Usefulness of Blunted Heart Rate Reserve as an Imaging-Independent Prognostic Predictor During Dipyridamole Stress Echocardiography

Stress Echocardiography by the ABCDE Protocol ln the Assessment of Prognosis of Stable Coronary Heart Disease

AIM

To assess the role of clinical indicators and parameters of stress echocardiography performed according to an extended protocol as predictors for the occurrence of a composite cardiovascular endpoint (CCVEP) in IHD.

MATERIAL AND METHODS

The study included 186 patients (60.2% men, mean age 60.6±9.9 years) with an established (n=73; 39.2%) and suspected (60.8%) diagnosis of IHD. Stress EchoCG with adenosine triphosphate (38.2%), transesophageal pacing (15.1%), dobutamine (2.6%), and bicycle ergometry on a recumbent ergometer (44.1%) was performed. The stress EchoCG protocol included assessment of regional wall motion abnormalities (WMA), B-lines, LV contractile reserve (CTR), coronary reserve (CR), and heart rate reserve. The median follow-up period was 13 [9; 20] months. The composite CCVEP included death from cardiovascular diseases and their complications, acute coronary syndrome, and revascularization and was defined at the first of these events. Statistical analysis was performed with the Statistica 16.0 and SPSS Statistics 23.0 software packages. Differences were considered statistically significant at p<0.05.

RESULTS

Invasive or noninvasive coronary angiography was performed in 90.3% of patients; obstructive coronary disease (stenosis ≥50%) was detected in 67.9% of cases. During the follow-up period, 58 (31.2%) patients had cardiovascular complications. The risk of developing CCVEP was associated with the pretest probability (PTP) of ischemic heart disease (odds ratio, OR, 1.05; 95% confidence interval, CI, 1.02-1.08), dyslipidemia (DLP) (OR 0.40; 95% CI 0.20-0.82), carotid atherosclerosis (OR 0.39; 95% CI 0.18-0.86), LV ejection fraction (OR 0.96; 95% CI 0.93-0.99), appearance at peak stress of new significant (2 LV segments or more) regional WMAs (OR 0.32; 95% CI 0.18-6.55), decreased LV CTR (OR 0.46; 95% CI 0.27-0.79) and CR (OR 0.33; 95% CI 0.18-0.61); p<0.05 for all. In a multivariate analysis with Cox regression, the model with clinical indicators included PTP of IHD (OR 1.04; 95% CI 1.01-1.07; p=0.01) and DLP (OR 0.14; 95% CI 0.02-1.01; p=0.05) as predictors. The model with stress EchoCG parameters included the appearance of new significant WMAs (OR 0.33, 95% CI 0.16-0.65; p=0.001) and reduced <2.0 CR (OR 0.44; 95% CI 0.24-0.82; p=0.01). A comparative analysis of Kaplan-Meier curves confirmed statistically significant differences in the dynamics of the CCVEP occurrence depending on the absence or presence of hemodynamically significant WMAs and/or reduced CR during stress EchoCG (p<0.01).

CONCLUSION

Reduced LV CR and WMA during stress EchoCG in patients with suspected or confirmed IHD are significant independent predictors for the CCVEP occurrence. Among clinical indicators, PTP of IHD and DLP are of the greatest importance for prognosis.

The clinical use of stress echocardiography in chronic coronary syndromes and beyond coronary artery disease: a clinical consensus statement from the European Association of Cardiovascular Imaging of the ESC

Since the 2009 publication of the stress echocardiography expert consensus of the European Association of Echocardiography, and after the 2016 advice of the American Society of Echocardiography-European Association of Cardiovascular Imaging for applications beyond coronary artery disease, new information has become available regarding stress echo. Until recently, the assessment of regional wall motion abnormality was the only universally practiced step of stress echo. In the state-of-the-art ABCDE protocol, regional wall motion abnormality remains the main step A, but at the same time, regional perfusion using ultrasound-contrast agents may be assessed. Diastolic function and pulmonary B-lines are assessed in step B; left ventricular contractile and preload reserve with volumetric echocardiography in step C; Doppler-based coronary flow velocity reserve in the left anterior descending coronary artery in step D; and ECG-based heart rate reserve in non-imaging step E. These five biomarkers converge, conceptually and methodologically, in the ABCDE protocol allowing comprehensive risk stratification of the vulnerable patient with chronic coronary syndromes. The present document summarizes current practice guidelines recommendations and training requirements and harmonizes the clinical guidelines of the European Society of Cardiology in many diverse cardiac conditions, from chronic coronary syndromes to valvular heart disease. The continuous refinement of imaging technology and the diffusion of ultrasound-contrast agents improve image quality, feasibility, and reader accuracy in assessing wall motion and perfusion, left ventricular volumes, and coronary flow velocity. Carotid imaging detects pre-obstructive atherosclerosis and improves risk prediction similarly to coronary atherosclerosis. The revolutionary impact of artificial intelligence on echocardiographic image acquisition and analysis makes stress echo more operator-independent and objective. Stress echo has unique features of low cost, versatility, and universal availability. It does not need ionizing radiation exposure and has near-zero carbon dioxide emissions. Stress echo is a convenient and sustainable choice for functional testing within and beyond coronary artery disease.

Stress Echo 2030: the new ABCDE protocol defining the future of cardiac imaging

Functional testing with stress echocardiography is based on the detection of regional wall motion abnormality with two-dimensional echocardiography and is embedded in clinical guidelines. Yet, it under-uses the unique versatility of the technique, ideally suited to describe the different functional abnormalities underlying the same wall motion response during stress. Five parameters converge conceptually and methodologically in the state-of-the-art ABCDE protocol, assessing multiple vulnerabilities of the ischemic patient. The five steps of the ABCDE protocol are (1) step A: regional wall motion; (2) step B: B-lines by lung ultrasound assessing extravascular lung water; (3) step C: left ventricular contractile reserve by volumetric two-dimensional echocardiography; (4) step D: coronary flow velocity reserve in mid-distal left anterior descending coronary with pulsed-wave Doppler; and (5) step E: assessment of heart rate reserve with a one-lead electrocardiogram. ABCDE stress echo offers insight into five functional reserves: epicardial flow (A); diastolic (B), contractile (C), coronary microcirculatory (D), and chronotropic reserve (E). The new format is more comprehensive and allows better functional characterization, risk stratification, and personalized tailoring of therapy. ABCDE protocol is an 'ecumenic' and 'omnivorous' functional test, suitable for all stresses and all patients also beyond coronary artery disease. It fits the need for sustainability of the current era in healthcare, since it requires universally available technology, and is low-cost, radiation-free, and nearly carbon-neutral.

Prognostic value of heart rate reserve in patients with suspected coronary artery disease undergoing stress myocardial perfusion imaging

BACKGROUND

Chronotropic incompetence is common in patients with cardiovascular disease and is associated with increased risk of adverse events. We assessed the incremental prognostic value of heart rate reserve (HRR) over stress myocardial perfusion single-photon emission computed tomography (MPS) findings in patients with suspected coronary artery disease (CAD).

METHODS

We studied 866 patients with suspected CAD undergoing exercise stress-MPS as part of their diagnostic program. The primary study endpoint was all-cause mortality. All patients were followed for at least 5 years. HRR was calculated as the difference between peak exercise and resting HR, divided by the difference of age-predicted maximal and resting HR and expressed as percentage.

RESULTS

During 7 years follow-up, 61 deaths occurred, with a 7% cumulative event rate. Patients experiencing death were older (P < .001), and had a higher prevalence of male gender (P < .001) and diabetes (P < .05). Patients with event also had lower values of HRR (65% ± 27% vs 73% ± 18%, P < .0001) and higher prevalence of stress-induced myocardial ischemia (25% vs 8%, P < .0001). Male gender, HRR and stress-induced ischemia were independent predictors of all-cause mortality (all P < .01). HRR improved the prognostic power of a model including clinical data and MPS findings, increasing the global χ2 from 66 to 82 (P < .005).

CONCLUSIONS

Chronotropic incompetence has independent and incremental prognostic value in predicting all-cause mortality in patients with suspected CAD undergoing exercise stress-MPS. Hence, the evaluation of HRR may further improve patients' risk stratification.

Reduced coronary flow velocity reserve and blunted heart rate reserve identify a higher risk group in patients with chest pain and negative emergency department evaluation

To estimate the prognostic value of stress echo (SE) with the assessment of coronary flow velocity reserve (CFVR) and heart rate reserve (HRR) in patients admitted for chest pain with non-diagnostic EKG, negative troponin, and without inducible regional wall motion abnormalities (RWMA). 658 patients (age 67 ± 12 years) admitted to our Emergency Department with chest pain, non-diagnostic EKG, and negative serial troponin underwent dipyridamole (0.84 mg/kg in 6') SE with simultaneous assessment of RWMA, CFVR in the left anterior descending artery, and HRR as peak/rest heart rate. The outcome measure was all-cause mortality. Of the 658 patients initially enrolled, 20 (3%) showed RWMA during SE and were referred to ischemia-driven revascularization. In the remaining 638, CFVR was abnormal (≤ 2.0) in 148 patients (23%). HRR was abnormal (≤ 1.22 in patients in sinus rhythm, or ≤ 1.17 in patients with permanent atrial fibrillation) in 196 patients (31%). During a follow-up of 7.3 ± 4.3 years, 151 (24%) patients died. Survival at 8 years was 93% in patients with normal CFVR and HRR, 76% in patients with abnormal CFVR only, 73% in patients with abnormal HRR only, and 38% in those with abnormal CFVR and HRR (p < 0.0001). At multivariable analysis, abnormal CFVR (HR 1.49, 95% CI 1.05-2.10, p = 0.02) and abnormal HRR (HR 2.01, 95% CI 1.43-2.84, p < 0.0001) were independent predictors of survival. In admitted patients with non-ischemic EKG, negative serial troponin, and without RWMA during dipyridamole SE, a reduced CFVR and blunted HRR independently identify a subset with worse survival in the long term. Upper panel: Color and pulsed-wave Doppler with the electrocardiographic lead tracing of Four different response patterns (from left to right): normal CFVR and HRR; normal CFVR, abnormal HRR; abnormal CFVR, normal HRR; abnormal CFVR and HRR. Lower panel: The annualized death rate for each of the four groups with negative SE for RWMA and stratified according to the presence of CFVR and HRR: none, one, or two abnormalities.

Vasodilator Strain Stress Echocardiography in Suspected Coronary Microvascular Angina

Background: In patients with Ischemia and non-obstructive coronary artery stenosis (INOCA) wall motion is rarely abnormal during stress echocardiography (SE). Our aim was to determine if patients with INOCA and reduced coronary flow velocity reserve (CVFR) have altered cardiac mechanics using two-dimensional speckle-tracking echocardiography (2DSTE) during SE. Methods: In a prospective, multicenter, international study, we recruited 135 patients with INOCA. Overall, we performed high dose (0.84 mg/kg) dipyridamole SE with combined assessment of CVFR and 2DSTE. The population was divided in patients with normal CVFR (>2, group 1, n = 95) and abnormal CVFR (≤2, group 2, n = 35). Clinical and 2DSTE parameters were compared between groups. Results: Feasibility was high for CFVR (98%) and 2DSTE (97%). A total of 130 patients (mean age 63 ± 12 years, 67 women) had complete flow and strain data. The two groups showed similar 2DSTE values at rest. At peak SE, Group 1 patients showed lower global longitudinal strain (p < 0.007), higher mechanical dispersion (p < 0.0005), lower endocardial (p < 0.001), and epicardial (p < 0.0002) layer specific strain. Conclusions: In patients with INOCA, vasodilator SE with simultaneous assessment of CFVR and strain is highly feasible. Coronary microvascular dysfunction is accompanied by an impairment of global and layer-specific deformation indices during stress.

Insights Into Myocardial Oxygenation and Cardiovascular Magnetic Resonance Tissue Biomarkers in Heart Failure With Preserved Ejection Fraction

BACKGROUND

The pathophysiology of heart failure with preserved ejection fraction is not well understood, but evidence strongly suggests involvement of microvascular dysfunction. We studied the myocardial oxygenation reserve as a direct marker of coronary vascular function and its relation to myocardial deformation and tissue characteristics by cardiovascular magnetic resonance (CMR).

METHODS

In a dual-center case-control study, patients with heart failure and preserved ejection fraction (>50%) and healthy controls older than 50 years underwent quantitative CMR for ventricular volumes and functional assessment with feature tracking, as well as tissue characterization (T1, T2, extracellular volume). Coronary vascular function was measured by oxygenation-sensitive (OS)-CMR of the myocardial oxygenation response to a vasoactive breathing maneuver.

RESULTS

Twenty-nine patients completed the CMR exam. Compared with cutoffs derived from 12 control subjects, circumferential peak strain was attenuated in 97% of patients. Native T1 was elevated in 93%, extracellular volume was elevated in 83%. Sixty-six percent of patients revealed either regional or global myocardial edema, defined by an increased myocardial T2. An attenuated global myocardial oxygenation reserve (<4.4%) was observed in 96% of the patients (1.7±3.9% versus 9.1±5.3% in controls, P<0.001). This was correlated with septal wall thickness (r=-0.54, P=0.003), edema (myocardial T2; β=-0.26% oxygenation-sensitive/ms [95% CI, -0.49 to -0.03], P=0.029), and reduced diastolic strain rate (β=1.50% oxygenation-sensitive/s^-1 [95% CI, 0.06-2.90], P=0.042).

CONCLUSIONS

In patients with clinical heart failure with preserved ejection fraction, vascular dysfunction as measured by an attenuated myocardial oxygenation reserve is associated with myocardial edema, a thicker septum, and diastolic dysfunction. A quantitative comprehensive CMR exam including oxygenation-sensitive-CMR allows for comprehensive imaging-based phenotyping of heart failure with preserved ejection fraction.

Reduced Sympathetic Reserve Detectable by Heart Rate Response after Dipyridamole in Anginal Patients with Normal Coronary Arteries

Background. Patients with ischemia and normal coronary arteries (INOCA) may show abnormal cardiac sympathetic function, which could be unmasked as a reduced heart rate reserve (HRR) during dipyridamole stress echocardiography (SE). Objectives. To assess whether HRR during dipyridamole SE predicts outcome. Methods. Dipyridamole SE was performed in 292 patients with INOCA. HRR was measured as peak/rest heart rate and considered abnormal when ≤1.22 (≤1.17 in presence of permanent atrial fibrillation). All-cause death was the only endpoint. Results. HRR during SE was normal in 183 (63%) and abnormal in 109 patients (37%). During a follow-up of 10.4 ± 5.5 years, 89 patients (30%) died. The 15-year mortality rate was 27% in patients with normal and 54% in those with abnormal HRR (p < 0.0001). In a multivariable analysis, a blunted HRR during SE was an independent predictor of outcome (hazard ratio 1.86, 95% confidence intervals 1.20–2.88; p = 0.006) outperforming inducible ischemia. Conclusions. A blunted HRR during dipyridamole SE predicts a worse survival in INOCA patients, independent of inducible ischemia.

Prognostic value of stress echocardiography assessed by the ABCDE protocol

AIM

The aim of this study was to assess the prognostic value of ABCDE-SE in a prospective, large scale, multicentre, international, effectiveness study. Stress echocardiography (SE) was recently upgraded to the ABCDE protocol: step A, regional wall motion abnormalities; step B, B lines; step C, left ventricular contractile reserve; step D, Doppler-based coronary flow velocity reserve in left anterior descending coronary artery; and step E, electrocardiogram-based heart rate reserve.

METHODS AND RESULTS

From July 2016 to November 2020, we enrolled 3574 all-comers (age 65 ± 11 years, 2070 males, 58%; ejection fraction 60 ± 10%) with known or suspected chronic coronary syndromes referred from 13 certified laboratories. All patients underwent clinically indicated ABCDE-SE. The employed stress modality was exercise (n = 952, with semi-supine bike, n = 887, or treadmill, n = 65 with adenosine for step D) or pharmacological stress (n = 2622, with vasodilator, n = 2151; or dobutamine, n = 471). SE response ranged from score 0 (all steps normal) to score 5 (all steps abnormal). All-cause death was the only endpoint. Rate of abnormal results was 16% for A, 30% for B, 36% for C, 28% for D, and 37% for E steps. During a median follow-up of 21 months (interquartile range: 13-36), 73 deaths occurred. Global X2 was 49.5 considering clinical variables, 50.7 after step A only (P = NS (not significant)) and 80.6 after B-E steps (P < 0.001 vs. step A). Annual mortality rate ranged from 0.4% person-year for score 0 up to 2.7% person-year for score 5.

CONCLUSION

ABCDE-SE allows an effective prediction of survival in patients with chronic coronary syndromes.

Prognostic Value of Heart Rate Reserve during Dipyridamole Stress Echocardiography in Patients With Abnormal Chronotropic Response to Exercise

Heart rate reserve (HRR) during physical or pharmacological stress is a sign of cardiac autonomic function and sympathetic reserve, but it can be reduced during exercise for confounders such as poor motivation, drugs or physical fitness. In this study we sought to assess the prognostic meaning of HRR during dipyridamole stress echocardiography (DSE) in patients with abnormal chronotropic response to exercise. From 2004 to 2019, we prospectively acquired and retrospectively analyzed 379 patients (age 62 ± 11 years; ejection fraction 60 ± 5%) with suspected (n = 243) or known (n = 136) chronic coronary syndromes, referred to DSE for chronotropic incompetence during upright bicycle exercise-electrocardiography test defined as HRR used [(peak HR - rest HR) / (220 - age) - rest HR] ≤80% in patients off and ≤62% in patients on beta-blockers. All patients were in sinus rhythm and underwent DSE (0.84 mg/kg) within 3 months of exercise testing. During DSE, age-independent HRR (peak/rest HR) ≤1.22 was considered abnormal. All patients were followed-up. All-cause death was the only outcome measure. HRR during DSE was normal in 275 (73%) and abnormal in 104 patients (27%). During a follow-up of 9.0 ± 4.2 years, 67 patients (18%) died. The 15-year mortality rate was 23% in patients with normal and 61% in patients with abnormal HRR (p < 0.0001). At multivariable analysis a blunted HRR during DSE was an independent predictor of outcome (hazard ratio 2.01, 95% confidence intervals 1.23-3.29; p = 0.005) with age and diabetes, while neither inducible ischemia nor ongoing beta-blocker therapy were significant predictors. In conclusion, a blunted HRR during DSE predicts a worse survival in patients with chronotropic incompetence during exercise test. HRR during DSE is an appealingly simple biomarker of cardiac autonomic dysfunction independent of imaging, exercise and beta-blocker therapy.

Stress Echo 2030: The Novel ABCDE-(FGLPR) Protocol to Define the Future of Imaging

With stress echo (SE) 2020 study, a new standard of practice in stress imaging was developed and disseminated: the ABCDE protocol for functional testing within and beyond CAD. ABCDE protocol was the fruit of SE 2020, and is the seed of SE 2030, which is articulated in 12 projects: 1-SE in coronary artery disease (SECAD); 2-SE in diastolic heart failure (SEDIA); 3-SE in hypertrophic cardiomyopathy (SEHCA); 4-SE post-chest radiotherapy and chemotherapy (SERA); 5-Artificial intelligence SE evaluation (AI-SEE); 6-Environmental stress echocardiography and air pollution (ESTER); 7-SE in repaired Tetralogy of Fallot (SETOF); 8-SE in post-COVID-19 (SECOV); 9: Recovery by stress echo of conventionally unfit donor good hearts (RESURGE); 10-SE for mitral ischemic regurgitation (SEMIR); 11-SE in valvular heart disease (SEVA); 12-SE for coronary vasospasm (SESPASM). The study aims to recruit in the next 5 years (2021–2025) ≥10,000 patients followed for ≥5 years (up to 2030) from ≥20 quality-controlled laboratories from ≥10 countries. In this COVID-19 era of sustainable health care delivery, SE2030 will provide the evidence to finally recommend SE as the optimal and versatile imaging modality for functional testing anywhere, any time, and in any patient.

Coronary Flow, Left Ventricular Contractile and Heart Rate Reserve in Non-Ischemic Heart Failure

Background: Left ventricular contractile reserve (LVCR), coronary flow velocity reserve (CFVR), and heart rate reserve (HRR) affect outcome in heart failure (HF). They can be simultaneously measured during dipyridamole stress echocardiography (DSE). Aim: To assess the value of comprehensive DSE in patients with non-ischemic HF. Methods: We evaluated 610 patients with HF, no history of coronary artery disease, and no inducible regional wall motion abnormalities: 270 patients with preserved ejection fraction (≥50%), 146 patients with mid-range ejection fraction (40–49%), and 194 patients with reduced ejection fraction (<40%). All underwent DSE (0.84 mg/kg in 6′) in 7 accredited laboratories. We measured LVCR (abnormal value ≤ 1.1), CFVR in left anterior descending artery (abnormal value: ≤2.0), and HRR (peak/rest heart rate; abnormal value: ≤1.22). All patients were followed up. Results: Abnormal CFVR, LVCR, and HRR occurred in 29%, 45%, and 47% of patients, respectively (p < 0.001). After a median follow-up time of 20 months (interquartile range: 12–32 months), 113 hard events occurred in 105 patients with 41 deaths, 8 myocardial infarctions, 61 admissions for acute HF, and 3 strokes. The annual mortality rates were 0.8% in 200 patients with none abnormal criteria, 1.8% in 184 patients with 1 abnormal criterion, 7.1% in 130 patients with 2 abnormal criteria, 7.5% in 96 patients with 3 abnormal criteria. Conclusions: Abnormal LVCR, CFVR, and HRR were frequent during DSE in non-ischemic HF patients. They target different pathophysiological vulnerabilities (myocardial function, coronary microcirculation, and cardiac autonomic balance) and are useful for outcome prediction.

Hemodynamic Heterogeneity of Reduced Cardiac Reserve Unmasked by Volumetric Exercise Echocardiography

Background: Two-dimensional volumetric exercise stress echocardiography (ESE) provides an integrated view of left ventricular (LV) preload reserve through end-diastolic volume (EDV) and LV contractile reserve (LVCR) through end-systolic volume (ESV) changes. Purpose: To assess the dependence of cardiac reserve upon LVCR, EDV, and heart rate (HR) during ESE. Methods: We prospectively performed semi-supine bicycle or treadmill ESE in 1344 patients (age 59.8 ± 11.4 years; ejection fraction = 63 ± 8%) referred for known or suspected coronary artery disease. All patients had negative ESE by wall motion criteria. EDV and ESV were measured by biplane Simpson rule with 2-dimensional echocardiography. Cardiac index reserve was identified by peak-rest value. LVCR was the stress-rest ratio of force (systolic blood pressure by cuff sphygmomanometer/ESV, abnormal values ≤2.0). Preload reserve was defined by an increase in EDV. Cardiac index was calculated as stroke volume index * HR (by EKG). HR reserve (stress/rest ratio) <1.85 identified chronotropic incompetence. Results: Of the 1344 patients, 448 were in the lowest tertile of cardiac index reserve with stress. Of them, 303 (67.6%) achieved HR reserve <1.85; 252 (56.3%) had an abnormal LVCR and 341 (76.1%) a reduction of preload reserve, with 446 patients (99.6%) showing ≥1 abnormality. At binary logistic regression analysis, reduced preload reserve (odds ratio [OR]: 5.610; 95% confidence intervals [CI]: 4.025 to 7.821), chronotropic incompetence (OR: 3.923, 95% CI: 2.915 to 5.279), and abnormal LVCR (OR: 1.579; 95% CI: 1.105 to 2.259) were independently associated with lowest tertile of cardiac index reserve at peak stress. Conclusions: Heart rate assessment and volumetric echocardiography during ESE identify the heterogeneity of hemodynamic phenotypes of impaired chronotropic, preload or LVCR underlying a reduced cardiac reserve.

Prognostic Value of Reduced Heart Rate Reserve during Exercise in Hypertrophic Cardiomyopathy

BACKGROUND

Sympathetic dysfunction can be evaluated by heart rate reserve (HRR) with exercise test.

OBJECTIVES

To determine the value of HRR in predicting outcome of patients with hypertrophic cardiomyopathy (HCM).

METHODS

We enrolled 917 HCM patients (age = 49 ± 15 years, 516 men) assessed with exercise stress echocardiography (ESE) in 11 centres. ESE modality was semi-supine bicycle in 51 patients (6%), upright bicycle in 476 (52%), and treadmill in 390 (42%). During ESE, we assessed left ventricular outflow tract obstruction (LVOTO), stress-induced new regional wall motion abnormalities (RWMA), and HRR (peak/rest heart rate, HR). By selection, all patients completed the follow-up. Mortality was the predetermined outcome measure Results: During ESE, RWMA occurred in 22 patients (2.4%) and LVOTO (≥50 mmHg) in 281 (30.4%). HRR was 1.90 ± 0.40 (lowest quartile ≤ 1.61, highest quartile > 2.13). Higher resting heart rate (odds ratio 1.027, 95% CI: 1.018-1.036, p < 0.001), older age (odds ratio 1.021, 95% CI: 1.009-1.033, p < 0.001), lower exercise tolerance (mets, odds ratio 0.761, 95% CI: 0.708-0.817, p < 0.001) and resting LVOTO (odds ratio 1.504, 95% CI: 1.043-2.170, p = 0.029) predicted a reduced HRR. During a median follow-up of 89 months (interquartile range: 36-145 months), 90 all-cause deaths occurred. At multivariable analysis, lowest quartile HRR (Hazard ratio 2.354, 95% CI 1.116-4.968 p = 0.025) and RWMA (Hazard ratio 3.279, 95% CI 1.441-7.461 p = 0.004) independently predicted death, in addition to age (Hazard ratio 1.064, 95% CI 1.043-1.085 p < 0.001) and maximal wall thickness (Hazard ratio 1.081, 95% CI 1.037-1.128, p < 0.001).

CONCLUSIONS

A blunted HRR during ESE predicts survival independently of RWMA in HCM patients.

Additional prognostic value of heart rate reserve over left ventricular contractile reserve and coronary flow velocity reserve in diabetic patients with negative vasodilator stress echocardiography by regional wall motion criteria

AIMS 

In diabetic patients, a blunted left ventricular contractile reserve (LVCR) and/or a reduced coronary flow velocity reserve (CFVR) identify patients at higher risk in spite of stress echocardiography (SE) negative for ischaemia. Cardiac autonomic dysfunction contributes to risk profile independently of inducible ischaemia and can be assessed with heart rate reserve (HRR). We sought to assess the added prognostic value of HRR to LVCR and CFVR in diabetic patients with non-ischaemic SE.

METHODS AND RESULTS 

Six-hundred and thirty-six diabetic patients (age 68 ± 9 years, 396 men, ejection fraction 58 ± 10%) with sinus rhythm on resting electrocardiogram underwent dipyridamole SE in a two-centre prospective study with assessment of wall motion, force-based LVCR (stress/rest ratio, normal value > 1.1), CFVR of the left anterior descending coronary artery (stress/rest ratio, normal value >2.0), and HRR (stress/rest ratio, normal value >1.22). All-cause death was the only considered endpoint. During a median follow-up of 39 months, 94 (15%) patients died. Independent predictors of death were abnormal CFVR [hazard ratio (HR) 1.59, 95% confidence interval (CI) 1.0-2.52, P = 0.05], reduced LVCR (HR 1.76, 95% CI 1.15-2.69, P = 0.009), and blunted HRR (HR 1.92, 95% CI 1.24-2.96, P = 0.003). Eight-year death rate was 9% for patients with triple negativity (n = 252; 40%), 18% for those with single positivity (n = 216; 34%), 36% with double positivity (n = 124; 19%), and 64% for triple positivity (n = 44; 7%) (P < 0.0001).

CONCLUSION 

Diabetic patients with dipyridamole SE negative for ischaemia still may have a significant risk in presence of an abnormal LVCR and/or CFVR and/or HRR, which assess the underlying myocardial, microvascular, and cardiac autonomic dysfunction.

CLINICAL TRIALS

Gov Identifier NCT 030.49995.

Feasibility and functional correlates of left atrial volume changes during stress echocardiography in chronic coronary syndromes

An enlarged left atrial volume index (LAVI) at rest mirrors increased LA pressure and/or impairment of LA function. A cardiovascular stress may acutely modify left atrial volume (LAV) within minutes. Aim of this study was to assess the feasibility and functional correlates of LAV-stress echocardiography (SE) Out of 514 subjects referred to 10 quality-controlled labs, LAV-SE was completed in 490 (359 male, age 67 ± 12 years) with suspected or known chronic coronary syndromes (n = 462) or asymptomatic controls (n = 28). The utilized stress was exercise in 177, vasodilator in 167, dobutamine in 146. LAV was measured with the biplane disk summation method. SE was performed with the ABCDE protocol. The intra-observer and inter-observer LAV variability were 5% and 8%, respectively. ∆-LAVI changes (stress-rest) were negatively correlated with resting LAVI (r = - 0.271, p < 0.001) and heart rate reserve (r = -.239, p < 0.001). LAV-dilators were defined as those with stress-rest increase ≥ 6.8 ml/m², a cutoff derived from a calculated reference change value above the biological, analytical and observer variability of LAVI. LAV dilation occurred in 56 patients (11%), more frequently with exercise (16%) and dipyridamole (13%) compared to dobutamine (4%, p < 0.01). At multivariable logistic regression analysis, B-lines ≥ 2 (OR: 2.586, 95% CI = 1.1293-5.169, p = 0.007) and abnormal contractile reserve (OR: 2.207, 95% CI = 1.111-4.386, p = 0.024) were associated with LAV dilation. In conclusion, LAV-SE is feasible with high success rate and low variability in patients with chronic coronary syndromes. LAV dilation is more likely with reduced left ventricular contractile reserve and pulmonary congestion.

Sustainability and Versatility of the ABCDE Protocol for Stress Echocardiography

For the past 40 years, the methodology for stress echocardiography (SE) has remained basically unchanged. It is based on two-dimensional, black and white imaging, and is used to detect regional wall motion abnormalities (RWMA) in patients with known or suspected coronary artery disease (CAD). In the last five years much has changed and RWMA is not enough on its own to stratify patient risk and dictate therapy. Patients arriving at SE labs often have comorbidities and are undergoing full anti-ischemic therapy. The SE positivity rate based on RWMA fell from 70% in the eighties to 10% in the last decade. The understanding of CAD pathophysiology has shifted from a regional hydraulic disease to a systemic biologic disease. The conventional view of CAD encouraged the use of coronary anatomic imaging for diagnosis and the oculo-stenotic reflex for the deployment of therapy. This has led to a clinical oversimplification that ignores the lessons of pathophysiology and epidemiology, and in fact, CAD is not synonymous with ischemic heart disease. Patients with CAD may also have other vulnerabilities such as coronary plaque (step A of ABCDE-SE), alveolar-capillary membrane and pulmonary congestion (step B), preload and contractile reserve (step C), coronary microcirculation (step D) and cardiac autonomic balance (step E). The SE methodology based on two-dimensional echocardiography is now integrated with lung ultrasound (step B for B-lines), volumetric echocardiography (step C), color- and pulsed-wave Doppler (step D) and non-imaging electrocardiogram-based heart rate assessment (step E). In addition, qualitative assessment based on the naked eye has now become more quantitative, has been improved by contrast and based on cardiac strain and artificial intelligence. ABCDE-SE is now ready for large scale multicenter testing in the SE2030 study.

Lung Ultrasound and Pulmonary Congestion During Stress Echocardiography

OBJECTIVES

The purpose of this study was to assess the functional and prognostic correlates of B-lines during stress echocardiography (SE).

BACKGROUND

B-profile detected by lung ultrasound (LUS) is a sign of pulmonary congestion during SE.

METHODS

The authors prospectively performed transthoracic echocardiography (TTE) and LUS in 2,145 patients referred for exercise (n = 1,012), vasodilator (n = 1,054), or dobutamine (n = 79) SE in 11 certified centers. B-lines were evaluated in a 4-site simplified scan (each site scored from 0: A-lines to 10: white lung for coalescing B-lines). During stress the following were also analyzed: stress-induced new regional wall motion abnormalities in 2 contiguous segments; reduced left ventricular contractile reserve (peak/rest based on force, ≤2.0 for exercise and dobutamine, ≤1.1 for vasodilators); and abnormal coronary flow velocity reserve ≤2.0, assessed by pulsed-wave Doppler sampling in left anterior descending coronary artery and abnormal heart rate reserve (peak/rest heart rate) ≤1.80 for exercise and dobutamine (≤1.22 for vasodilators). All patients completed follow-up.

RESULTS

According to B-lines at peak stress patients were divided into 4 different groups: group I, absence of stress B-lines (score: 0 to 1; n = 1,389; 64.7%); group II, mild B-lines (score: 2 to 4; n = 428; 20%); group III, moderate B-lines (score: 5 to 9; n = 209; 9.7%) and group IV, severe B-lines (score: ≥10; n = 119; 5.4%). During median follow-up of 15.2 months (interquartile range: 12 to 20 months) there were 38 deaths and 28 nonfatal myocardial infarctions in 64 patients. At multivariable analysis, severe stress B-lines (hazard ratio [HR]: 3.544; 95% confidence interval [CI]: 1.466 to 8.687; p = 0.006), abnormal heart rate reserve (HR: 2.276; 95% CI: 1.215 to 4.262; p = 0.010), abnormal coronary flow velocity reserve (HR: 2.178; 95% CI: 1.059 to 4.479; p = 0.034), and age (HR: 1.031; 95% CI: 1.002 to 1.062; p = 0.037) were independent predictors of death and nonfatal myocardial infarction.

CONCLUSIONS

Severe stress B-lines predict death and nonfatal myocardial infarction. (Stress Echo 2020-The International Stress Echo Study [SE2020]; NCT03049995).

Prognostic Value of Heart Rate Reserve in Patients with Permanent Atrial Fibrillation during Dipyridamole Stress Echocardiography

In patients in sinus rhythm, a blunted heart rate reserve (HRR) during dipyridamole stress echocardiography (SE) is a prognostically unfavorable sign of cardiac autonomic dysfunction. In this study we sought to assess the prognostic meaning of HRR in patients with permanent atrial fibrillation (AF). The study population was made by 301 patients (176 men, age 73 ± 8 years) with suspected (n = 200) or known (n = 101) coronary artery disease and permanent AF who underwent high-dose dipyridamole SE. HRR was calculated on an average of 5 consecutive beats as the peak/rest ratio of HR from 12-lead EKG. During a median follow-up time of 77 months (first quartile 44, third quartile 115 months), 111 (37%) patients died. Receiver operating characteristics analysis identified HRR ≤1.17 as the best predictor of mortality. At multivariable analysis, HRR ≤1.17 (HR 1.75, 95% CI 1.17 to 2.62; p = 0.006) independently predicted mortality together with age (HR 1.09, 95% CI 1.06 to 1.13; p <0.0001), rest wall motion score index (HR 1.69, 95% CI 1.01 to 2.83; p = 0.04), and systemic hypertension (HR 1.76, 95% CI 1.06 to 3.00; p = 0.04). The annual mortality was 5.1% in the overall population, 7.0% in the 140 (46%) patients with abnormal HRR and 3.5% in the 161 (54%) patients with normal HRR. The 8-year mortality was 48% in patients with abnormal HRR and 18% in those with normal HRR (p <0.0001). In conclusion, patients with suspected or known coronary artery disease with permanent AF with a blunted HRR have an increased mortality. HRR outweighs inducible ischemia for prediction of survival. The assessment of HRR should become an integral part of dipyridamole SE reading also in AF.

Prognostic value of heart rate reserve is additive to coronary flow velocity reserve during dipyridamole stress echocardiography

BACKGROUND

During dipyridamole stress echocardiography (SE), a blunted heart rate reserve (HRR) is a prognostically unfavourable sign of cardiac autonomic dysfunction.

AIM

To assess the prognostic meaning of HRR and coronary flow velocity reserve (CFVR).

METHODS

The study group comprised 2149 patients (1236 men; mean age 66±12 years) with suspected (n=1280) or known (n=869) coronary artery disease and without inducible regional wall motion abnormalities (RWMA) during dipyridamole SE (0.84mg/kg in 6min). We assessed CFVR of the left anterior descending artery with pulsed-wave Doppler as the ratio between hyperaemic peak and basal peak diastolic flow velocities (abnormal value≤2.0). HRR was calculated as the peak/resting ratio of heart rate from a 12-lead electrocardiogram (abnormal value≤1.22). All patients were followed up.

RESULTS

CFVR and HRR were abnormal in 520 (24%) and 670 (31%) patients, respectively. There was a positive linear correlation between CFVR and HRR (r=0.30; P<0.0001). During a median follow-up of 22 months (1st quartile 12 months, 3rd quartile 35 months), 75 (6%) patients died. The annual mortality was 1.6% in the overall population, 0.5% in the 1224 (57%) patients with normal CFVR and HRR, 1.7% in the 405 (19%) patients with abnormal HRR only, 3.6% in the 255 (12%) patients with abnormal CFVR only, and 6.2% in the 265 (12%) patients with abnormal CFVR and HRR.

CONCLUSIONS

HRR is weakly related to CFVR, and a blunted HRR usefully complements RWMA and CFVR for prediction of outcome with dipyridamole SE. The patient without inducible RWMA is still at intermediate risk, but the risk is low with concomitant preserved CFVR, and very low with concomitant normal HRR.

Heart rate reserve during dipyridamole stress test applied to potential heart donors in brain death

BACKGROUND

A blunted heart rate reserve (HRR) during dipyridamole stress echocardiography (DSE) is a prognostically unfavorable sign of cardiac autonomic dysfunction. Short-term adjustments of heart rate (HR) are thought to rise from changes in neural input to the heart. DSE is applied in potential heart donors to rule out underlying coronary artery disease and left ventricular dysfunction. The aim of this study is to assess HRR during DSE in brain death.

METHODS

We enrolled two groups: group 1 (N.=49, 22 men, 54.6±8.8 years) with patients in brain death enrolled in the nationwide marginal donor heart recruiting program; group 2 (N.=49, 18 men, 66.4±12.0 years) referred to DSE for suspected or known coronary artery disease. All underwent DSE (0.84 mg/kg in 6') by quality-controlled readers certified via web-based training (1487/CE Lazio-1). We assessed left ventricular contractile reserve (LVCR) as stress/rest ratio of force (systolic blood pressure/end-systolic volume). HRR was calculated as the peak/rest HR ratio from 12-lead EKG.

RESULTS

The two study groups were similar for prevalence of inducible ischemia (4/49 vs. 9/49, P=NS). Group 1 showed higher resting HR (group 1: 88.1±15.5 bpm vs. group 2: 66.5±11.5 bpm, P<0.01) and similar peak HR (group 1: 94.7±15.3 bpm vs. group 2: 89.5±19.3 bpm, P=0.144), with blunted HRR (group 1: 1.08±0.10 bpm vs. group 2: 1.36±0.31 bpm, P<0.01). HRR was unrelated to LVCR.

CONCLUSIONS

HRR is almost abolished and unrelated to LVCR in brain-dead patients during DSE. The modulation of neural input to the heart is essential to determine HRR, and plays no significant role in determining the inotropic response during DSE.