrement evoked potentials or DEEPs), are more likely to colocalize with the diastolic pathways of VT circuits. METHODS AND RESULTS: DEEPs were identified in intraoperative left ventricular maps from 6 patients with ischemic cardiomyopathy (total 9 VTs) and were compared with late potential (LP) and activation maps of the diastolic pathway for each VT. Mathematical modeling was also used to further validate and elucidate the mechanisms of DEEP mapping. All patients demonstrated regions of DEEPs and LPs. The mean endocardial surface area of these potentials was 18±4% and 21±6%, respectively (P=0.13). The mean sensitivity for identifying the diastolic pathway in VT was 50±23% for DEEPs and 36±32% for LPs (P=0.31). The mean specificity was 43±23% versus 20±8% for DEEP and LP mapping, respectively (P=0.031). The electrograms that displayed the greatest decrement in each case had a sensitivity and specificity for the VT isthmus of 29±10% and 95±1%, respectively. Mathematical modeling studies recapitulated DEEPs at the VT isthmus and demonstrated their role in VT initiation with a critical degree of decrement. CONCLUSIONS: In this preliminary study, DEEP mapping was more specific than LP mapping for identifying the critical targets of VT ablation. The mechanism of DEEPs relates to conduction velocity restitution magnified by zigzag conduction within scar channels.