Serious and potentially life threatening complications of cardiac stress testing: Physiological mechanisms and management strategies

Diagnostic accuracy of diastolic pressure ratio using a pressure microcatheter for intracoronary physiological assessment

Recently, instantaneous wave-free ratio (iFR) has emerged as an alternative to the fractional flow reserve (FFR) for intracoronary physiological assessment. Although all diastolic resting indices are reportedly identical to the iFR, limited data exist on diastolic pressure ratio (dPR) measured using a microcatheter (dPRmicro). This study aimed to evaluate the diagnostic accuracy of dPRmicro compared to FFR measured using a microcatheter (FFRmicro) in real-world practice for intracoronary physiological assessment. This was a single-center, retrospective, observational study. We identified 103 consecutive suspected angina pectoris patients (107 lesions) who underwent dPRmicro and FFRmicro measurement using the Navvus® catheter at Takasaki Heart Hospital from March 2019 to June 2019. A total of 103 lesions in 103 patients were finally included in the study. The mean FFRmicro and dPRmicro values were 0.80 and 0.88, respectively. With an FFRmicro ≤ 0.80, the dPRmicro showed a diagnostic accuracy of 79.6%, sensitivity of 74.6%, specificity of 87.5%, positive predictive value of 90.4%, and negative predictive value of 68.6%. The area under the receiver operating characteristic (ROC) curve was 0.894 (95% confidence interval, 0.833-0.956), and the optimal cut-off value for dPRmicro derived from the ROC analysis was 0.90. dPRmicro and FFRmicro values were discordant in 21/103 cases (20.4%). As a multivariable logistic regression analysis was performed, the male sex (vs. female) had a statistically significant association with a dPRmicro-FFRmicro discordance (OR 4.91; 95% CI, 1.04-23.0; P = 0.044). No other factors were found to be significantly associated with the discordance. In conclusion, dPRmicro measured using a microcatheter had good diagnostic accuracy and correlation with FFRmicro, hence, it can be useful for making revascularization decisions. However, re-studies in larger populations will be needed to better understand the properties of diastolic resting index measured using a microcatheter in clinical settings.

Complications of exercise and pharmacologic stress echocardiography

Stress echocardiography is a diagnostic cardiovascular exam that is commonly utilized for multiple indications, including but not limited to the assessment of obstructive coronary artery disease, valvular disease, obstructive hypertrophic cardiomyopathy, and diastolic function. Stress echocardiography can be performed via both exercise and pharmacologic modalities. Exercise stress is performed with either treadmill or bicycle-based exercise. Pharmacologic stress is performed via either dobutamine or vasodilator-mediated (i.e., dipyridamole, adenosine) stress testing. Each of these modalities is associated with a low overall prevalence of major, life-threatening adverse outcomes, though adverse events are most common with dobutamine stress echocardiography. In light of the recent COVID-19 pandemic, the risk of infectious complications to both the patient and stress personnel cannot be negated; however, when certain precautions are taken, the risk of infectious complications appears minimal. In this article, we review each of the stress echocardiographic modalities, examine major potential adverse outcomes and contraindications, assess the risks of stress testing in the setting of a global pandemic, and examine the utilization and safety of stress testing in special patient populations (i.e., language barriers, pediatric patients, pregnancy).

Resting Full-Cycle Ratio versus Fractional Flow Reserve: A SWEDEHEART-Registry-Based Comparison of Two Physiological Indexes for Assessing Coronary Stenosis Severity

The adenosine-requiring physiological index fractional flow reserve (FFR) is the gold-standard method for determining the significance of intermediate lesions, while the resting full-cycle ratio (RFR) is a novel nonhyperaemic index without the need for adenosine administration. The aim of this study was to investigate the degree of concordance between RFR and FFR in indicating the need for revascularisation in patients with intermediate coronary lesions. This was a retrospective, registry-based study utilising data from the SWEDEHEART registry. Patients treated at Ryhov County Hospital in Jönköping, Sweden, between the 1^st of January 2020 and the 30^th of September 2021, were included. The degree of correlation and concordance between RFR and FFR was determined, both when used with a single cut-off (significant stenosis if RFR ≤0.89) and with a hybrid approach (significant stenosis if RFR ≤0.85, not significant if RFR ≥0.94, and FFR measurement when RFR was in the grey zone 0.86-0.93). The study population consisted of 143 patients with 200 lesions. The overall correlation between FFR and RFR was significant (r = 0.715, R² = 0.511, p ≤ 0.01). A strong correlation was seen for lesions in the left anterior descending artery (LAD) and the left circumflex artery (LCX) (r = 0.748 and 0.742, respectively, both p ≤ 0.01), while the correlation in the right coronary artery (RCA) was moderate (r = 0.524, p ≤ 0.01). The overall concordance between FFR and RFR using a single cut-off was 79.0%. With a hybrid cut-off approach, the degree of concordance was 91%, with no need of adenosine in 50.5% of the lesions. In conclusion, there was a strong correlation and a high degree of concordance between FFR and RFR in determining the significance of a stenosis. The use of a hybrid approach could improve the identification of physiologically significant stenoses while minimising the use of adenosine.

Patient and physician preferences for non-invasive diagnostic cardiovascular imaging technologies: a discrete choice experiment

Purpose

Diagnostic imaging techniques have to be selected for their accuracy, efficiency, cost-efficiency, and impact on outcome. But beyond that, the choice of non-invasive cardiovascular imaging tests for diagnosing coronary artery disease also has to respect patient safety and comfort. In this study, we investigated patient and physician preference in relation to the choice of cardiovascular imaging tests.

Results

A total of 211 subjects (148 cardiac patients and 63 physicians) were enrolled and completed a discrete choice experiment. Tests and modalities were deconstructed into 6 attributes (risks and side effects, diagnostic accuracy, patient out-of-pocket cost, type of procedure, type of scanner and test duration). A Sawtooth software choice-based conjoint analysis with hierarchical Bayes estimation was performed and showed the risks and side effects attribute was assigned the most relative importance (30%) when considering patients’ preference. Patients gave notably high value to tests with milder side effects, while preferring to avoid exposure to ionizing radiation and risks associated the use of pharmacological agents inducing direct coronary arteriolar vasodilation. Physicians allocated more importance to the patient out-of-pocket cost attribute (29%). Both patients and physicians valued tests’ risks and side effects, diagnostic accuracy, patient out-of-pocket cost as the three most important attributes, but in diverging order. A market simulation comparing current cardiovascular imaging tests revealed breathing maneuver-enhanced cardiac magnetic resonance had the highest shares of preference in both patients (59.6%) and physicians (32.7%).

Conclusion

A patients’ preference for a particular cardiovascular imaging test was most determined by the risks and side effects, while physicians prioritized less costly tests for their patients. In shared decision-making with patients, physicians should therefore focus on a balanced discussion of risks and side effects associated with cardiovascular imaging tests. Both, patients and physicians would prefer a cardiovascular MR imaging test using a vasoactive breathing maneuver instead of currently used alternatives that require intravenous contrast agents, pharmacological stress, or radiation.

Review of cardiovascular imaging in the Journal of Nuclear Cardiology 2019: Single-photon emission computed tomography

In 2019, the Journal of Nuclear Cardiology published excellent articles pertaining to imaging in patients with cardiovascular disease. In this review, we will summarize a selection of these articles to provide a concise review of the main advancements that have recently occurred in the field and provide the reader with an opportunity to review a wide selection of articles. In the first article of this 2-part series, we focused on publications dealing with positron emission tomography, computed tomography, and magnetic resonance. This review will place emphasis on myocardial perfusion imaging using single-photon emission computed tomography summarizing advances in the field including in diagnosis and prognosis, non-perfusion variables, safety of testing, imaging in patients with heart failure and renal disease.

Quantitative flow ratio-guided strategy versus angiography-guided strategy for percutaneous coronary intervention: Rationale and design of the FAVOR III China trial

BACKGROUND

Quantitative flow ratio (QFR) is a novel angiography-based approach enabling fast computation of fractional flow reserve without use of pressure wire or adenosine. The objective of this investigator-initiated, multicenter, patient- and clinical assessor-blinded randomized trial is to evaluate the efficacy and cost-effectiveness of a QFR-augmented angiography-guided (QFR-guided) strategy versus an angiography-only guided (angiography-guided) strategy for percutaneous coronary intervention (PCI) in patients with coronary artery disease.

METHODS

Approximately 3,830 patients will be randomized in a 1:1 ratio to a QFR-guided or an angiography-guided strategy. Included subjects scheduled for coronary angiography have at least 1 lesion eligible for PCI with 50%-90% stenosis in an artery with ≥2.5 mm reference diameter. Subjects assigned to the QFR-guided strategy will have QFR measured in each interrogated vessel and undergo PCI when QFR ≤0.80, with deferral for lesions with QFR >0.80. Those assigned to the angiography-guided strategy will undergo PCI based on angiography. Optimal medical therapy will be administered to all treated and deferred patients. The primary end point is the 1-year rate of major adverse cardiac events (MACE), a composite of all-cause mortality, any myocardial infarction, or any ischemia-driven revascularization. The major secondary end point is 1-year MACE excluding periprocedural myocardial infarction. Other secondary end points include the individual components of MACE and cost-effectiveness end points. The sample size affords 85% power to demonstrate superiority of QFR guidance compared with angiography guidance.

CONCLUSIONS

The FAVOR III China study will be the first randomized trial to examine the effectiveness and cost-effectiveness of a QFR-guided versus an angiography-guided PCI strategy in coronary artery disease patients.

Current approach to the diagnosis of atherosclerotic coronary artery disease: more questions than answers

Despite its commonality in routine clinical practice, the approach to a diagnosis of atherosclerotic coronary artery disease remains complex and, in part, contentious. The traditional dogma linking ischaemia to hard clinical outcomes has been questioned and reframed over the years; rather than being a predictor of hard clinical outcomes, the degree of ischaemia may simply be a marker of atherosclerotic disease burden. A renewed interest in the imaging of plaque burden has spawned the contemporary role of CT imaging for not only diagnosis and prognosis, but also for dictating downstream management. As the technology develops and evidence expands, decisions on investigative modalities remain centred around patient factors, local availability, test performance and cost. This review summarizes the available methods for diagnosis in the symptomatic patient and provides an overview of the current evidence behind functional and anatomical approaches.

Aminophylline shortage and current recommendations for reversal of vasodilator stress: An ASNC information statement endorsed by SCMR

Pharmacologic reversal of serious or intolerable side effects (SISEs) from vasodilator stress is an important safety and comfort measure for patients experiencing such effects. While typically performed using intravenous aminophylline, recurrent shortages of this agent have led to a greater need to limit its use and consider alternative agents. This information statement provides background and recommendations addressing indications for vasodilator reversal, timing of a reversal agent, incidence of observed SISE with vasodilator stress, clinical and logistical considerations for aminophylline-based reversal, and alternative non-aminophylline based reversal protocols.

Aminophylline shortage and current recommendations for reversal of vasodilator stress: an ASNC information statement endorsed by SCMR

Pharmacologic reversal of serious or intolerable side effects (SISE) from vasodilator stress is an important safety and comfort measure for patients experiencing such effects. While typically performed using intravenous aminophylline, recurrent shortages of this agent have led to a greater need to limit its use and consider alternative agents. This information statement provides background and recommendations addressing indications for vasodilator reversal, timing of a reversal agent, incidence of observed SISE with vasodilator stress, clinical and logistical considerations for aminophylline-based reversal, and alternative non-aminophylline based reversal protocols.

Safety of coronary CT angiography and functional testing for stable chest pain in the PROMISE trial: A randomized comparison of test complications, incidental findings, and radiation dose

BACKGROUND

Coronary computed tomography angiography (CTA) and functional testing strategies for stable chest pain yield similar outcomes; one aspect that may guide test choice is safety.

METHODS

We compared test safety (test complications, incidental findings, and effective radiation dose) between CTA and functional testing as-tested in PROMISE (PROspective Multicenter Imaging Study for Evaluation of Chest Pain). In the subgroup whose physicians intended nuclear stress over other functional tests if randomized to the functional arm, we compared radiation dose of CTA versus nuclear stress and identified characteristics associated with dose.

RESULTS

Of 9470 patients, none had major and <1% had minor complications (CTA: 0.8% [37/4633] vs. functional: 0.6% [27/4837]). CTA identified more incidental findings (11.6% [539/4633] vs. 0.7% [34/4837], p < 0.001), most commonly pulmonary nodules (9.4%, 437/4633). CTA had similar 90-day cumulative radiation dose to functional testing. However, in the subgroup whose physicians intended nuclear stress (CTA 3147; nuclear 3203), CTA had lower median index test (8.8 vs. 12.6 mSv, p < 0.001) and 90-day cumulative (11.6 vs. 13.1 mSv, p < 0.001) dose, independent of patient characteristics. The lowest nuclear doses employed 1-day Tc-99m protocols (12.2 mSv). The lowest CTA doses were at sites performing ≥500 CTAs/year (6.9 mSv) and with advanced (latest available) CT scanners (5.5 mSv).

CONCLUSION

Complications were negligibly rare for both CTA and functional testing. CTA detects more incidental findings. Compared to nuclear stress testing, CTA's lower radiation dose, independent of patient characteristics, makes it an attractive test choice. Radiation dose varies with imaging protocol, indicating opportunities to further reduce dose. (ClinicalTrials.gov number, NCT01174550).

Aminophylline and caffeine for reversal of adverse symptoms associated with regadenoson SPECT MPI

BACKGROUND

Aminophylline shortages led us to compare intravenous (IV) aminophylline with IV and oral (PO) caffeine during routine pharmacologic stress testing with SPECT MPI.

METHODS

We measured presence, duration, and reversal of adverse symptoms and cardiac events following regadenoson administration in consecutive patients randomized to IV aminophylline (100 mg administered over 30-60 seconds), IV caffeine citrate (60 mg infused over 3-5 minutes), or PO caffeine as coffee or diet cola.

RESULTS

Of 241 patients, 152 (63%) received regadenoson reversal intervention. Complete (CR), predominant (PRE), or partial (PR) reversal was observed in 99%. CR by IV aminophylline (87%), IV caffeine (87%), and PO caffeine (78%) were similar (P = NS). Time to CR (162 ± 12.6 seconds, mean ± SD) was similar in treatment arms. PO caffeine was inferior to IV aminophylline for CR + PRE.

CONCLUSIONS

IV aminophylline and IV caffeine provide rapid, safe reversal of regadenoson-induced adverse effects during SPECT MPI. Oral caffeine appeared similarly effective for CR but not for the combined CR + PRE. Our results suggest PO caffeine may be an effective initial strategy for reversal of regadenoson, but IV aminophylline or IV caffeine should be available to optimize symptom reversal as needed.

Use of the Instantaneous Wave-free Ratio or Fractional Flow Reserve in PCI

BACKGROUND

Coronary revascularization guided by fractional flow reserve (FFR) is associated with better patient outcomes after the procedure than revascularization guided by angiography alone. It is unknown whether the instantaneous wave-free ratio (iFR), an alternative measure that does not require the administration of adenosine, will offer benefits similar to those of FFR.

METHODS

We randomly assigned 2492 patients with coronary artery disease, in a 1:1 ratio, to undergo either iFR-guided or FFR-guided coronary revascularization. The primary end point was the 1-year risk of major adverse cardiac events, which were a composite of death from any cause, nonfatal myocardial infarction, or unplanned revascularization. The trial was designed to show the noninferiority of iFR to FFR, with a margin of 3.4 percentage points for the difference in risk.

RESULTS

At 1 year, the primary end point had occurred in 78 of 1148 patients (6.8%) in the iFR group and in 83 of 1182 patients (7.0%) in the FFR group (difference in risk, -0.2 percentage points; 95% confidence interval [CI], -2.3 to 1.8; P<0.001 for noninferiority; hazard ratio, 0.95; 95% CI, 0.68 to 1.33; P=0.78). The risk of each component of the primary end point and of death from cardiovascular or noncardiovascular causes did not differ significantly between the groups. The number of patients who had adverse procedural symptoms and clinical signs was significantly lower in the iFR group than in the FFR group (39 patients [3.1%] vs. 385 patients [30.8%], P<0.001), and the median procedural time was significantly shorter (40.5 minutes vs. 45.0 minutes, P=0.001).

CONCLUSIONS

Coronary revascularization guided by iFR was noninferior to revascularization guided by FFR with respect to the risk of major adverse cardiac events at 1 year. The rate of adverse procedural signs and symptoms was lower and the procedural time was shorter with iFR than with FFR. (Funded by Philips Volcano; DEFINE-FLAIR ClinicalTrials.gov number, NCT02053038 .).

Safety of vasodilator stress myocardial perfusion imaging in patients with elevated cardiac biomarkers

BACKGROUND

While adenosine and dipyridamole as myocardial perfusion imaging (MPI) stress agents have literature supporting their safety in the setting of myocardial infarction (MI), regadenoson does not. Studying a high risk cohort of patients with elevated cardiac biomarkers may shed light on potential safety issues of these agents which might also affect lower risk cohorts.

METHODS

All patients who had undergone a clinically indicated stress MPI study at two academic centers from 1/1/2010 through 12/31/2012 with elevated troponin ≤7 days prior to testing were included. The primary endpoint was a composite of death, non-fatal MI, congestive heart failure (CHF), stroke, ventricular arrhythmias, atrial fibrillation/flutter, or atrioventricular block requiring intervention within 24 h of testing.

RESULTS

Of the 703 stress MPI studies that met inclusion criteria, 360 (51.2%), 199 (28.3%), 74 (10.5%), 9 (1.3%), and 61 (8.7%) underwent regadenoson, dipyridamole, adenosine, dobutamine, and exercise stress, respectively. The primary endpoint occurred in 11 (1.6%) patients with an incidence of 1.4% (n = 5), 1.0% (n = 2), 1.4% (n = 1), 11.1% (n = 1), and 3.3% (n = 2) following regadenoson, dipyridamole, adenosine, dobutamine, and exercise stress, respectively (P = 0.137). The adverse events included non-fatal MI in 7 (1.0%) patients, death in 1 (0.1%) patient, CHF in 1 (0.1%) patient, ventricular arrhythmia in 1 (0.1%) patient, and atrial arrhythmia in 1 (0.1%) patient.

CONCLUSION

In the setting of elevated troponin, serious complications associated with either exercise or vasodilator stress testing appear to be relatively rare with no increased risk attributable to a particular vasodilator agent.

Non-invasive assessment of low- and intermediate-risk patients with chest pain

Coronary artery disease (CAD) remains a significant global public health burden despite advancements in prevention and therapeutic strategies. Common non-invasive imaging modalities, anatomic and functional, are available for the assessment of patients with stable chest pain. Exercise electrocardiography is a long-standing method for evaluation for CAD and remains the initial test for the majority of patients who can exercise adequately with a baseline interpretable electrocardiogram. The addition of cardiac imaging to exercise testing provides incremental benefit for accurate diagnosis for CAD and is particularly useful in patients who are unable to exercise adequately and/or have uninterpretable electrocardiograms. Radionuclide myocardial perfusion imaging and echocardiography with exercise or pharmacological stress provide high sensitivity and specificity in the detection and further risk stratification of patients with CAD. Recently, coronary computed tomography angiography has demonstrated its growing role to rule out significant CAD given its high negative predictive value. Although less available, stress cardiac magnetic resonance provides a comprehensive assessment of cardiac structure and function and provides a high diagnostic accuracy in the detection of CAD. The utilization of non-invasive testing is complex due to various advantages and limitations, particularly in the assessment of low- and intermediate-risk patients with chest pain, where no single study is suitable for all patients. This review will describe currently available non-invasive modalities, along with current evidence-based guidelines and appropriate use criteria in the assessment of low- and intermediate-risk patients with suspected, stable CAD.

Safety of regadenoson in patients with severe chronic obstructive pulmonary disease

OBJECTIVE

To assess the safety of regadenoson, a selective agonist of A2A adenosine receptors, combined with low-level exercise in subjects with severe chronic obstructive pulmonary disease (COPD), referred for myocardial perfusion imaging (MPI).

METHODS

We studied prospectively 12 male patients with severe COPD. Stress was 4min of low-level exercise with bolus injection of regadenoson (0.4mg) at 1.5min, followed by (99m)Tc-MPI agent injection. Demographics, medical history, lung medications, adverse events, oxygen saturation (SatO2), MPI findings for coronary artery disease (CAD), and changes in systolic blood pressure (SBP), and heart rate (HR) were registered.

RESULTS

The observed adverse event profile of regadenoson was similar to that of patients with mild-moderate COPD. There was no clinical exacerbation of COPD. Adverse events were self-limiting: dyspnea (33.3%), fatigue (25.0%), chest pain, headache (16.7%, respectively), and gastrointestinal discomfort, dry mouth, flushing, feeling hot and dizziness (8.3%, respectively). 25.0% of patients did not report any symptoms. We observed significant increases in SBP and HR from baseline (142.6mmHg±22.3 vs 152.5mmHg±18.5, and 80 b.p.m.±18 vs 105 b.p.m.±22, respectively; p<0.05).

CONCLUSIONS

Regadenoson combined with low-level exercise is safe and well tolerated in stable patients with severe COPD undergoing MPI.