Rethinking False Positive Exercise Electrocardiographic Stress Tests by Assessing Coronary Microvascular Function

BACKGROUND

Exercise electrocardiographic stress testing (EST) has historically been validated against the demonstration of obstructive coronary artery disease. However, myocardial ischemia can occur because of coronary microvascular dysfunction (CMD) in the absence of obstructive coronary artery disease.

OBJECTIVES

The aim of this study was to assess the specificity of EST to detect an ischemic substrate against the reference standard of coronary endothelium-independent and endothelium-dependent microvascular function in patients with angina with nonobstructive coronary arteries (ANOCA).

METHODS

Patients with ANOCA underwent invasive coronary physiological assessment using adenosine and acetylcholine. CMD was defined as impaired endothelium-independent and/or endothelium-dependent function. EST was performed using a standard Bruce treadmill protocol, with ischemia defined as the appearance of ≥0.1-mV ST-segment depression 80 ms from the J-point on electrocardiography. The study was powered to detect specificity of ≥91%.

RESULTS

A total of 102 patients were enrolled (65% women, mean age 60 ± 8 years). Thirty-two patients developed ischemia (ischemic group) during EST, whereas 70 patients did not (nonischemic group); both groups were phenotypically similar. Ischemia during EST was 100% specific for CMD. Acetylcholine flow reserve was the strongest predictor of ischemia during exercise. Using endothelium-independent and endothelium-dependent microvascular dysfunction as the reference standard, the false positive rate of EST dropped to 0%.

CONCLUSIONS

In patients with ANOCA, ischemia on EST was highly specific of an underlying ischemic substrate. These findings challenge the traditional belief that EST has a high false positive rate.

ChaMP-CMD: A Phenotype-Blinded, Randomized Controlled, Cross-Over Trial

BACKGROUND

Angina with nonobstructive coronary arteries is a common condition for which no effective treatment has been established. We hypothesized that the measurement of coronary flow reserve (CFR) allows identification of patients with angina with nonobstructive coronary arteries who would benefit from anti-ischemic therapy.

METHODS

Patients with angina with nonobstructive coronary arteries underwent blinded invasive CFR measurement and were randomly assigned to receive 4 weeks of amlodipine or ranolazine. After a 1-week washout, they crossed over to the other drug for 4 weeks; final assessment was after the cessation of study medication for another 4 weeks. The primary outcome was change in treadmill exercise time, and the secondary outcome was change in Seattle Angina Questionnaire summary score in response to anti-ischemic therapy. Analysis was on a per protocol basis according to the following classification: coronary microvascular disease (CMD group) if CFR<2.5 and reference group if CFR≥2.5. The study protocol was registered before the first patient was enrolled (International Standard Randomised Controlled Trial Number: ISRCTN94728379).

RESULTS

Eighty-seven patients (61±8 years of age; 62% women) underwent random assignment (57 CMD group and 30 reference group). Baseline exercise time and Seattle Angina Questionnaire summary scores were similar between groups. The CMD group had a greater increment (delta) in exercise time than the reference group in response to both amlodipine (difference in delta, 82 s [95% CI, 37-126 s]; P<0.001) and ranolazine (difference in delta, 68 s [95% CI, 21-115 s]; P=0.005). The CMD group reported a greater increment (delta) in Seattle Angina Questionnaire summary score than the reference group in response to ranolazine (difference in delta, 7 points [95% CI, 0-15]; P=0.048), but not to amlodipine (difference in delta, 2 points [95% CI, -5 to 8]; P=0.549).

CONCLUSIONS

Among phenotypically similar patients with angina with nonobstructive coronary arteries, only those with an impaired CFR derive benefit from anti-ischemic therapy. These findings support measurement of CFR to diagnose and guide management of this otherwise heterogeneous patient group.

The everolimus eluting Synergy MegatronTM drug-eluting stent platform: Early outcomes from the European Synergy MegatronTM Implanters' Registry

BACKGROUND

The Synergy MegatronTM is an everolimus-drug eluting stent that may offer advantages in the treatment of aorto-ostial disease and large proximal vessels.

AIMS

To report the short- to medium-term clinical outcomes from the European Synergy MegatronTM Implanters' Registry.

METHODS

This registry was an investigator-initiated study conducted at 14 European centers. The primary outcome was target lesion failure (TLF), defined as the composite of cardiovascular death, target vessel myocardial infarction (MI), and target lesion revascularisation.

RESULTS

Five hundred seventy-five patients underwent PCI with MegatronTM between 2019 and 2021. Patients were 69 ± 12 years old, 26% had diabetes mellitus, 24% had moderate-severe left ventricular impairment and 59% presented with an acute coronary syndrome. 15% were deemed prohibitively high risk for surgical revascularisation. The target vessel involved the left main stem in 55%, the ostium of the RCA in 13% and was a true bifurcation (Medina 1,1,1) in 50%.  At 1 year, TLF was observed in 40 patients, with 26 (65%) occurring within the first 30 days. The cumulative incidence of TLF was 4.5% at 30 days and 8.6% (95% CI 6.3-11.7) at 1 year. The incidence of stent thrombosis was 0.5% with no late stent thromboses. By multivariate analysis, the strongest independent predictors of TLF were severe left ventricular impairment (HR 3.43, 95% CI: 1.67-6.76, p < 0.001) and a target vessel involving the left main (HR 4.00 95% CI 1.81-10.15 p = 0.001).

CONCLUSIONS

Use of the Synergy MegatronTM everolimus eluting stent in a 'real-world' setting shows favorable outcomes at 30 days and 1 year.

Assessment and Management of Ischaemic Heart Disease in Non-Cardiac Surgery

In the setting of non-cardiac surgery, cardiac complications contribute to over a third of perioperative deaths. With over 230 million major surgeries performed annually, and an increasing prevalence of cardiovascular risk factors and ischaemic heart disease, the incidence of perioperative myocardial infarction is also rising. The recent European Society of Cardiology guidelines on cardiovascular risk in noncardiac surgery elevated practices aiming to identify those at most risk, including biomarker monitoring and stress testing. However the current evidence base on if, and how, the risk of cardiac events can be modified is lacking. This review focuses on patient, surgical and cardiac risk assessment, as well as exploring the data on perioperative revascularization and other risk-reduction strategies.

Viability and Outcomes With Revascularization or Medical Therapy in Ischemic Ventricular Dysfunction: A Prespecified Secondary Analysis of the REVIVED-BCIS2 Trial

Importance

In the Revascularization for Ischemic Ventricular Dysfunction (REVIVED-BCIS2) trial, percutaneous coronary intervention (PCI) did not improve outcomes for patients with ischemic left ventricular dysfunction. Whether myocardial viability testing had prognostic utility for these patients or identified a subpopulation who may benefit from PCI remained unclear.

Objective

To determine the effect of the extent of viable and nonviable myocardium on the effectiveness of PCI, prognosis, and improvement in left ventricular function.

Design, Setting, and Participants

Prospective open-label randomized clinical trial recruiting between August 28, 2013, and March 19, 2020, with a median follow-up of 3.4 years (IQR, 2.3-5.0 years). A total of 40 secondary and tertiary care centers in the United Kingdom were included. Of 700 randomly assigned patients, 610 with left ventricular ejection fraction less than or equal to 35%, extensive coronary artery disease, and evidence of viability in at least 4 myocardial segments that were dysfunctional at rest and who underwent blinded core laboratory viability characterization were included. Data analysis was conducted from March 31, 2022, to May 1, 2023.

Intervention

Percutaneous coronary intervention in addition to optimal medical therapy.

Main Outcomes and Measures

Blinded core laboratory analysis was performed of cardiac magnetic resonance imaging scans and dobutamine stress echocardiograms to quantify the extent of viable and nonviable myocardium, expressed as an absolute percentage of left ventricular mass. The primary outcome of this subgroup analysis was the composite of all-cause death or hospitalization for heart failure. Secondary outcomes were all-cause death, cardiovascular death, hospitalization for heart failure, and improved left ventricular function at 6 months.

Results

The mean (SD) age of the participants was 69.3 (9.0) years. In the PCI group, 258 (87%) were male, and in the optimal medical therapy group, 277 (88%) were male. The primary outcome occurred in 107 of 295 participants assigned to PCI and 114 of 315 participants assigned to optimal medical therapy alone. There was no interaction between the extent of viable or nonviable myocardium and the effect of PCI on the primary or any secondary outcome. Across the study population, the extent of viable myocardium was not associated with the primary outcome (hazard ratio per 10% increase, 0.98; 95% CI, 0.93-1.04) or any secondary outcome. The extent of nonviable myocardium was associated with the primary outcome (hazard ratio, 1.07; 95% CI, 1.00-1.15), all-cause death, cardiovascular death, and improvement in left ventricular function.

Conclusions and Relevance

This study found that viability testing does not identify patients with ischemic cardiomyopathy who benefit from PCI. The extent of nonviable myocardium, but not the extent of viable myocardium, is associated with event-free survival and likelihood of improvement of left ventricular function.

Trial Registration

ClinicalTrials.gov Identifier: NCT01920048.

Coronary Wave Intensity Analysis as an Invasive and Vessel-Specific Index of Myocardial Viability

BACKGROUND

Coronary angiography and viability testing are the cornerstones of diagnosing and managing ischemic cardiomyopathy. At present, no single test serves both needs. Coronary wave intensity analysis interrogates both contractility and microvascular physiology of the subtended myocardium and therefore has the potential to fulfil the goal of completely assessing coronary physiology and myocardial viability in a single procedure. We hypothesized that coronary wave intensity analysis measured during coronary angiography would predict viability with a similar accuracy to late-gadolinium-enhanced cardiac magnetic resonance imaging.

METHODS

Patients with a left ventricular ejection fraction ≤40% and extensive coronary disease were enrolled. Coronary wave intensity analysis was assessed during cardiac catheterization at rest, during adenosine-induced hyperemia, and during low-dose dobutamine stress using a dual pressure-Doppler sensing coronary guidewire. Scar burden was assessed with cardiac magnetic resonance imaging. Regional left ventricular function was assessed at baseline and 6-month follow-up after optimization of medical-therapy±revascularization, using transthoracic echocardiography. The primary outcome was myocardial viability, determined by the retrospective observation of functional recovery.

RESULTS

Forty participants underwent baseline physiology, cardiac magnetic resonance imaging, and echocardiography, and 30 had echocardiography at 6 months; 21/42 territories were viable on follow-up echocardiography. Resting backward compression wave energy was significantly greater in viable than in nonviable territories (-5240±3772 versus -1873±1605 W m-2 s-1, P<0.001), and had comparable accuracy to cardiac magnetic resonance imaging for predicting viability (area under the curve 0.812 versus 0.757, P=0.649); a threshold of -2500 W m-2 s-1 had 86% sensitivity and 76% specificity.

CONCLUSIONS

Backward compression wave energy has accuracy similar to that of late-gadolinium-enhanced cardiac magnetic resonance imaging in the prediction of viability. Coronary wave intensity analysis has the potential to streamline the management of ischemic cardiomyopathy, in a manner analogous to the effect of fractional flow reserve on the management of stable angina.

Percutaneous Revascularization for Ischemic Left Ventricular Dysfunction

BACKGROUND

Whether revascularization by percutaneous coronary intervention (PCI) can improve event-free survival and left ventricular function in patients with severe ischemic left ventricular systolic dysfunction, as compared with optimal medical therapy (i.e., individually adjusted pharmacologic and device therapy for heart failure) alone, is unknown.

METHODS

We randomly assigned patients with a left ventricular ejection fraction of 35% or less, extensive coronary artery disease amenable to PCI, and demonstrable myocardial viability to a strategy of either PCI plus optimal medical therapy (PCI group) or optimal medical therapy alone (optimal-medical-therapy group). The primary composite outcome was death from any cause or hospitalization for heart failure. Major secondary outcomes were left ventricular ejection fraction at 6 and 12 months and quality-of-life scores.

RESULTS

A total of 700 patients underwent randomization - 347 were assigned to the PCI group and 353 to the optimal-medical-therapy group. Over a median of 41 months, a primary-outcome event occurred in 129 patients (37.2%) in the PCI group and in 134 patients (38.0%) in the optimal-medical-therapy group (hazard ratio, 0.99; 95% confidence interval [CI], 0.78 to 1.27; P = 0.96). The left ventricular ejection fraction was similar in the two groups at 6 months (mean difference, -1.6 percentage points; 95% CI, -3.7 to 0.5) and at 12 months (mean difference, 0.9 percentage points; 95% CI, -1.7 to 3.4). Quality-of-life scores at 6 and 12 months appeared to favor the PCI group, but the difference had diminished at 24 months.

CONCLUSIONS

Among patients with severe ischemic left ventricular systolic dysfunction who received optimal medical therapy, revascularization by PCI did not result in a lower incidence of death from any cause or hospitalization for heart failure. (Funded by the National Institute for Health and Care Research Health Technology Assessment Program; REVIVED-BCIS2 ClinicalTrials.gov number, NCT01920048.).

The Impact of a Dedicated Chronic Total Occlusion PCI Program on Heart Team Decision Making

BACKGROUND

Guidelines endorse a heart team (HT) approach to standardize the decision-making process for patients with complex coronary artery disease (CAD). With percutaneous treatment options for complex CAD increasing, we hypothesized that practice had changed over the past decade-and that more individuals, previously deemed too high risk for intervention, would now be referred for either surgical or percutaneous revascularization.

METHODS

This observational study was conducted at St Thomas' Hospital (London, United Kingdom). All patients discussed at HT meetings were recorded and treatment recommendations audited. A subset of historic cases was selected for blinded, repeat discussion.

RESULTS

From April 2018 to 2019, a total of 52 HT meetings discussing 375 cases were held. Patients tended to be male, with a majority demonstrating multivessel CAD in the context of preserved left ventricular function. SYNTAX scores were balanced across the tertiles. Thirty-five percent of patients had at least 1 chronic total occlusion (mean J-CTO, 3 [interquartile range, 2-3]), affecting the right coronary artery in 60%. Fifteen historic patients with isolated CTOs were re-presented an average of 8 years later; only 3 patients received the same outcome, with 80% now receiving a recommendation for revascularization over medical therapy.

CONCLUSIONS

A dedicated program supporting complex coronary intervention is associated with a change in treatment recommendations issued by the local HT. In line with international guidelines, this might indicate that any complex or multivessel CAD should be discussed at HT meetings with, ideally, the presence of CTO operators.

Coronary Revascularization and Out-of-hospital Cardiac Arrest: Past, Present and Future

Cardiologists and the cardiac catheter laboratory have key roles to play in the management of patients after out-of-hospital cardiac arrest (OHCA). Although immediate catheter laboratory activation is the standard of care in cardiogenic shock and ST elevation myocardial infarction, the majority of patients will present without these features and with an uncertain diagnosis. Even in the latter, early assessment and invasive management may be beneficial, but this is counterbalanced by significant resource utilization, potential to cause harm and the possibility that any diagnostic or therapeutic gains are offset by a poor neurological outcome. Past consensus on the management of the OHCA patient without ST elevation or cardiogenic shock is being challenged by emerging results from new trials in this field. Further randomized trials are ongoing, and are expected to deliver robust data from over 4,000 patients, allowing us to further refine the optimal management strategy in this challenging cohort. This article describes the benefits and pitfalls of a strategy of immediate coronary angiography in these patients, examines the recently published COACT and TOMAHAWK trials in detail, and describes a framework with which to approach the patient after resuscitated OHCA, based on the available evidence to date.

FLOWER-MI and the root of the problem with non-culprit revascularisation

How do we reduce cardiac death and myocardial infarction by percutaneous coronary intervention (PCI) in coronary heart disease? Although the interventional community continues to grapple with this question in stable angina, the benefits of PCI for non-culprit lesions found at ST-elevation myocardial infarction are established. Is it then wishful thinking that an index developed in stable coronary disease, for identifying lesions capable of causing ischaemia will show an incremental benefit over angiographically guided non-culprit PCI? This is the question posed by the recently published FLOW Evaluation to Guide Revascularization in Multi-vessel ST-elevation Myocardial Infarction (FLOWER-MI) trial. We examine the trial design and results; ask if there is any relationship between the baseline physiological significance of a non-culprit lesion and vulnerability to future myocardial infarction; and consider if more sophisticated methods can help guide or defer non-culprit revascularisation.

Calcium Modification Techniques in Complex Percutaneous Coronary Intervention

Percutaneous coronary intervention is the most common mode of revascularization and is increasingly undertaken in high-risk subsets, including the elderly. The presence of coronary artery calcification is increasingly observed and significantly limits technical success. The mechanisms for this are multi-factorial, including increased arterial wall stiffness and impaired delivery of devices, leading to suboptimal stent delivery, deployment, and expansion which are harbingers for increased risk of in-stent restenosis and stent thrombosis. Although conventional balloon pretreatment techniques aim to mitigate this risk by modifying the lesion before stent placement, many lesions remain resistant to conventional strategies, due to the severity of calcification. There have been several substantial technological advancements in calcium modification methods in recent years, which have allowed improved procedural success with low periprocedural complication rates. This review will summarize the current adjunctive modification technologies that can be employed to improve technical outcomes in percutaneous coronary intervention in calcific disease and the evidence supporting these tools.

Iterative Improvement and Marginal Gains in Coronary Revascularisation: Is Robot-assisted Percutaneous Coronary Intervention the New Hope?

Percutaneous coronary intervention (PCI) has undergone a rapid and adaptive evolution since its introduction into clinical practice more than 40 years ago. It is the most common mode of coronary revascularisation in use, with the scope, breadth and constellation of disease being treated increasing markedly over time. This has principally been driven by improvements in technology, engineering and training in the field, which has facilitated more complex PCI procedures to be undertaken safely. Robot-assisted PCI represents the next paradigm shift in contemporary PCI practice. It has the ability to enhance procedural accuracy for the patient while improving radiation safety and ergonomics for the operator. This state-of-the-art review outlines the current position and future potential of robot-assisted PCI.

Changes in contractility determine coronary haemodynamics in dyssynchronous left ventricular heart failure, not vice versa

BACKGROUND

Biventricular pacing has been shown to increase both cardiac contractility and coronary flow acutely but the causal relationship is unclear. We hypothesised that changes in coronary flow are secondary to changes in cardiac contractility. We sought to examine this relationship by modulating coronary flow and cardiac contractility.

METHODS

Contractility and lusitropy were altered by varying the location of pacing in 8 patients. Coronary autoregulation was transiently disabled with intracoronary adenosine. Simultaneous coronary flow velocity, coronary pressure and left ventricular pressure data were measured in the different pacing settings with and without hyperaemia and wave intensity analysis performed.

RESULTS

Multisite pacing was effective at altering left ventricular contractility and lusitropy (pos. dp/dtmax -13% to +10% and neg. dp/dtmax -15% to +17% compared to baseline). Intracoronary adenosine decreased microvascular resistance (362.5 mm Hg/s/m to 156.7 mm Hg/s/m, p < 0.001) and increased LAD flow velocity (22 cm/s vs 45 cm/s, p < 0.001) but did not acutely change contractility or lusitropy. The magnitude of the dominant accelerating wave, the Backward Expansion Wave, was proportional to the degree of contractility as well as lusitropy (r = 0.47, p < 0.01 and r = -0.50, p < 0.01). Perfusion efficiency (the proportion of accelerating waves) increased at hyperaemia (76% rest vs 81% hyperaemia, p = 0.04). Perfusion efficiency correlated with contractility and lusitropy at rest (r = 0.43 & -0.50 respectively, p = 0.01) and hyperaemia (r = 0.59 & -0.6, p < 0.01).

CONCLUSIONS

Acutely increasing coronary flow with adenosine in patients with systolic heart failure does not increase contractility. Changes in coronary flow with biventricular pacing are likely to be a consequence of enhanced cardiac contractility from resynchronization and not vice versa.

Physiology-Guided Management of Serial Coronary Artery Disease: A Review

Importance

Ischemia-guided revascularization is the cornerstone of contemporary management of coronary artery disease and has evolved from noninvasive functional evaluation to real-time assessment with invasive physiological indices during diagnostic catheterization. However, serial/diffuse disease is common, and revascularization decisions often need to be made about individual lesions within the same vessel. It is unclear whether current physiological techniques, such as fractional flow reserve, can be reliably used to discern the individual contribution of lesions within a serially diseased vessel with erroneous measurements, potentially leading to suboptimal revascularization decisions. This review addresses the application of physiological techniques to serial coronary disease, highlighting challenges and potential solutions.

Observations

Physiological indices, such as fractional flow reserve, are well validated and correlated with clinical outcomes; however, the challenging physiology of serial stenoses makes it difficult to apply conventional techniques to identify the physiological significance of individual lesions. The 2 methods are most accurate in assessing serial disease are the manual pullback, with treatment of the greatest pressure gradient, or adopting the use of a large disease-free side branch to isolate the significance of the proximal lesion in the context of serial disease involving the left main coronary artery. In addition, resting indices, such as instantaneous wave-free ratio, have theoretical benefits that may make them more reliable in serial disease, with further data awaited.

Conclusions and Relevance

Serial coronary artery disease is common, and physiological assessment is prone to errors. The future, whether it be in improving the interpretation of fractional flow reserve, using resting indices such as instantaneous wave-free ratio, or examining novel flow-based resistance indices, will hopefully improve our management of this common yet unresolved clinical conundrum. In the meantime, revascularisation decisions in this challenging scenario should focus on clinical presentation and physiologic evaluation using a pressure-wire pullback maneuver and left main disease-free side branch where appropriate.

Doppler Versus Thermodilution-Derived Coronary Microvascular Resistance to Predict Coronary Microvascular Dysfunction in Patients With Acute Myocardial Infarction or Stable Angina Pectoris

Coronary microvascular resistance is increasingly measured as a predictor of clinical outcomes, but there is no accepted gold-standard measurement. We compared the diagnostic accuracy of 2 invasive indices of microvascular resistance, Doppler-derived hyperemic microvascular resistance (hMR) and thermodilution-derived index of microcirculatory resistance (IMR), at predicting microvascular dysfunction. A total of 54 patients (61 ± 10 years) who underwent cardiac catheterization for stable coronary artery disease (n = 10) or acute myocardial infarction (n = 44) had simultaneous intracoronary pressure, Doppler flow velocity and thermodilution flow data acquired from 74 unobstructed vessels, at rest and during hyperemia. Three independent measurements of microvascular function were assessed, using predefined dichotomous thresholds: (1) coronary flow reserve (CFR), the average value of Doppler- and thermodilution-derived CFR; (2) cardiovascular magnetic resonance (CMR) derived myocardial perfusion reserve index; and (3) CMR-derived microvascular obstruction. hMR correlated with IMR (rho = 0.41, p <0.0001). hMR had better diagnostic accuracy than IMR to predict CFR (area under curve [AUC] 0.82 vs 0.58, p <0.001, sensitivity and specificity 77% and 77% vs 51% and 71%) and myocardial perfusion reserve index (AUC 0.85 vs 0.72, p = 0.19, sensitivity and specificity 82% and 80% vs 64% and 75%). In patients with acute myocardial infarction, the AUCs of hMR and IMR at predicting extensive microvascular obstruction were 0.83 and 0.72, respectively (p = 0.22, sensitivity and specificity 78% and 74% vs 44% and 91%). We conclude that these 2 invasive indices of coronary microvascular resistance only correlate modestly and so cannot be considered equivalent. In our study, the correlation between independent invasive and noninvasive measurements of microvascular function was better with hMR than with IMR.

Physiology of Angina and Its Alleviation With Nitroglycerin: Insights From Invasive Catheter Laboratory Measurements During Exercise

BACKGROUND

The mechanisms governing exercise-induced angina and its alleviation by the most commonly used antianginal drug, nitroglycerin, are incompletely understood. The purpose of this study was to develop a method by which the effects of antianginal drugs could be evaluated invasively during physiological exercise to gain further understanding of the clinical impact of angina and nitroglycerin.

METHODS

Forty patients (mean age, 65.2±7.6 years) with exertional angina and coronary artery disease underwent cardiac catheterization via radial access and performed incremental exercise using a supine cycle ergometer. As they developed limiting angina, sublingual nitroglycerin was administered to half the patients, and all patients continued to exercise for 2 minutes at the same workload. Throughout exercise, distal coronary pressure and flow velocity and central aortic pressure were recorded with sensor wires.

RESULTS

Patients continued to exercise after nitroglycerin administration with less ST-segment depression (P=0.003) and therefore myocardial ischemia. Significant reductions in afterload (aortic pressure, P=0.030) and myocardial oxygen demand were seen (tension-time index, P=0.024; rate-pressure product, P=0.046), as well as an increase in myocardial oxygen supply (Buckberg index, P=0.017). Exercise reduced peripheral arterial wave reflection (P<0.05), which was not further augmented by the administration of nitroglycerin (P=0.648). The observed increases in coronary pressure gradient, stenosis resistance, and flow velocity did not reach statistical significance; however, the diastolic velocity-pressure gradient relation was consistent with a significant increase in relative stenosis severity (k coefficient, P<0.0001), in keeping with exercise-induced vasoconstriction of stenosed epicardial segments and dilatation of normal segments, with trends toward reversal with nitroglycerin.

CONCLUSIONS

The catheterization laboratory protocol provides a model to study myocardial ischemia and the actions of novel and established antianginal drugs. Administration of nitroglycerin causes changes in the systemic and coronary circulation that combine to reduce myocardial oxygen demand and to increase supply, thereby attenuating exercise-induced ischemia. Designing antianginal therapies that exploit these mechanisms may provide new therapeutic strategies.

Effects of initial body mass index on development of gestational diabetes in a rural Sri Lankan population: A case-control study

AIM

High pre-pregnancy body mass index (BMI) and excessive pregnancy weight gain lead to higher incidence of gestational diabetes mellitus (GDM). Aim of the study was to assess the effects of initial BMI and pregnancy weight gain on development of GDM in a rural Sri Lankan population. It was also hypothesized that these effects could be more pronounced in shorter mothers.

METHODS

A case-control study was conducted at two rural hospitals in Sri Lanka. A case was defined as a pregnant mother admitted for the completion of pregnancy and diagnosed to have GDM (n=99). A similar group of mothers without GDM were recruited as controls (n=336). Data were collected through health records and direct interviews.

RESULTS

Mean age of GDM and non-GDM mothers were 32.8 years 28.1 years, respectively. High pre-pregnancy BMI was a significant risk for GDM, with a rising trend with increasing BMI. In contrast to underweight mothers, the risk increases from normal weight [odds ratio (OR)=6.6, 95% confidence interval (CI) 2.2-19.4, p<0.01], overweight (OR=17.1, 95% CI 5.8-49.9, p<0.01) and to obese (OR=32.4, 95% CI 10.0-104.5, p<0.01). There was no significant difference in weight gain across mother's height groups. Height or leg length did not show an association with GDM. Family history of diabetes and past GDM were associated with GDM. GDM mothers had higher likelihood for cesarian deliveries, and babies with higher birth weight.

CONCLUSION

The pre-pregnancy BMI was the most important modifiable risk factor for GDM, and it should be the main preventive measure.

Effects of Epicardial and Endocardial Cardiac Resynchronization Therapy on Coronary Flow: Insights From Wave Intensity Analysis

Background

The increase in global coronary flow seen with conventional biventricular pacing is mediated by an increase in the dominant backward expansion wave (BEW). Little is known about the determinants of flow in the left‐sided epicardial coronary arteries beyond this or the effect of endocardial pacing stimulation on coronary physiology.

Methods and Results

Eleven patients with a chronically implanted biventricular pacemaker underwent an acute hemodynamic and electrophysiological study. Five of 11 patients also took part in a left ventricular endocardial pacing protocol at the same time. Conventional biventricular pacing, delivered epicardially from the coronary sinus, resulted in a 9% increase in flow (average peak velocity) in the left anterior descending artery (LAD), mediated by a 13% increase in the area under the BEW (P=0.004). Endocardial pacing resulted in a 27% increase in LAD flow, mediated by a 112% increase in the area under the forward compression wave (FCW) and a 43% increase in the area under the BEW (P=0.048 and P=0.036, respectively). There were no significant changes in circumflex parameters. Conventional biventricular pacing resulted in homogenization of timing of coronary flow compared with baseline (mean difference in time to peak in the LAD versus circumflex artery: FCW 39 ms [baseline] versus 3 ms [conventional biventricular pacing], P=0.008; BEW 47 ms [baseline] versus 8 ms [conventional biventricular pacing], P=0.004).

Conclusions

Epicardial and endocardial pacing result in increased coronary flow in the left anterior descending artery and homogenization of the timing of waves that determine flow in the LAD and the circumflex artery. The increase in both the FCW and the BEW with endocardial pacing may be the result of a more physiological activation pattern than that of epicardial pacing, which resulted in an increase of only the BEW.

What's Age Got to do with it? A Review of Contemporary Revascularization in the Elderly

Currently a quarter of all patients treated with percutanous coronary intervention (PCI) are aged >75 years, with this proportion steadily growing. This subset of patients have a number of unique characteristics, such as a greater number of cardiovascular risk factors and frequently a larger burden of coronary artery disease, when compared to younger patients, therefore potentially deriving increased benefit from revascularization. Nonetheless this population are also more likely to experience procedural complications, secondary to age-related physiological alterations, increased frailty and increased prevalence of other co-morbidities. This article reviews the various aspects and data available to clinicians pertaining to and guiding revascularization in the elderly, including the use of adjuvant pharmacotherapy, specific considerations when considering age-related physiology, and revascularization in acute coronary syndromes.

Ischemic preconditioning-an unfulfilled promise

Myocardial reperfusion injury has been identified as a key determinant of myocardial infarct size in patients undergoing percutaneous or surgical interventions. Although the molecular mechanisms underpinning reperfusion injury have been elucidated, attempts at translating this understanding into clinical benefit for patients undergoing cardiac interventions have produced mixed results. Ischemic conditioning has been applied before, during, or after an ischemic insult to the myocardium and has taken the form of local induction of ischemia or ischemia of distant tissues. Clinical studies have confirmed the safety of differing conditioning techniques, but the benefit of such techniques in reducing hard clinical event rates has produced mixed results. The aim of this article is to review the role of ischemic conditioning in patients undergoing percutaneous and surgical coronary revascularization.

Ischemic burden by 3-dimensional myocardial perfusion cardiovascular magnetic resonance: comparison with myocardial perfusion scintigraphy

BACKGROUND

The extent and severity of ischemia on myocardial perfusion scintigraphy (MPS) is commonly used to risk-stratify patients with coronary artery disease. Estimation of ischemic burden by cardiovascular magnetic resonance (CMR) with conventional 2-dimensional myocardial perfusion methods is limited by incomplete cardiac coverage. More recently developed 3-dimensional (3D) myocardial perfusion CMR, however, provides whole-heart coverage. The aim of this study was to compare ischemic burden on 3D myocardial perfusion CMR with (99m)Tc-tetrofosmin MPS.

METHODS AND RESULTS

Forty-five patients who had undergone clinically indicated MPS underwent rest and adenosine stress 3D myocardial perfusion and late gadolinium enhancement CMR. Summed stress and rest scores were calculated for MPS and CMR using a 17-segment model and expressed as a percentage of the maximal possible score. Ischemic burden was defined as the difference between stress and rest scores. 3D myocardial perfusion CMR and MPS agreed in 38 of the 45 patients for the detection of any inducible ischemia. The mean ischemic burden for MPS and CMR was similar (7.5±8.9% versus 6.8±9.5%, respectively, P=0.82) with a strong correlation between techniques (rs=0.70, P<0.001). In a subset of 33 patients who underwent clinically indicated invasive coronary angiography, sensitivities and specificities of the 2 techniques to detect angiographic coronary artery disease were similar (McNemar P=0.45).

CONCLUSIONS

3D myocardial perfusion CMR is an alternative to MPS for detecting the presence and rating the severity of ischemia.

Prognostic utility of BCIS myocardial jeopardy score for classification of coronary disease burden and completeness of revascularization

Several coronary disease scoring systems have been developed to predict procedural risk during revascularization. Many vary in complexity, do not specifically account for myocardium at risk, and are not applicable across all patient subsets. The British Cardiovascular Intervention Society myocardial jeopardy score (BCIS-JS) addresses these limitations and is applicable to all patients, including those with coronary artery bypass grafts or left main stem disease. We assessed the prognostic relevance of the BCIS-JS in patients undergoing percutaneous coronary intervention (PCI). A total of 663 patients who underwent PCI with previous left ventricular function assessment were retrospectively assessed for inclusion, incorporating 221 with previous coronary artery bypass grafting. Blinded observers calculated the BCIS-JS, before (BCIS-JS(PRE)) and after (BCIS-JS(POST)) PCI, using the revascularization index (RI) (RI = [BCIS-JS(PRE) - BCIS-JS(POST)]/BCIS-JS(PRE)), quantifying the extent of revascularization, 1 indicating full revascularization and 0 indicating no revascularization. The primary end point all-cause mortality, tracked via the Office of National Statistics. A total of 660 patients were included (66 ± 10.7 years), with 43 deaths (6.5%) occurring during 2.6 ± 1.1 years after PCI. All-cause mortality was directly related to BCIS-JS(PRE) (hazard ratio [HR] 2.96, 95% confidence interval [CI] 1.71 to 5.15, p = 0.001) and BCIS-JS(POST) (HR 4.02, 95% CI 2.41 to 6.68, p = 0.001). A RI of <0.67 was associated with increased mortality compared to a RI of ≥0.67 (HR 4.13, 95% CI 1.91 to 8.91, p = 0.0001). On multivariate analysis, a RI <0.67 (HR 1.99, 95% CI 1.03 to 3.87, p = 0.04), left ventricular dysfunction (HR 2.03, 95% CI 1.25 to 3.30, p = 0.004) and renal impairment (HR 3.75, 95% CI 1.48 to 8.64, p = 0.005) were independent predictors of mortality. In conclusion, the BCIS-JS predicts mortality after PCI and can assess the degree of revascularization, with more complete revascularization conferring a survival advantage in the medium term.

Validation of the BCIS-1 myocardial jeopardy score using cardiac magnetic resonance perfusion imaging

The recently described angiographic BCIS-1 Myocardial Jeopardy Score (BCIS-JS) provides a semi-quantitative estimate of the extent of coronary artery disease (CAD). It is simple to use and applicable to all patients including those with bypass grafts. Our objective was to validate the BCIS-JS by evaluating its correlation with myocardial ischaemic burden and its accuracy at predicting a prognostic ischaemic threshold. Seventy-five patients with angina and known or suspected CAD referred for coronary angiography prospectively underwent high-resolution CMR perfusion imaging. There was good correlation between the BCIS-JS and myocardial ischaemic burden: r = 0·75, P<0·0001. Area under the ROC curve for BCIS-JS to detect ≥12% myocardial ischaemic burden was 0·87 (95% CI 0·78-0·96). BCIS-JS ≥6 predicted ≥12% myocardial ischaemic burden with a sensitivity of 68% and a specificity of 91%. The BCIS-JS correlates well with myocardial ischaemic burden. A BCIS-JS ≥6 predicts the prognostically important ischaemic threshold of 12% with high specificity. These findings demonstrate that the BCIS-JS has functional relevance and support its utility for classification of CAD burden in clinical trials and in clinical practice.

Validation of dynamic 3-dimensional whole heart magnetic resonance myocardial perfusion imaging against fractional flow reserve for the detection of significant coronary artery disease

OBJECTIVES

The goal of this study was to determine the diagnostic accuracy of dynamic 3-dimensional (3D) whole heart myocardial perfusion cardiovascular magnetic resonance (CMR) against invasively determined fractional flow reserve (FFR) and to establish the correlation between myocardium at risk defined by using the invasive Duke Jeopardy Score (DJS) and noninvasive 3D whole heart myocardial perfusion CMR.

BACKGROUND

3D whole heart myocardial perfusion CMR overcomes the limited spatial coverage of conventional two-dimensional perfusion CMR methods and allows estimation of the extent of ischemia. The method has shown good diagnostic accuracy for the detection of coronary artery disease (CAD) as defined by using quantitative coronary angiography. However, quantitative coronary angiography does not provide a functional assessment of CAD as available from pressure wire-derived FFR. In the catheter laboratory, the DJS can complement FFR to estimate the myocardium at risk.

METHODS

Fifty-three patients referred for angiography underwent rest and adenosine stress 3D whole heart myocardial perfusion CMR at 3-T. Perfusion was scored visually on a patient and coronary territory basis, and ischemic burden was calculated by quantitative segmentation of the volume of hypoenhancement. FFR was measured in vessels with ≥50% severity stenosis and an FFR <0.75 considered as hemodynamically significant. The DJS was calculated from the coronary angiograms to quantify the myocardium at risk.

RESULTS

FFR was measured in 64 of 159 coronary vessels, and 39 had an FFR <0.75. Sensitivity, specificity, and diagnostic accuracy of CMR for the detection of significant CAD were 91%, 90%, and 91%, on a patient basis and 79%, 92%, and 88%, respectively, by coronary territory. There was a strong correlation between the DJS and ischemic burden on CMR (p < 0.0001; Pearson's r = 0.82).

CONCLUSIONS

3D whole heart myocardial perfusion CMR accurately detects functionally significant CAD as defined by using FFR and provides an assessment of ischemic burden in agreement with the invasive DJS. The accurate detection of significant CAD combined with an estimation of ischemic burden by using 3D myocardial perfusion CMR holds promise for noninvasive guidance of therapy and risk stratification of patients with CAD.