Coronary microvascular reactivity to adenosine predicts adverse outcome in women evaluated for suspected ischemia results from the National Heart, Lung and Blood Institute WISE (Women's Ischemia Syndrome Evaluation) study

Etiopathogenesis of microvascular angina: caveats in our knowledge

Nearly 50% of subjects of coronary artery disease suffer from coronary microvascular dysfunction. Various etiopathogenetic factors have been proposed by different workers but no hypothesis can explain the genesis of microvascular angina in all patients. We have made an attempt to review the literature to find caveats in our knowledge so that future studies can be better designed.

Epidemiology, risk factors and management of cardiovascular diseases in IBD

IBD is an established risk factor for venous thromboembolism. In the past few years, studies have suggested that patients with IBD might also be at an increased risk of coronary heart disease and stroke. The increased risk is thought to be similar to the level of risk seen in patients with other chronic systemic inflammatory diseases such as rheumatoid arthritis. The risk of developing these conditions is particularly increased in young adults with IBD, and more so in women than in men. Conventional cardiovascular risk factors are not over-represented in patients with IBD, so the increased risk could be attributable to inflammation-mediated atherosclerosis. Patients with IBD often have premature atherosclerosis and have biochemical and genetic markers similar to those seen in patients with atherosclerotic cardiovascular disease. The role of chronic inflammation in IBD-associated cardiovascular disease merits further evaluation. Particular attention should be given to the increased risk observed during periods of increased disease activity and potential modification of the risk by immunosuppressive and biologic therapies for IBD that can modify the disease activity. In addition, preclinical studies suggest that cardiovascular medications such as statins and angiotensin-converting enzyme inhibitors might also favourably modify IBD disease activity, which warrants further evaluation.

Role of echocardiography in the management of cardiac disease in women

The widespread use of echocardiography has contributed to the early recognition of several distinct cardiac diseases in women. During pregnancy, safe monitoring of the disease process, as well as a better understanding of hemodynamics, is possible. During the use of potentially cardiotoxic drugs for breast cancer chemotherapy, echocardiographic patient monitoring is vital. Compared to men, the addition of an imaging modality to routine electrocardiogram monitoring during stress testing is more informative for diagnosing coronary disease in women. This review briefly discusses the role of echocardiography in the management of several women-specific cardiac diseases where echocardiography plays a pivotal role in disease management.

Coronary flow reserve estimated by positron emission tomography to diagnose significant coronary artery disease and predict cardiac events

Coronary artery disease (CAD) is a major cause of death in Japan. Coronary angiography is useful to assess the atherosclerotic burden in CAD patients, but its ability to predict whether patients will respond favorably to optimal medical therapy and revascularization is limited. The measurement of the fractional flow reserve with angiography is a well-validated method for identifying ischemic vessels. However, neither an anatomical assessment nor a functional assessment can delineate microvasculature or estimate its function. The quantitative coronary flow reserve (CFR) estimated from sequential myocardial perfusion images obtained by positron emission tomography (PET) during stress provides an accurate index of hyperemic reactivity to vasodilatory agents in the myocardium. In fact, there is growing evidence that the CFR reflects disease activity in the entire coronary circulation, including epicardial coronary artery stenosis, diffuse atherosclerosis, and microvascular dilatory function. Importantly, reduced CFR is observed even in patients without flow-limiting coronary stenosis, and its evaluation can improve the risk stratification of patients at any stage of CAD. This review focuses on the application of CFR estimated by cardiac PET for the diagnosis and risk stratification of patients with CAD.

Current Diagnostic and Therapeutic Strategies in Microvascular Angina

Microvascular angina is common among patients with signs and symptoms of acute coronary syndrome and is associated with an increased risk of cardiovascular and cerebrovascular events. Unfortunately, microvascular is often under-recognized in clinical settings. The diagnosis of microvascular angina relies on assessment of the functional status of the coronary microvasculature. Invasive strategies include acetylcholine provocation, intracoronary Doppler ultrasound, and intracoronary thermodilution; noninvasive strategies include cardiac positron emission tomography (PET), cardiac magnetic resonance, and Doppler echocardiography. Once the diagnosis of microvascular angina is established, treatment is focused on improving symptoms and reducing future risk of cardiovascular and cerebrovascular events. Pharmacologic options and lifestyle modifications for patients with microvascular angina are similar to those for patients with coronary artery disease.

Impact of smoking on coronary microcirculatory resistance in patients with coronary artery disease

The aim of this study was to investigate the relationship between coronary microvascular function and smoking using the 3 parameters fractional flow reserve (FFR), coronary flow reserve (CFR(thermo)), and index of microcirculatory resistance (IMR) in patients with coronary artery disease (CAD). A total of 97 CAD patients with 148 intermediate stenotic lesions were divided into two groups: current and former smokers (Smokers: n = 54), and those who had never smoked (Non-smokers: n = 43). Coronary physiology measurements were made following coronary angiography at rest and during hyperemia induced with intravenous adenosine triphosphate. If a patient had several intermediate lesions, the lesion producing the largest IMR value and minimum FFR(myo) and CFR(thermo) value was selected. Averaged over all patients, the FFR(myo), CFR(thermo), and IMR values were 0.86 ± 0.10, 2.66 ± 1.50, and 20.8 ± 10.7, respectively. There was no significant correlation between FFR(myo) and IMR. There were no significant differences between smokers and non-smokers in FFR(myo) value (median: 0.85 [IQR: 0.74-0.90] versus 0.87 [IQR: 0.83-0.90], P = 0.15) and CFR(thermo) value (median: 1.90 [IQR: 1.56-3.16] versus 2.10 [IQR: 1.50-2.67] U, P = 0.95). The IMR value was significantly greater in smokers (median: 24.2 [IQR: 16.8-32.5] U versus 18.5 [IQR: 15.4-27.0] U, P = 0.04). In multivariate analysis, smoking was an independent predictor of increased IMR. Smoking appears to have a detrimental effect on coronary microvascular function as measured by IMR.

Microvascular coronary dysfunction and ischemic heart disease: where are we in 2014?

Many patients with angina and signs of myocardial ischemia on stress testing have no significant obstructive epicardial coronary disease. There are many potential coronary and non-coronary mechanisms for ischemia without obstructive epicardial coronary disease, and prominent among these is coronary microvascular and/or endothelial dysfunction. Patients with coronary microvascular and/or endothelial dysfunction are often at increased risk of adverse cardiovascular events, including ischemic events and heart failure despite preserved ventricular systolic function. In this article, we will review the diagnosis and treatment of coronary microvascular and endothelial dysfunction, discuss their potential contribution to heart failure with preserved ejection fraction, and highlight recent advances in the evaluation of atherosclerotic morphology in these patients, many of whom have non-obstructive epicardial disease.

Associations between retinal microvascular structure and the severity and extent of coronary artery disease

OBJECTIVE

Microvascular mechanisms are increasingly recognized as being involved in a significant proportion of coronary artery disease (CAD) cases, but their exact contribution or role is unclear. We aimed to define the association between retinal microvascular signs and both CAD extent and severity.

METHODS

1120 participants of the Australian Heart Eye Study were included. Retinal vessel caliber was measured from digital retinal images. Extent and severity of CAD was assessed using several approaches. First, a simple scoring classifying participants as having one-vessel, two-vessel, and three-vessel disease was used. Gensini and Extent scores were calculated using angiography findings.

RESULTS

After multivariable adjustment, significantly narrower retinal arteriolar caliber in women (comparing lowest versus highest quartile or reference) and wider venular caliber in men (comparing highest versus lowest quartile or reference) were associated with 2-fold and 54% higher odds of having at least one stenosis ≥50% in the epicardial coronary arteries, respectively. Women in the third versus first tertile of retinal venular caliber had 92% and ∼2-fold higher likelihood of having higher Gensini and Extent scores, respectively. Women in the lowest versus highest tertile of retinal arteriolar caliber had greater odds of having higher Extent scores, OR 2.99 (95% CI 1.45-6.16). In men, non-significant associations were observed between retinal vascular caliber and Gensini and Extent scores.

CONCLUSIONS

An unhealthy retinal microvascular profile, namely, narrower retinal arterioles and wider venules was associated with more diffuse and severe CAD among women.

Coronary microvascular dysfunction in women: an overview of diagnostic strategies

Coronary microvascular dysfunction (CMD) also known as syndrome X, is characterized by typical anginal symptoms, evidence of myocardial ischemia on non-invasive testing and normal to minimal coronary disease on coronary angiography. It has a female preponderance and has been detected in up to 50% of women presenting with chest pain symptoms. Definitive diagnosis of CMD is critical as recent evidence suggests that women with this condition are at increased risk of cardiovascular events in the future. Invasive coronary reactivity testing on coronary angiography is considered to be the 'gold standard' for diagnosis of CMD. Non-invasive imaging techniques such as PET and cardiac magnetic resonance hold promise for detection of CMD in the future.

Aldosterone inhibition and coronary endothelial function in women without obstructive coronary artery disease: an ancillary study of the national heart, lung, and blood institute-sponsored women's ischemia syndrome evaluation

Endothelial dysfunction is highly prevalent and associated with adverse outcomes among patients without obstructive coronary artery disease (CAD). Angiotensin II inhibition may improve endothelial function, but with continued treatment, "aldosterone escape" may occur. Thus, it is unknown if adding aldosterone blockade further improves endothelial function.

METHODS

In a double-blind, parallel-group, repeated-measures study, women with symptoms and signs of ischemia, no significant CAD, and coronary endothelial dysfunction receiving an angiotensin-converting enzyme inhibitor or receptor blocker were randomized to aldosterone blockade or placebo. The primary outcome at 16 weeks was percent change in coronary diameter to acetylcholine, and secondary outcome, coronary flow reserve to adenosine, both adjusted for baseline reactivity.

RESULTS

Forty-one women completed the treatment period with repeat coronary reactivity testing. Their mean age was 54 ± 10 years; body mass index, 30 ± 7.4 kg/m2; 12% had diabetes; and 15% had metabolic syndrome. There were no significant differences between treatment groups. At baseline, the percent change in reference vessel coronary diameter to acetylcholine was -5.0% in the aldosterone blockade group and -3.4% in the placebo group and, at 16 weeks, -7.2% in the aldosterone blockade group versus -14.3% in the placebo group (P = .15). At 16 weeks, the change in coronary flow reserve to intracoronary adenosine was -0.13 in the aldosterone blockade group versus -0.25 in the placebo group (P = .66).

CONCLUSION

Adding aldosterone receptor blockade to angiotensin II inhibition did not improve coronary endothelial or microvascular function among women with signs and symptoms of ischemia in the setting of nonobstructive CAD.

Effects of angiotensin-converting enzyme inhibitors and beta blockers on clinical outcomes in patients with and without coronary artery obstructions at angiography (from a Register-Based Cohort Study on Acute Coronary Syndromes)

We sought to determine the effectiveness of angiotensin-converting enzyme (ACE) inhibition and β-blocker treatment as a function of the degree of coronary artery disease (CAD) obstruction at angiography. The Evaluation of Methods and Management of Acute Coronary Events registry enrolled patients who had been hospitalized for an acute coronary syndrome. There were 1,602 patients who had cardiac catheterization that were used for this analysis. The main outcome measures were evidence-based therapies prescribed at discharge and 6-month incidence of all-cause mortality. The cohort consisted of 1,252 patients with obstructive CAD (>50% luminal diameter obstructed) and 350 patients with nonobstructive CAD. Multivariate logistic regression analysis adjusted for further medications and other clinical factors was performed. Patients with nonobstructive CAD had significantly (p <0.001) higher rates of β-blocker (77.8% vs 63.3%) and lower rates of ACE-inhibitor (57.7% vs 66.4%) prescriptions. In patients with nonobstructive CAD, ACE-inhibitor therapy was clearly associated with a lower 6-month mortality (odds ratio [OR] 0.31, 95% confidence interval [CI] 0.03 to 0.78, p = 0.004). No significant association between β-blocker use and death was found. In patients with obstructive CAD, both β blockers (OR 0.47, 95% CI 0.32 to 0.67, p <0.001) and ACE inhibitors (OR 0.47, 95% CI 0.26 to 0.87, p = 0.01) were significantly associated with a reduced risk of 6-month mortality. In conclusion, ACE-inhibitor therapy seems to be an effective first-line treatment for preventing the occurrence of mortality in patients with nonobstructive CAD.

TIMI frame count and adverse events in women with no obstructive coronary disease: a pilot study from the NHLBI-sponsored Women's Ischemia Syndrome Evaluation (WISE)

BACKGROUND

TIMI frame count (TFC) predicts outcomes in patients with obstructive coronary artery disease (CAD); it remains unclear whether TFC predicts outcomes in patients without obstructive CAD.

METHODS

TFC was determined in a sample of women with no obstructive CAD enrolled in the Women's Ischemia Syndrome Evaluation (WISE) study. Because TFC is known to be higher in the left anterior descending artery (LAD), TFC determined in the LAD was divided by 1.7 to provide a corrected TFC (cTFC).

RESULTS

A total of 298 women, with angiograms suitable for TFC analysis and long-term (6-10 year) follow up data, were included in this sub-study. Their age was 55±11 years, most were white (86%), half had a history of smoking, and half had a history of hypertension. Higher resting cTFC was associated with a higher rate of hospitalization for angina (34% in women with a cTFC >35, 15% in women with a cTFC ≤35, P<0.001). cTFC provided independent prediction of hospitalization for angina after adjusting for many baseline characteristics. In this cohort, resting cTFC was not predictive of major events (myocardial infarction, heart failure, stroke, or all-cause death), cardiovascular events, all-cause mortality, or cardiovascular mortality.

CONCLUSIONS

In women with signs and symptoms of ischemia but no obstructive CAD, resting cTFC provides independent prediction of hospitalization for angina. Larger studies are required to determine if resting TFC is predictive of major events in patients without obstructive coronary artery disease.

Diastolic dysfunction in women with signs and symptoms of ischemia in the absence of obstructive coronary artery disease: a hypothesis-generating study

BACKGROUND

Angina, in the absence of obstructive coronary artery disease, is more common in women, is associated with adverse cardiovascular morbidity and mortality, and is a major burden to the healthcare system. Although advancements have been made to understand the mechanistic underpinning of this disease, the functional consequence remains unclear.

METHODS AND RESULTS

Cardiac magnetic resonance imaging was performed to assess left ventricular function in 20 women with signs and symptoms of ischemia, but no obstructive coronary artery disease (cases), and 15 age- and body mass index-matched reference controls. Functional imaging included standard cinematic imaging to assess left ventricular morphology and global function, along with tissue tagging to assess left ventricular tissue deformation. Systolic function was preserved in both cases and controls, with no differences in ejection fraction (mean±SE: 63.1±8% versus 65±2%), circumferential strain (-20.7±0.6% versus -21.9±0.5%), or systolic circumferential strain rate (-105.9±6.1% versus -109.0±3.8% per second). In contrast, we observed significant differences between cases and controls in diastolic function, as demonstrated by reductions in both diastolic circumferential strain rate (153.8±8.9% versus 191.4±8.9% per second; P<0.05) and peak rate of left ventricular untwisting (-99.4±8.0° versus -129.4±12.8° per second; P<0.05).

CONCLUSIONS

Diastolic function is impaired in women with signs and symptoms of ischemia in the absence of coronary artery disease, as assessed by cardiac magnetic resonance tissue tagging. These results are hypothesis-generating. Larger studies are needed to define the exact mechanism(s) responsible and to establish viable treatment strategies.

Effects of sex on coronary microvascular dysfunction and cardiac outcomes

BACKGROUND

Coronary microvascular dysfunction (CMD) is a prevalent and prognostically important finding in patients with symptoms suggestive of coronary artery disease. The relative extent to which CMD affects both sexes is largely unknown.

METHODS AND RESULTS

We investigated 405 men and 813 women who were referred for evaluation of suspected coronary artery disease with no previous history of coronary artery disease and no visual evidence of coronary artery disease on rest/stress positron emission tomography myocardial perfusion imaging. Coronary flow reserve was quantified, and coronary flow reserve <2.0 was used to define the presence of CMD. Major adverse cardiac events, including cardiac death, nonfatal myocardial infarction, late revascularization, and hospitalization for heart failure, were assessed in a blinded fashion over a median follow-up of 1.3 years (interquartile range, 0.5-2.3 years). CMD was highly prevalent both in men and women (51% and 54%, respectively; Fisher exact test =0.39; equivalence P=0.0002). Regardless of sex, coronary flow reserve was a powerful incremental predictor of major adverse cardiac events (hazard ratio, 0.80 [95% confidence interval, 0.75-086] per 10% increase in coronary flow reserve; P<0.0001) and resulted in favorable net reclassification improvement (0.280 [95% confidence interval, 0.049-0.512]), after adjustment for clinical risk and ventricular function. In a subgroup (n=404; 307 women/97 men) without evidence of coronary artery calcification on gated computed tomography imaging, CMD was common in both sexes, despite normal stress perfusion imaging and no coronary artery calcification (44% of men versus 48% of women; Fisher exact test P=0.56; equivalence P=0.041).

CONCLUSIONS

CMD is highly prevalent among at-risk individuals and is associated with adverse outcomes regardless of sex. The high prevalence of CMD in both sexes suggests that it may be a useful target for future therapeutic interventions.

Physiological basis and long-term clinical outcome of discordance between fractional flow reserve and coronary flow velocity reserve in coronary stenoses of intermediate severity

BACKGROUND

Discordance between fractional flow reserve (FFR) and coronary flow velocity reserve (CFVR) may reflect important coronary pathophysiology but usually remains unnoticed in clinical practice. We evaluated the physiological basis and clinical outcome associated with FFR/CFVR discordance.

METHODS AND RESULTS

We studied 157 intermediate coronary stenoses in 157 patients, evaluated by FFR and CFVR between April 1997 and September 2006 in which revascularization was deferred. Long-term follow-up was performed to document the occurrence of major adverse cardiac events: cardiac death, myocardial infarction, or target vessel revascularization. Discordance between FFR and CFVR occurred in 31% and 37% of stenoses at the 0.75, and 0.80 FFR cut-off value, respectively, and was characterized by microvascular resistances during basal and hyperemic conditions. Follow-up duration amounted to 11.7 years (Q1-Q3, 9.9-13.3 years). Compared with concordant normal results of FFR and CFVR, a normal FFR with an abnormal CFVR was associated with significantly increased major adverse cardiac events rate throughout 10 years of follow-up, regardless of the FFR cut-off applied. In contrast, an abnormal FFR with a normal CFVR was associated with equivalent clinical outcome compared with concordant normal results: ≤ 3 years when FFR <0.75 was depicted abnormal and throughout 10 years of follow-up when FFR ≤ 0.80 was depicted abnormal.

CONCLUSIONS

Discordance of CFVR with FFR originates from the involvement of the coronary microvasculature. Importantly, the risk for major adverse cardiac events associated with FFR/CFVR discordance is mainly attributable to stenoses where CFVR is abnormal. This emphasizes the requirement of intracoronary flow assessment in addition to coronary pressure for optimal risk stratification in stable coronary artery disease.

The relationship between endothelial progenitor cell populations and epicardial and microvascular coronary disease-a cellular, angiographic and physiologic study

BACKGROUND

Endothelial progenitor cells (EPCs) are implicated in protection against vascular disease. However, studies using angiography alone have reported conflicting results when relating EPCs to epicardial coronary artery disease (CAD) severity. Moreover, the relationship between different EPC types and the coronary microcirculation is unknown. We therefore investigated the relationship between EPC populations and coronary epicardial and microvascular disease.

METHODS

Thirty-three patients with a spectrum of isolated left anterior descending artery disease were studied. The coronary epicardial and microcirculation were physiologically interrogated by measurement of fractional flow reserve (FFR), index of microvascular resistance (IMR) and coronary flow reserve (CFR). Two distinct EPC populations (early EPC and late outgrowth endothelial cells [OECs]) were isolated from these patients and studied ex vivo.

RESULTS

There was a significant inverse relationship between circulating OEC levels and epicardial CAD severity, as assessed by FFR and angiography (r=0.371, p=0.04; r=-0.358, p=0.04; respectively). More severe epicardial CAD was associated with impaired OEC migration and tubulogenesis (r=0.59, p=0.005; r=0.589, p=0.004; respectively). Patients with significant epicardial CAD (FFR<0.75) had lower OEC levels and function compared to those without hemodynamically significant stenoses (p<0.05). In contrast, no such relationship was seen for early EPC number and function, nor was there a relationship between IMR and EPCs. There was a significant relationship between CFR and OEC function.

CONCLUSIONS

EPC populations differ in regards to their associations with CAD severity. The number and function of OECs, but not early EPCs, correlated significantly with epicardial CAD severity. There was no relationship between EPCs and severity of coronary microvascular disease.

Burden of hospital admission and repeat angiography in angina pectoris patients with and without coronary artery disease: a registry-based cohort study

AIMS

To evaluate risk of hospitalization due to cardiovascular disease (CVD) and repeat coronary angiography (CAG) in stable angina pectoris (SAP) with no obstructive coronary artery disease (CAD) versus obstructive CAD, and asymptomatic reference individuals.

METHODS AND RESULTS

We followed 11,223 patients with no prior CVD having a first-time CAG in 1998-2009 due to SAP symptoms and 5,695 asymptomatic reference individuals from the Copenhagen City Heart Study through registry linkage for 7.8 years (median). In recurrent event survival analysis, patients with SAP had 3-4-fold higher risk of hospitalization for CVD irrespective of CAG findings and cardiovascular comorbidity. Multivariable adjusted hazard ratios(95%CI) for patients with angiographically normal coronary arteries was 3.0(2.5-3.5), for angiographically diffuse non-obstructive CAD 3.9(3.3-4.6) and for 1-3-vessel disease 3.6-4.1(range)(all P<0.001). Mean accumulated hospitalization time was 3.5(3.0-4.0)(days/10 years follow-up) in reference individuals and 4.5(3.8-5.2)/7.0(5.4-8.6)/6.7(5.2-8.1)/6.1(5.2-7.4)/8.6(6.6-10.7) in patients with angiographically normal coronary arteries/angiographically diffuse non-obstructive CAD/1-, 2-, and 3-vessel disease, respectively (all P<0.05, age-adjusted). SAP symptoms predicted repeat CAG with multivariable adjusted hazard ratios for patients with angiographically normal coronary arteries being 2.3(1.9-2.9), for angiographically diffuse non-obstructive CAD 5.5(4.4-6.8) and for obstructive CAD 6.6-9.4(range)(all P<0.001).

CONCLUSIONS

Patients with SAP symptoms and angiographically normal coronary arteries or angiographically diffuse non-obstructive CAD suffer from considerably greater CVD burdens in terms of hospitalization for CVD and repeat CAG compared with asymptomatic reference individuals even after adjustment for cardiac risk factors and exclusion of cardiovascular comorbidity as cause. Contrary to common perception, excluding obstructive CAD by CAG in such patients does not ensure a benign cardiovascular prognosis.

Improving diagnosis and treatment of women with angina pectoris and microvascular disease: the iPOWER study design and rationale

BACKGROUND

The iPOWER study aims at determining whether routine assessment of coronary microvascular dysfunction (CMD) in women with angina and no obstructive coronary artery disease is feasible and identifies women at risk.

METHODS

All women with angina referred to invasive angiographic assessment in Eastern Denmark are invited to join the study according to in- and exclusion criteria. Assessment includes demographic, clinical and psychosocial data, symptoms, electrocardiogram, blood- and urine samples and transthoracic echocardiography during rest and dipyridamol stress with measurement of coronary flow reserve (CFR) by Doppler of the left anterior descending artery. In substudies CMD will be assessed by positron emission tomography, peripheral endothelial function, magnetic resonance imaging-and computed tomography derived myocardial perfusion scans, angiographic corrected TIMI frame counts, advanced echocardiographic modalities at rest and during stress, and invasive measures of CFR and coronary vascular reactivity. The study will include 2000 women who will be followed for 5 years for cardiovascular outcomes.

RESULTS

By May 2013, 1685 women have been screened, 759 eligible patients identified, 530 contacted, and 299 (56%) agreed to participate. Among the first 50 patients, Doppler CFR was successfully measured in 49 (98%).

CONCLUSIONS

Among women with suspected ischemic heart disease and no obstructive coronary artery disease, non-invasive Doppler CFR is feasible as a routine assessment. The study will provide information on methods to diagnose CMD and determine the prognostic value of routine non-invasive assessment of microvascular function. Future study will provide women identified with CMD participation in interventional substudies designed to test treatment strategies.

Systemic inflammation is related to coronary microvascular dysfunction in obese patients without obstructive coronary disease

BACKGROUND AND AIMS

Obesity, systemic inflammation and changes in the heart functions are associated with increased cardiovascular risk. This study aimed to investigate coronary microvascular dysfunction as an early marker of atherosclerosis in obese patients without any evidence of cardiovascular disease.

METHODS AND RESULTS

86 obese subjects (aged 44 ± 12 years, body mass index (BMI) 41 ± 8 kg m(-2)), without evidence of heart disease, and 48 lean controls were studied using transthoracic Doppler echocardiography for detecting coronary flow reserve (CFR). A value of CFR ≤ 2.5 was considered abnormal. We measured interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α) and adiponectin in all patients. Patients with abnormal CFR underwent coronary multislice computed tomography (MSCT) in order to exclude an epicardial stenosis. CFR in obese subjects was lower than in lean subjects (3.2 ± 0.8 vs. 3.7 ± 0.7, p = 0.02) and was abnormal in 27 (31%) obese patients and in one (2%) control (p < 0.0001). All subjects with abnormal CFR showed no coronary stenosis at MSCT. At multivariable analysis, IL-6 and TNF-α were the only determinants of CFR (p < 0.02 and p < 0.02, respectively). At multivariable logistic regression analysis, IL-6 and TNF-α were the only determinants of CFR ≤ 2.5 (p < 0.03 and p < 0.03, respectively).

CONCLUSIONS

CFR is often reduced in obese subjects without clinical evidence of heart disease, suggesting a coronary microvascular impairment. This microvascular dysfunction seems to be related to a chronic inflammation mediated by adipocytokines. Our findings may explain the increased cardiovascular risk in obesity, independently of BMI.

New insights from major prospective cohort studies with cardiac nuclear imaging

For more than two decades, radionuclide imaging has prevailed as a cornerstone in the diagnosis and treatment of patients with cardiac disease. From this experience, large cohort studies have emerged that demonstrate the prognostic value of cardiac radionuclide imaging in a variety of patient groups and conditions. Myocardial perfusion imaging has accrued the most robust evidence for accurate and independent risk stratification over traditional clinical variables. In a variety of patient populations, the presence of myocardial ischemia is a strong predictor of cardiac events on follow-up. In patients with heart failure, smaller observations have similarly established the prognostic value of viability imaging and imaging of cardiac sympathetic activity. The present review provides a summary of recent cohort studies with radionuclide imaging and a critical appraisal of their clinical implications. Its purpose is to put the available evidence into a clinical context, analyze its potential impact on patient management and identify gaps in knowledge and unanswered questions to be addressed in future randomized trials.

Management of microvascular angina pectoris

Microvascular angina (MVA) is defined as angina pectoris caused by abnormalities of small coronary arteries. In its most typical presentation, MVA is characterized by angina attacks mainly caused by effort, evidence of myocardial ischemia on non-invasive stress tests, but normal coronary arteries at angiography. Patients with stable MVA have excellent long-term prognoses, but often present with persistent and/or worsening of angina symptoms. Treatment of MVA is initially based on standard anti-ischemic drugs (beta-blockers, calcium antagonists, and nitrates), but control of symptoms is often insufficient. In these cases, several additional drugs, with different potential anti-ischemic effects, have been proposed, including ranolazine, ivabradine, angiotensin-converting enzyme (ACE) inhibitors, xanthine derivatives, nicorandil, statins, alpha-blockers and, in perimenopausal women, estrogens. In patients with 'refractory MVA', some further alternative therapies (e.g., spinal cord stimulation, pain-inhibiting substances such as imipramine, rehabilitation programs) have shown favorable results.

A case of vasospastic angina in which the ergonovine provocation test with intracoronary isosorbide dinitrate and nicorandil was effective in the diagnosis of microvascular spasm

A 60-year-old man was admitted with early morning angina while at rest. Coronary angiogram revealed no organic lesions; therefore, a spasm provocation test with ergonovine was performed. Administration of intracoronary ergonovine induced total occlusion of the right coronary artery. The induced total occlusion improved but coronary flow velocity remained severely reduced and chest discomfort with ST-T changes in ECG remained in spite of repeated administration of isosorbide dinitrate (ISDN). Intracoronary administration of nicorandil following ISDN alleviated the chest discomfort, normalized the ST-T change in ECG, and improved the coronary flow. This suggested that microvascular spasm and the epicardial spasm were not relieved by ISDN but by nicorandil. Intracoronary nicorandil injection following ISDN administration may be useful for the diagnosis of microvascular spasm in the ergonovine provocation test.

Coronary microvascular dysfunction: an update

Many patients undergoing coronary angiography because of chest pain syndromes, believed to be indicative of obstructive atherosclerosis of the epicardial coronary arteries, are found to have normal angiograms. In the past two decades, a number of studies have reported that abnormalities in the function and structure of the coronary microcirculation may occur in patients without obstructive atherosclerosis, but with risk factors or with myocardial diseases as well as in patients with obstructive atherosclerosis; furthermore, coronary microvascular dysfunction (CMD) can be iatrogenic. In some instances, CMD represents an epiphenomenon, whereas in others it is an important marker of risk or may even contribute to the pathogenesis of cardiovascular and myocardial diseases, thus becoming a therapeutic target. This review article provides an update on the clinical relevance of CMD in different clinical settings and also the implications for therapy.

Coronary flow reserve predicts cardiopulmonary fitness in patients with coronary artery disease independently of systolic and diastolic function

AIMS

Despite revascularization and optimal medical treatment, patients with coronary artery disease (CAD) have reduced exercise capacity. In the absence of coronary artery stenosis, coronary flow reserve (CFR) is a measure of coronary microvascular function, and a marker of future poor outcome in CAD patients. The aim of this study was to examine the relationship among CFR, systolic and diastolic function, peripheral vascular function, and cardiopulmonary fitness in CAD patients.

METHODS AND RESULTS

Forty patients with median left ventricular ejection fraction (LVEF) 49 (interquartile 46-55) with documented CAD without significant left anterior descending artery (LAD) stenosis underwent cardiorespiratory exercise test with measurement of VO2 peak, digital measurement of endothelial function and arterial stiffness, and an echocardiography with measurement of LVEF using the biplane Simpson model, mitral early (E) and late (A) inflow velocities, and tissue Doppler diastolic (e') and systolic (s') velocities. Peak coronary flow velocity (CFV) was measured in the LAD using pulse-wave Doppler. CFR was calculated as the ratio between peak CFV at rest and during vasodilator stress. Median CFR was 2.22 (1.90-2.62) and VO2 peak was 21.8 (17.6-25.5). VO2 peak correlated significantly with CFR (r = 0.57, P < 0.001), E/e' (r = -0.35, P = 0.04), and s' (r = 0.41, P = 0.01) and with LVEF (r = 0.35, P = 0.03). CFR remained independently associated with VO2 peak after adjustment for systolic and diastolic function.

CONCLUSIONS

Coronary flow reserve measured noninvasively predicts cardiopulmonary fitness independently of resting systolic and diastolic function in CAD patients, indicating that cardiac output during maximal exercise is dependent on the ability of the coronary circulation to adapt to the higher metabolic demands of the myocardium.

Number and function of bone-marrow derived angiogenic cells and coronary flow reserve in women without obstructive coronary artery disease: a substudy of the NHLBI-sponsored Women's Ischemia Syndrome Evaluation (WISE)

BACKGROUND

In women with ischemia and no obstructive coronary artery disease, the Women's Ischemic Syndrome Evaluation (WISE) observed that microvascular coronary dysfunction (MCD) is the best independent predictor of adverse cardiovascular events. Since coronary microvascular tone is regulated in part by endothelium, we hypothesized that circulating endothelial cells (CEC), which reflect endothelial injury, and the number and function of bone-marrow derived angiogenic cells (BMDAC), which could help repair damaged endothelium, may serve as biomarkers for decreased coronary flow reserve (CFR) and MCD.

METHODS

We studied 32 women from the WISE cohort. CFR measurements in response to intracoronary adenosine were taken as an index of MCD. We enumerated BMDAC colonies and CEC in peripheral blood samples. BMDAC function was assessed by assay of migration of CD34+ cells toward SDF-1 and measurement of bioavailable nitric oxide (NO). These findings were compared with a healthy reference group and also entered into a multivariable model with CFR as the dependent variable.

RESULTS

Compared with a healthy reference group, women with MCD had lower numbers of BMDAC colonies [16 (0, 81) vs. 24 (14, 88); P = 0.01] and NO [936 (156, 1875) vs. 1168 (668, 1823); P = 0.02]. Multivariable regression analysis showed strong correlation of CFR to the combination of BMDAC colony count and CD34+ cell function (migration and NO) (R(2) = 0.45; P<0.05).

CONCLUSIONS

The BMDAC function and numbers of BMDAC colonies are decreased in symptomatic women with MCD and are independently associated with CFR. These circulating cells may provide mechanistic insights into MCD in women with ischemia.

Sex-related differences in fractional flow reserve-guided treatment

BACKGROUND

Sex-specific differences affect the evaluation, treatment, and prognosis of coronary artery disease. We tested the hypothesis that long-term outcomes of fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) are different between women and men.

METHODS AND RESULTS

Consecutive 1090 patients, referred for PCI and undergoing FFR measurements at the Mayo Clinic between October 2002 and December 2009, were included in this registry study. Clinical events were compared between the sexes during a median follow-up of 50.9 months. Of all patients, women had higher FFR adjusted by visual coronary stenosis than men (P=0.03). The Kaplan-Meier percent of major adverse cardiac events at 5 years was 35% in women and 38% in men (P=0.54). Interestingly, in patients undergoing PCI with an FFR <0.75, the incidence of death or myocardial infarction was significantly higher in women than in men (hazard ratio, 2.16; 95% confidence interval, 1.04-4.51; P=0.04). Moreover, compared with patients with FFR >0.80, deferral of PCI for those with FFR between 0.75 and 0.80 was associated with an increased rate of major adverse cardiac events, particularly death or myocardial infarction in women (hazard ratio, 3.25; 95% confidence interval, 1.56-6.74; P=0.002) and revascularization in men (hazard ratio, 2.66; 95% confidence interval, 1.66-4.54; P<0.001).

CONCLUSIONS

Long-term outcome differs between women and men undergoing FFR-guided PCI. Our data suggest that the sex-based treatment strategy is necessary to further optimize prognosis of patients with coronary artery disease.

Disturbed coronary hemodynamics in vessels with intermediate stenoses evaluated with fractional flow reserve: a combined analysis of epicardial and microcirculatory involvement in ischemic heart disease

BACKGROUND

In chronic ischemic heart disease, focal stenosis, diffuse atherosclerotic narrowings, and microcirculatory dysfunction (MCD) contribute to limit myocardial flow. The prevalence of these ischemic heart disease levels in fractional flow reserve (FFR) interrogated vessels remains largely unknown.

METHODS AND RESULTS

Using intracoronary measurements, 91 coronaries (78 patients) with intermediate stenoses were classified in 4 FFR and coronary flow reserve (CFR) agreement groups, using FFR>0.80 and CFR<2 as cutoffs. Index of microcirculatory resistance (IMR) and atherosclerotic burden (Gensini score) were also assessed. MCD was assumed when IMR≥29.1 (75(th) percentile). Fifty-four (59.3%) vessels had normal FFR, from which only 20 (37%) presented both normal CFR and IMR. Among vessels with FFR>0.80, most (63%) presented disturbed hemodynamics: abnormal CFR in 28 (52%) and MCD in 18 (33%). Vessels with FFR>0.80 presented higher IMR [adjusted mean 27.6 (95% confidence interval, 23.4-31.8)] than those with FFR≤0.80 [17.3 (95% confidence interval, 13.0-21.7), p=0.001]. Atherosclerotic burden was inversely correlated with CFR (r=-0.207, P=0.055), and in vessels with FFR>0.80 and CFR<2 (n=28, 39%), IMR had a wide dispersion (7-72.7 U), suggesting a combination of diffuse atherosclerotic narrowings and MCD. Vessels with FFR≤0.80 and normal CFR presented the lowest IMR, suggesting a preserved microcirculation.

CONCLUSIONS

A substantial number of coronary arteries with stenoses showing an FFR>0.80 present disturbed hemodynamics. Integration of FFR, CFR, and IMR supports the existence of differentiated patterns of ischemic heart disease that combine focal and diffuse coronary narrowings with variable degrees of MCD.

Sex is associated with the presence of atherosclerotic plaque hemorrhage and modifies the relation between plaque hemorrhage and cardiovascular outcome

BACKGROUND AND PURPOSE

Plaque hemorrhage (PH) may lead to accelerated progression of atherosclerotic disease. The presence of local PH in the carotid plaque predicts future cardiovascular events in any vascular territory. We investigated the prevalence of local PH and the predictive value of PH for the occurrence of cardiovascular events in men and women separately.

METHODS

Atherosclerotic plaques from 1422 patients (969 men, 453 women) who underwent carotid endarterectomy were analyzed histologically for the presence of PH. Patients were monitored for 3 years for cardiovascular events (nonfatal stroke, nonfatal myocardial infarction, vascular death, and vascular intervention).

RESULTS

Plaques from men showed a significantly higher prevalence of PH compared with women (67% versus 54%; P<0.001). In 1353 patients with available follow-up data, with a median duration of 2.9 years, 270 events had occurred in men (29%) and 94 in women (22%). Stratified by presence of PH, the event rate was 32% in men with PH versus 23% in men without PH, and 23% in women with PH versus 21% in women without PH. A multivariable Cox proportional hazards model found a significant interaction between sex and PH. PH was significantly associated with events in men (adjusted hazard ratio, 1.9; 95% CI, 1.2-2.8) but not in women (adjusted hazard ratio, 1.0; 95% CI, 0.6-1.7).

CONCLUSIONS

Atherosclerotic carotid plaques obtained from men reveal a higher prevalence of PH compared with women. Local PH is strongly related to secondary manifestations of cardiovascular disease in men but not in women.

Brachial artery constriction during brachial artery reactivity testing predicts major adverse clinical outcomes in women with suspected myocardial ischemia: results from the NHLBI-sponsored women's ischemia Syndrome Evaluation (WISE) Study

BACKGROUND

Limited brachial artery (BA) flow-mediated dilation during brachial artery reactivity testing (BART) has been linked to increased cardiovascular risk. We report on the phenomenon of BA constriction (BAC) following hyperemia.

OBJECTIVES

To determine whether BAC predicts adverse CV outcomes and/or mortality in the women's ischemic Syndrome Evaluation Study (WISE). Further, as a secondary objective we sought to determine the risk factors associated with BAC.

METHODS

We performed BART on 377 women with chest pain referred for coronary angiography and followed for a median of 9.5 years. Forearm ischemia was induced with 4 minutes occlusion by a cuff placed distal to the BA and inflated to 40mm Hg > systolic pressure. BAC was defined as >4.8% artery constriction following release of the cuff. The main outcome was major adverse events (MACE) including all-cause mortality, non-fatal MI, non-fatal stroke, or hospitalization for heart failure.

RESULTS

BA diameter change ranged from -20.6% to +44.9%, and 41 (11%) women experienced BAC. Obstructive CAD and traditional CAD risk factors were not predictive of BAC. Overall, 39% of women with BAC experienced MACE vs. 22% without BAC (p=0.004). In multivariate Cox proportional hazards regression, BAC was a significant independent predictor of MACE (p=0.018) when adjusting for obstructive CAD and traditional risk factors.

CONCLUSIONS

BAC predicts almost double the risk for major adverse events compared to patients without BAC. This risk was not accounted for by CAD or traditional risk factors. The novel risk marker of BAC requires further investigation in women.

Presentation, management, and outcomes of ischaemic heart disease in women

Scientific interest in ischaemic heart disease (IHD) in women has grown considerably over the past 2 decades. A substantial amount of the literature on this subject is centred on sex differences in clinical aspects of IHD. Many reports have documented sex-related differences in presentation, risk profiles, and outcomes among patients with IHD, particularly acute myocardial infarction. Such differences have often been attributed to inequalities between men and women in the referral and treatment of IHD, but data are insufficient to support this assessment. The determinants of sex differences in presentation are unclear, and few clues are available as to why young, premenopausal women paradoxically have a greater incidence of adverse outcomes after acute myocardial infarction than men, despite having less-severe coronary artery disease. Although differential treatment on the basis of patient sex continues to be described, the extent to which such inequalities persist and whether they reflect true disparity is unclear. Additionally, much uncertainty surrounds possible sex-related differences in response to cardiovascular therapies, partly because of a persistent lack of female-specific data from cardiovascular clinical trials. In this Review, we assess the evidence for sex-related differences in the clinical presentation, treatment, and outcome of IHD, and identify gaps in the literature that need to be addressed in future research efforts.

Cardiac risk factors and myocardial perfusion reserve in women with microvascular coronary dysfunction

Women with myocardial ischemia without obstructive coronary artery disease (CAD) often have microvascular coronary dysfunction (MCD). Traditional cardiac risk factors (RFs) contribute modestly to MCD detected by invasive coronary reactivity testing (CRT). Cardiac magnetic resonance imaging (CMRI) is an emerging noninvasive technique used to evaluate MCD. We evaluated RFs related to CMRI myocardial perfusion in women with MCD. 53 women with CRT confirmed MCD underwent adenosine stress and rest CMRI (1.5 Tesla). The myocardial perfusion reserve index (MPRI) was calculated (Pie Medical) with lower MPRI meaning less perfusion reserve. Relationships between RFs and MPRI were examined. The mean age was 54±10 years with a mean body mass index (BMI) of 26.2±4.2. The mean MPRI was 1.63±0.39. Hypertension, dyslipidemia, elevated BMI, and post-menopausal status were inversely related to MPRI, while ever smoking, age, family history of CAD, history of irregular menses, and history of menopausal hormone therapy (MHT) or oral contraceptive (OC) use were not. Dyslipidemia and BMI remained significant independent predictors of MPRI. Regression modeling demonstrated that the RFs of dyslipidemia, obesity, hypertension, family history of CAD, and history of irregular menses explained 27% of the observed MCD variance.

CONCLUSIONS

In conclusion, impaired MPRI measured by CMRI is related to dyslipidemia and elevated BMI in women with MCD. These results suggest traditional RFs contribute modestly to MCD; a larger cohort of women with MCD should be examined to confirm and extend these observations. The impact of traditional CAD RF modification strategies, including optimal medical therapy, should be explored as MCD treatment targets.

Cardiac magnetic resonance imaging myocardial perfusion reserve index assessment in women with microvascular coronary dysfunction and reference controls

OBJECTIVE

We sought to comparatively assess cardiac magnetic resonance imaging (CMRI) myocardial perfusion reserve index (MPRI) in women with confirmed microvascular coronary dysfunction (MCD) cases and reference control women.

BACKGROUND

Women with signs or symptoms of myocardial ischemia in the absence of obstructive coronary artery disease (CAD) frequently have MCD which carries an adverse prognosis. Diagnosis involves invasive coronary reactivity testing (CRT). Adenosine CMRI is a non-invasive test that may be useful for the detection of MCD.

METHODS

Fifty-three women with MCD confirmed by CRT and 12 age- and estrogen-use matched reference controls underwent adenosine CMRI. CMRI was assessed for MPRI, calculated using the ratio of myocardial blood flow at hyperemia/rest for the whole myocardium and separately for the 16 segments as defined by the American Heart Association. Statistical analysis was performed using repeated measures ANOVA models.

RESULTS

Compared to reference controls, MCD cases had lower MPRI values globally and in subendocardial and subepicardial regions (1.63±0.39 vs. 1.98±0.38, P=0.007, 1.51±0.35 vs. 1.84±0.34, P=0.0045, 1.68±0.38 vs. 2.04±0.41, P=0.005, respectively). A perfusion gradient across the myocardium with lower MPRI in the subendocardium compared to the subepicardium was observed for both groups.

CONCLUSIONS

Women with MCD have lower MPRI measured by perfusion CMRI compared to reference controls. CMRI may be a useful diagnostic modality for MCD. Prospective validation of a diagnostic threshold for MPRI in patients with MCD is needed.

Diagnosing and characterizing coronary artery disease in women: developments in noninvasive and invasive imaging techniques

Cardiovascular disease is the leading cause of death in men and women in the USA; yet, coronary artery disease (CAD) continues to be underrecognized and underdiagnosed in women. Noninvasive and invasive imaging techniques are constantly being developed in order to more accurately assess CAD. At the same time, the impact of gender on the interpretation and accuracy of these studies is still being elucidated. Furthermore, new imaging techniques have improved our understanding of CAD pathophysiology and progression and have begun to reveal gender differences in the development of CAD. This article will review current imaging techniques and their application to diagnosing and understanding CAD in women.