The Impact of Left Ventricular Mass on Diastolic Blood Pressure Targets for Patients With Coronary Artery Disease

Searching for the Best Machine Learning Algorithm for the Detection of Left Ventricular Hypertrophy from the ECG: A Review

Background: Left ventricular hypertrophy (LVH) is a powerful predictor of future cardiovascular events. Objectives: The objectives of this study were to conduct a systematic review of machine learning (ML) algorithms for the identification of LVH and compare them with respect to the classical features of test sensitivity, specificity, accuracy, ROC and the traditional ECG criteria for LVH. Methods: A search string was constructed with the operators "left ventricular hypertrophy, electrocardiogram" AND machine learning; then, Medline and PubMed were systematically searched. Results: There were 14 studies that examined the detection of LVH utilizing the ECG and utilized at least one ML approach. ML approaches encompassed support vector machines, logistic regression, Random Forest, GLMNet, Gradient Boosting Machine, XGBoost, AdaBoost, ensemble neural networks, convolutional neural networks, deep neural networks and a back-propagation neural network. Sensitivity ranged from 0.29 to 0.966 and specificity ranged from 0.53 to 0.99. A comparison with the classical ECG criteria for LVH was performed in nine studies. ML algorithms were universally more sensitive than the Cornell voltage, Cornell product, Sokolow-Lyons or Romhilt-Estes criteria. However, none of the ML algorithms had meaningfully better specificity, and four were worse. Many of the ML algorithms included a large number of clinical (age, sex, height, weight), laboratory and detailed ECG waveform data (P, QRS and T wave), making them difficult to utilize in a clinical screening situation. Conclusions: There are over a dozen different ML algorithms for the detection of LVH on a 12-lead ECG that use various ECG signal analyses and/or the inclusion of clinical and laboratory variables. Most improved in terms of sensitivity, but most also failed to outperform specificity compared to the classic ECG criteria. ML algorithms should be compared or tested on the same (standard) database.

Estimating Left Ventricular Mass from the Electrocardiogram across the Spectrum of LV Mass from Normal to Increased LV Mass in an Older Age Group

Objectives

To examine the relationship of QRS voltages and left ventricular (LV) mass across the spectrum of individuals with different LV mass.

Methods

Twenty QRS voltage measurements or combinations were determined in a consecutive series of 159 adults with an ECG and echocardiogram without previous myocardial infarction, left or right bundle branch block, pre-excitation, or electronic pacemaker.

Results

The four strongest and significant correlations between QRS and LV mass were S in V4, deepest S wave in any precordial lead plus S in V4, S in V3, and S in V3 plus R in AVL times QRS duration. For men, the strength of the relationships were S in V3 (F = 33.8), deepest S wave in any precordial lead plus S V4 (F = 33.7), S in V3 plus R aVL (F = 29.9), S in V4 (F = 29.79), and deepest S in precordial leads (F = 17.9). The R wave in AVL alone did not correlate with LV mass. Criteria using the R wave in lateral precordial leads did not correlate as strongly with LV mass. For women, only S in V4 significantly correlated with LV mass. Overall, the R wave voltage in limb leads (AVL I or II) did not correlate with precordial S wave amplitudes. Univariate and multivariate analysis showed that some but not all QRS voltages correlated with each other. In multivariate analysis, using only single variables and not combination of QRS variables, the only significant relationship between QRS voltage and left ventricular mass was for men the S in V3 (p = 0.04) and for women S in V4 (p = 0.016) and R in V6 (p = 0.04).

Conclusion

The S wave in V3 and V4 correlate most strongly with LV mass while the R wave in limb leads, including AVL, do not correlate.

The baseline and repeated measurements of DBP to assess in-hospital mortality risk among critically ill patients with acute myocardial infarction: A retrospective cohort study

Changes in diastolic blood pressure (DBP) are common in patients with acute myocardial infarction (AMI). The relationship between the dynamic change of DBP and in-hospital mortality among patients with AMI remains unclear. This study aimed to explore the importance of DBP during disease development among patients with AMI. We performed a retrospective cohort study involving patients from the Medical Information Mart for Intensive Care III database, which included > 40,000 patients admitted to the intensive care unit (ICU). Overall, 3209 adult AMI admissions were identified. We extracted the clinical and laboratory information in the patients with AMI. Cox proportional hazards models were used to evaluate the prognostic values of baseline DBP. We used the generalized additive mixed model (GAMM) to compare trends in DBP over time among survivors and non-survivors, after adjusting for potential confounders. During the ICU stay, 189 patients died (mortality rate, 6.36%). The age of each non-survivor together with the variations in DBP over time from admission to the time of death is of great importance to the scientific community. Cox multivariable regression analysis displayed that after adjusting for confounding factors, ascended baseline DBP was an important hazard factor for hospital deaths (hazard ratio, 1.02; 95% confidence interval, 1.01-1.03; P = .003). Based on GAMM, DBP in the death group was markedly lower than that of the surviving group. Moreover, the difference between the two groups showed an increasing trend within 3 days after ICU admission. After adjusting for various variables, the results were stable. DBP significantly contributed to in-hospital mortality among patients with AMI. There was a nonlinear correlation between baseline DBP and in-hospital mortality among patients with AMI, and the DBP of the non-survivors decreased within the first 3 days after ICU admission. However, the causality cannot be deduced from our data.

Physiologically personalized coronary blood flow model to improve the estimation of noninvasive fractional flow reserve

PURPOSE

Coronary outlet resistance is influenced by the quantification and distribution of resting coronary blood flow. It is crucial for a more physiologically accurate estimation of fractional flow reserve (FFR) derived from computed tomography angiography (CTA), referred to as FFRCT. This study presents a physiologically personalized (PP)-based coronary blood flow model involving the outlet boundary condition (BC) and a standardized outlet truncation strategy to estimate the outlet resistance and FFRCT.

METHODS

In this study, a total of 274 vessels were retrospectively collected from 221 patients who underwent coronary CTA and invasive FFR within 14 days. For FFRCT determination, we have employed a PP-based outlet BC model involving personalized physiological parameters and left ventricular mass (LVM) to quantify resting coronary blood flow. We evaluated the improvement achieved in the diagnostic performance of FFRCT by using the PP-based outlet BC model relative to the LVM-based model, with respect to the invasive FFR. Additionally, in order to evaluate the impact of the outlet truncation strategy on FFRCT, 68 vessels were randomly selected and analyzed independently by two operators, by using two different outlet truncation strategies at 1-month intervals.

RESULTS

The per-vessel diagnostic performance of the PP-based outlet BC model was improved, based on invasive FFR as reference, compared to the LVM-based model: (i) accuracy/sensitivity/specificity: 91.2%/90.4%/91.8% versus 86.5%/84.6%/87.6%, for the entire dataset of 274 vessels, (ii) accuracy/sensitivity/specificity: 88.7%/82.4%/90.4% versus 82.4%/ 76.5%/84.0%, for moderately stenosis lesions. The standardized outlet truncation strategy showed good repeatability with the Kappa coefficient of 0.908.

CONCLUSIONS

It has been shown that our PP-based outlet BC model and standardized outlet truncation strategy can improve the diagnostic performance and repeatability of FFRCT.

Potential impact of the 2017 ACC/AHA guideline on high blood pressure in normotensive patients with stable coronary artery disease: insights from the CLARIFY registry

Aims

The 2017 American College of Cardiology/American Heart Association (ACC/AHA) guideline on high blood pressure (BP) lowered the threshold defining hypertension and BP target in high-risk patients to 130/80 mmHg. Patients with coronary artery disease and systolic BP 130–139 mmHg or diastolic BP 80–89 mmHg should now receive medication to achieve this target. We aimed to investigate the relationship between BP and cardiovascular events in ‘real-life’ patients with coronary artery disease considered as having normal BP until the recent guideline.

Methods and results

Data from 5956 patients with stable coronary artery disease, no history of hypertension or heart failure, and average BP <140/90 mmHg, enrolled in the CLARIFY registry (November 2009 to June 2010), were analysed. In a multivariable-adjusted Cox proportional hazards model, after a median follow-up of 5.0 years, diastolic BP 80–89 mmHg, but not systolic BP 130–139 mmHg, was associated with increased risk of the primary endpoint, a composite of cardiovascular death, myocardial infarction, or stroke (hazard ratio 2.15, 95% confidence interval 1.22–3.81 vs. 70–79 mmHg and 1.12, 0.64–1.97 vs. 120–129 mmHg). No significant increase in risk for the primary endpoint was observed for systolic BP <120 mmHg or diastolic BP <70 mmHg.

Conclusion

In patients with stable coronary artery disease defined as having normal BP according to the 140/90 mmHg threshold, diastolic BP 80–89 mmHg was associated with increased cardiovascular risk, whereas systolic BP 130–139 mmHg was not, supporting the lower diastolic but not the lower systolic BP hypertension-defining threshold and treatment target in coronary artery disease.

ClinicalTrials identifier

ISRCTN43070564.

2018 Korean Society of Hypertension Guidelines for the management of hypertension: part II-diagnosis and treatment of hypertension

The standardized techniques of blood pressure (BP) measurement in the clinic are emphasized and it is recommended to replace the mercury sphygmomanometer by a non-mercury sphygmomanometer. Out-of-office BP measurement using home BP monitoring (HBPM) or ambulatory BP monitoring (ABPM) and even automated office BP (AOBP) are recommended to correctly measure the patient’s genuine BP. Hypertension (HTN) treatment should be individualized based on cardiovascular (CV) risk and the level of BP. Based on the recent clinical study data proving benefits of intensive BP lowering in the high risk patients, the revised guideline recommends the more intensive BP lowering in high risk patients including the elderly population. Lifestyle modifications, mostly low salt diet and weight reduction, are strongly recommended in the population with elevated BP and prehypertension and all hypertensive patients. In patients with BP higher than 160/100 mmHg or more than 20/10 mmHg above the target BP, two drugs can be prescribed in combination to maximize the antihypertensive effect and to achieve rapid BP control. Especially, single pill combination drugs have multiple benefits, including maximizing reduction of BP, minimizing adverse effects, increasing adherence, and preventing cardiovascular disease (CVD) and target organ damage.

Hypertension and patients with acute coronary syndrome: Putting blood pressure levels into perspective

Arterial hypertension is a well-established cardiovascular risk factor, and blood pressure (BP) control has largely improved the prognosis of hypertensive patients. A number of studies have assessed the role of BP levels in the prognosis of patients with acute coronary syndromes. Pathophysiologic links of hypertension to acute myocardial infarction (MI) include endothelial dysfunction, autonomic nervous system dysregulation, impaired vasoreactivity, and a genetic substrate. A history of hypertension is highly prevalent among patients presenting with MI, and some, but not all, studies have associated it with a worse prognosis. Some data support that low levels of admission and in-hospital BP may indicate an increased risk for subsequent events. Risk scores used in patients with MI have, therefore, included BP levels and a history of hypertension in their variables. Of note, good long-term BP control, ideally initiated prior to discharge, should be pursued in order to improve secondary prevention.

A patient-specific approach to assessing blood pressure management in patients with hypertension and coronary artery disease

The objective was to improve the management of patients with hypertension (HTN) and coronary artery disease (CAD), utilizing a model which integrates 3 determinants of coronary blood flow (CBF)-CAD severity, diastolic blood pressure (DBP), and left ventricular (LV) mass. We validated non-parametric equations for CBF estimation in a consecutive patient sample (N = 81) with HTN and CAD. There was a highly significant correlation (r = .565; P < .01) between clinical DBP and estimated CBF. Greater LV mass and more severe CAD shifted the relationship towards less CBF at the same DBP. LV mass was more critical when DBP >70 mm Hg. Estimated changes in CBF at different DBP considering the severity of CAD and LV mass can be calculated. In summary, the severity of CAD from coronary CT or coronary angiography combined with LV mass from echocardiography permits clinicians to guide the extent of, or target for, DBP to avoid seriously compromising CBF.

Hypertension Canada's 2017 Guidelines for Diagnosis, Risk Assessment, Prevention, and Treatment of Hypertension in Adults

Hypertension Canada provides annually updated, evidence-based guidelines for the diagnosis, assessment, prevention, and treatment of hypertension. This year, we introduce 10 new guidelines. Three previous guidelines have been revised and 5 have been removed. Previous age and frailty distinctions have been removed as considerations for when to initiate antihypertensive therapy. In the presence of macrovascular target organ damage, or in those with independent cardiovascular risk factors, antihypertensive therapy should be considered for all individuals with elevated average systolic nonautomated office blood pressure (non-AOBP) readings ≥ 140 mm Hg. For individuals with diastolic hypertension (with or without systolic hypertension), fixed-dose single-pill combinations are now recommended as an initial treatment option. Preference is given to pills containing an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker in combination with either a calcium channel blocker or diuretic. Whenever a diuretic is selected as monotherapy, longer-acting agents are preferred. In patients with established ischemic heart disease, caution should be exercised in lowering diastolic non-AOBP to ≤ 60 mm Hg, especially in the presence of left ventricular hypertrophy. After a hemorrhagic stroke, in the first 24 hours, systolic non-AOBP lowering to < 140 mm Hg is not recommended. Finally, guidance is now provided for screening, initial diagnosis, assessment, and treatment of renovascular hypertension arising from fibromuscular dysplasia. The specific evidence and rationale underlying each of these guidelines are discussed.

Considerations in Understanding the Coronary Blood Flow- Left Ventricular Mass Relationship in Patients with Hypertension

Abstract: Background: Coronary blood flow (CBF) is essential for optimal cardiac performance and to maintain myocardial viability. There is considerable ambiguity concerning CBF in hypertension.

Objective: To investigate the relationship between CBF and left ventricular (LV) mass in persons with hypertension.

Methods: OvidSP Medline was systematically searched. Eligible articles assessed CBF, and LV mass in adults with and without hypertension (HTN).

Results: Eleven studies met the entry criteria. All 8 studies reported an increase in CBF (ml/min) for persons with hypertension (N=212) compared to individuals without hypertension (N=150). Meta-analysis showed a significant and 2.88 fold higher CBP in hypertension. Six studies adjusted CBF for LV mass; of which 4 studies reported a reduction in CBF. Meta-analysis showed a significant decrease in CBF/g LV mass in hypertension. The two studies that did not show a decrease in CBF, used the argon chromatographic method to measure coronary sinus blood flow suggesting this methodology may have influenced the results. Using the mean CBF in normotensive group to construct the expected CBF according to LV mass, reported CBF in HTN was progressively less than expected In two studies, (N=142), there was a significant inverse correlation between LV mass and CBF/ g LV mass. Multivariate analysis (three studies) consistently found a highly significant independent relationship between LV mass and CBF after considering age, sex, heart rate and several other factors.

Conclusion: Hypertension is associated with a reduction in CBF adjusted for LV mass with a highly significant inverse association between CBF and LV mass. Clinicians should be aware that patients with hypertension are at greater risk for myocardial ischemia should develop other factors that limit CBF or myocardial oxygen delivery.