The declining frequency of inducible myocardial ischemia during stress echocardiography over 27 consecutive years (1983-2009)

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.

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.

Temporal trends in test utilization and prevalence of ischaemia with positron emission tomography myocardial perfusion imaging

AIMS

To examine whether test utilization and prevalence of ischemia with positron emission tomography (PET) myocardial perfusion imaging (MPI) follow the previously described trends with single photon computed tomography (SPECT).

METHODS AND RESULTS

MPI studies performed between January 2003 and December 2017 were identified. Number of PET and SPECT MPI studies performed per year was determined. Trends in the proportion of studies showing any ischaemia (>0%) with both modalities were compared before and after adjusting for baseline differences in patient characteristics using propensity scores. Interaction between imaging modality and year of testing was examined using modified Poisson regression. A total of 156 244 MPI studies were performed (30% PET and 70% SPECT). Between 2003 and 2017, the number of PET studies increased from 18 to 61 studies/1000 patient encounters, while SPECT volumes declined from 169 to 34/1000 patient encounters (P < 0.001 for within-group comparisons). The prevalence of any ischaemia in SPECT-tested patients declined from 53.9% to 28.3% between 2003 and 2017, whereas ischaemia prevalence in PET-tested patients declined from 57.2% to 38.2% (P < 0.001 for within-modality comparisons), with more PET studies showing ischaemia compared to SPECT [relative risk (RR) 1.44, 95% confidence interval (CI) 1.42-1.47; P < 0.001]. After propensity score matching of 26 066 patients tested with SPECT with 26 066 patients tested with PET, the between-modality difference in ischaemia prevalence was significantly attenuated, with a slightly higher overall likelihood of detecting ischaemia with PET compared to SPECT (RR 1.08, 95% CI 1.05-1.11; P < 0.001).

CONCLUSIONS

Utilization of PET MPI at a large-volume referral centre increased significantly between 2003 and 2017. Despite a significant decrease in the prevalence of ischaemia with SPECT and PET during the same period, the decline was less with PET, perhaps related to baseline risk of tested patients.

Apparent Declining Prognostic Value of a Negative Stress Echocardiography Based on Regional Wall Motion Abnormalities in Patients With Normal Resting Left Ventricular Function Due to the Changing Referral Profile of the Population Under Study

Background Cardiology guidelines identify the low-risk response during stress echocardiography as the absence of regional wall motion abnormalities. Methods From 1983 to 2016, we enrolled 5817 patients (age 63±12 years; 2830 males) with suspected coronary artery disease, normal regional, and global left ventricular function at rest and during stress (exercise in 692, dipyridamole in 4291, and dobutamine in 834). Based on timing of enrollment, 4 groups were identified in chronological order of recruitment: years 1983 to 1989, group 1 (n=211); years 1990 to 1999, group 2 (n=1491); years 2000 to 2009, group 3 (n=3285); and years 2010 to 2016, group 4 (n=830). Results There were 240 (4%) events (119 deaths and 121 infarctions) in the follow-up. At 1-year follow-up, the event rate was 0.5% (95% CI, 0.05-0.95), 1.5% (95% CI, -1.18 to 1.82), 1.9% (95% CI, 1.63-2.17), and 1.7% (95% CI, 1.01-2.39; χ², 9.0; P=0.03) in groups 1 to 4, respectively. At multivariable Cox analysis, independent predictors of future events were age (hazard ratio (HR), 1.05; 95% CI, 1.04-1.07; P<0.0001), male sex (HR, 1.57; 95% CI, 1.20-2.04; P=0.001), diabetes mellitus (HR, 1.78; 95% CI, 1.34-2.37; P<0.0001), smoking habit (HR, 1.40; 95% CI, 1.05-1.85; P=0.02), and ongoing anti-ischemic therapy (HR, 1.50; 95% CI, 1.15-1.97; P=0.003) Conclusions Over the past 3 decades, we observed a progressive decline in the prognostic value of a negative test based on regional wall motion abnormalities, likely reflecting both an increase in risk in patients, as well as a potential decrease in test performance due to concomitant anti-ischemic therapy.

Imaging functional stress test for stable chest pain symptoms in patients at low pretest probability of coronary artery disease: Current practice and long-term outcome

BACKGROUND

Stress testing in patients with low pretest probability (PTP) of coronary artery disease (CAD) has become an increasing practice, potentially leading to underestimation of its true clinical value. Our aim was to describe the current use of most employed imaging functional tests and their prognostic value.

METHODS AND RESULTS

We selected patients with low PTP of CAD (CAD consortium clinical score < 15%) who underwent exercise or dipyridamole stress echocardiography or single photon emission computed tomography for suspected angina. Main exclusions were age < 45, known CAD, and abnormal rest wall motion. Of the 2279 subjects undergoing stress test, 883 (39%) had low PTP, and 91 (10.3%) had a positive test for ischemia. After a median follow-up of 5.8 years, 36 patients had events (21 died, 14 had nonfatal myocardial infarction). The percentage of events in the abnormal and normal stress test groups were similar (5 [5.5%] vs 31 [3.9%], P = ns), as the annualized event rate (0.87% vs 0.62%, P = ns). Age was the only variable associated with outcome in the regression analysis (hazard ratio 1.072, 95% CI 1.034-1.113, P < 0.001). An abnormal result was not associated with worse outcome in each of the subgroups of functional tests.

CONCLUSIONS

In our geographical area, a considerable proportion of patients undergoing imaging functional tests for stable chest pain have a low estimated PTP of CAD. Of these, 1 in 10 resulted positive for inducible ischemia. However, none of the most common imaging functional tests, single photon emission computed tomography (SPECT), and stress echocardiography offer prognostic information in these patients.

Drop-off in positivity rate of stress echocardiography based on regional wall motion abnormalities over the last three decades

Previous studies have suggested a decline in positivity of stress cardiac imaging based on regional wall motion abnormalities (RWMA). To assess the rate of RWMA positivity of stress echocardiography (SE) over 3 decades in the same primary care SE lab. We retrospectively assessed the rate of SE positivity in 7626 SE tests (dipyridamole in 5053, dobutamine in 2496, exercise in 77) in consecutive patients with known or suspected coronary artery disease and /or heart failure who performed SE in a primary care referral center from April 1991 to May 2018. Starting April 2005, SE based on RWMA was complemented by assessment of coronary flow velocity reserve (CFVR) of the left anterior descending coronary artery. Starting October 2016, we added left ventricular contractile reserve (LVCR). Starting October 2016, we also added B-lines by lung ultrasound. There was a progressive decline over time in the rate of SE positivity based on RWMA from 24% (1991-1999) to 10% (2000-2009) down to 4% (2010-2018) (p < 0.0001). Positivity rate was 29% with CFVR, 16% with LVCR, and 12% with B-lines. Over three decades, we observed a dramatic decline in SE positivity rate based on classical RWMA. In the last decade, the positivity rate rose sharply thanks to the stepwise introduction of CFVR, LVCR and B-lines as additional positivity criteria in integrated quadruple SE.

The new clinical standard of integrated quadruple stress echocardiography with ABCD protocol

BACKGROUND

The detection of regional wall motion abnormalities is the cornerstone of stress echocardiography. Today, stress echo shows increasing trends of utilization due to growing concerns for radiation risk, higher cost and stronger environmental impact of competing techniques. However, it has also limitations: underused ability to identify factors of clinical vulnerability outside coronary artery stenosis; operator-dependence; low positivity rate in contemporary populations; intermediate risk associated with a negative test; limited value of wall motion beyond coronary artery disease. Nevertheless, stress echo has potential to adapt to a changing environment and overcome its current limitations.

INTEGRATED-QUADRUPLE STRESS-ECHO

Four parameters now converge conceptually, logistically, and methodologically in the Integrated Quadruple (IQ)-stress echo. They are: 1- regional wall motion abnormalities; 2-B-lines measured by lung ultrasound; 3-left ventricular contractile reserve assessed as the stress/rest ratio of force (systolic arterial pressure by cuff sphygmomanometer/end-systolic volume from 2D); 4- coronary flow velocity reserve on left anterior descending coronary artery (with color-Doppler guided pulsed wave Doppler). IQ-Stress echo allows a synoptic functional assessment of epicardial coronary artery stenosis (wall motion), lung water (B-lines), myocardial function (left ventricular contractile reserve) and coronary small vessels (coronary flow velocity reserve in mid or distal left anterior descending artery). In "ABCD" protocol, A stands for Asynergy (ischemic vs non-ischemic heart); B for B-lines (wet vs dry lung); C for Contractile reserve (weak vs strong heart); D for Doppler flowmetry (warm vs cold heart, since the hyperemic blood flow increases the local temperature of the myocardium). From the technical (acquisition/analysis) viewpoint and required training, B-lines are the kindergarten, left ventricular contractile reserve the primary (for acquisition) and secondary (for analysis) school, wall motion the university, and coronary flow velocity reserve the PhD program of stress echo.

CONCLUSION

Stress echo is changing. As an old landline telephone with only one function, yesterday stress echo used one sign (regional wall motion abnormalities) for one patient with coronary artery disease. As a versatile smart-phone with multiple applications, stress echo today uses many signs for different pathophysiological and clinical targets. Large scale effectiveness studies are now in progress in the Stress Echo2020 project with the omnivorous "ABCD" protocol.

Integrated quadruple stress echocardiography

Stress echocardiography (SE) is an established diagnostic technique. For 40 years, the cornerstone of the technique has been the detection of regional wall motion abnormalities (RWMA), due to the underlying physiologically-relevant epicardial coronary artery stenosis. In the last decade, three new parameters (more objective than RWMA) have shown the potential to integrate and complement RWMA: 1) B-lines, also known as ultrasound lung comets, as a marker of extravascular lung water, measured using lung ultrasound with the 4-site simplified scan symmetrically of the antero-lateral thorax on the third intercostal space, from mid-axillary to anterior axillary and mid-clavicular line; 2) left ventricular contractile reserve (LVCR), assessed as the peak stress/rest ratio of left ventricular force, also known as elastance (systolic arterial pressure by cuff sphygmomanometer/end-systolic volume from 2D echocardiography); 3) coronary flow velocity reserve (CFVR) on left anterior descending coronary artery, calculated as peak stress/rest ratio of diastolic peak flow velocity assessed using pulsed-wave Doppler. The 4 parameters (RWMA, B-lines, LVCR and CFVR) now converge conceptually, logistically, and methodologically in the Integrated Quadruple (IQ)-SE. IQ-SE optimizes the versatility of SE to include in a one-stop shop the core "ABCD" (asynergy+B-lines+contractile reserve+Doppler flowmetry) protocol. It allows a synoptic assessment of parameters mirroring the epicardial artery stenosis (RWMA), interstitial lung water (B-lines), myocardial function (LVCR) and small coronary vessels (CFVR). Each variable has a clear clinical correlate, different and complementary to all others: RWMA identify an ischemic vs. non-ischemic heart; B-lines a wet vs. dry lung; LVCR a strong vs. weak heart; CFVR a warm vs. cold heart. IQ-SE is highly feasible, with minimal increase in the imaging and analysis time, and obvious diagnostic and prognostic impact also beyond coronary artery disease - especially in heart failure. Large scale effectiveness studies with IQ-SE are now under way with the Stress Echo 2020 Study, and will provide the necessary evidence base prior to large scale acceptance of the technique.

Equivocal tests after contrast stress-echocardiography compared with invasive coronary angiography or with CT angiography: CT calcium score in mildly positive tests may spare unnecessary coronary angiograms

Background

Imaging stress tests are not ideally accurate to predict anatomically obstructive CAD, leading to a non-trivial rate of unnecessary iCA. This may depend on the threshold used to indicate iCA, and maybe CTA or, one step earlier, CT calcium score could spare most unnecessary iCA in only mildly positive cSE. We assessed the diagnostic accuracy of contrast stress-echocardiography (cSE) in comparison with invasive coronary angiography (iCA), and CT angiography (CTA) only in case of equivocal tests, to find hints helping reduce falsely positive cSE in the suspicion of coronary artery disease (CAD).

Methods

Patients who were indicated cSE for suspected CAD between 2012 and 2016, who also underwent iCA were selected and diagnostic results compared. A second group, specifically with equivocal cSE who underwent CTA was also analyzed.

Results

137 subjects with equivocal cSE and CTA and 314 with cSE (any result) and iCA were selected. In the CTA-equivocal cSE group, an Agatston score < 105 and a coronary flow reserve (CFR-LAD) <1.7 had very high negative predictive value (99%, 92% respectively) to exclude obstructive CAD. The Agatston score was the most significant incremental predictor of CAD beyond clinical variables (chi square 31 to 47, p < 0.001). In the iCA group a more-than-mild reversible wall motion abnormality (WMA) demonstrated high positive predictive value for CAD (89%), while CFR-LAD appeared less useful. More-than-mild reversible WMA was the most significant predictor of CAD beyond clinical variables (chi square 37.5 to 56, p < 0.001).

Conclusions

Our data suggest iCA should be indicated only for more-than-mild reversible WMA at cSE, due to the very high positive predictive value for CAD of this finding, while mildly positive tests should be shifted to non-invasive CT, with CTA performed only for coronary calcium Agatston score > 100, since lower scores demonstrated very high negative predictive value for CAD, not justifying proceeding to CTA and even less to iCA.

12-year Temporal Trend in Referral Pattern and Test Results of Stress Echocardiography in a Tertiary Care Referral Center with Moderate Volume Activities and Cath-lab Facility

Background

Data on stress echocardiography (SE) time-related changes in referral patterns and diagnostic yield for detection of inducible ischemia could enhance Echo Lab quality benchmarks and performance measures.

Aim

This study aims to evaluate temporal trends in SE test results among ambulatory patients with suspected or known coronary artery disease (CAD) in a tertiary care referral center with moderate (>100/year) volume SE activities and Cath-Lab facility.

Methods

From January 2004 to December 2015, 1954 patients (mean age 62 ± 12 years, 42% women, 27% with known CAD) underwent SE (1673 exercise SE, 86%, 246 pharmacological SE, 12%, 35 pacing SE, 2%). Time was grouped into three 4 year periods, where clinical data and test results were evaluated.

Results

Our series comprised low-to-intermediate pretest probability of CAD throughout the observation period (overall pretest probability of CAD 19% ± 15%). A progressive decline over time in the rate of pharmacological SE instead of a dramatic increment of exercise SE (79%-96%, P < 0.0001) was noted. The use of beta-blockers increased (from 43% to 66%, P < 0.0001), while the use of nitrates decreased (from 11% to 4%, P < 0.0001) over time. We noted a very uncommon occurrence of abnormal test results with a further decrease in the last period (from 11% to 3%, P < 0.0001).

Conclusions

We observed, over a 12-year period, a progressive decrease in the frequency of inducible myocardial ischemia among patients with known or suspected CADe referred to our Echo Lab for SE with Cath-Lab facility, and this trend was parallel to changes in SE referral practice. These findings are particularly relevant if we consider the practical implications on diagnostic SE accuracy and risk assessment.

Simple six-item clinical score improves risk prediction capability of stress echocardiography

Objectives

To assess the value of a simple score integrating non-ischaemia-related variables in expanding the wall motion abnormalities risk power during stress echocardiography (SE).

Methods

Study includes 14 279 patients who underwent SE for evaluation of coronary artery disease. All-cause death was the end point. Patients were randomly divided into the modelling and validation group of equal size. In the modelling group, multivariate analysis was conducted using clinical, rest and SE data, and a score was obtained from the number of non-ischaemia-related independent prognostic predictors. The score prognostic capability was compared in both groups.

Results

During a median follow-up of 31 months, 1230 patients died: 622 (9%) in the modelling and 608 (9%) in the validation group (p=0.68). Independent predictors of mortality were ischaemia at SE (HR 1.77, 95% CI 1.49 to 2.12; p<0.0001) and six other parameters: age>65 years, wall motion at rest, diabetes, left bundle branch block, anti-ischaemic therapy and male sex. Risk score resulted prognostically effective in the modelling and validation groups, both with and without inducible ischaemia subset. When risk score was included in the multivariate analysis, besides ischaemia at SE it was the only independent predictor of mortality in the modelling (HR 1.70, 95% CI 1.60 to 1.82; p<0.0001), in the validation (HR 1.77, 95% CI 1.65 to 1.90; p<0.0001) and in the overall group (HR 1.73, 95% CI 1.66 to 1.82; p<0.0001).

Conclusions

Simple clinical variables may be able to optimise SE risk stratification.