Ischemia With Nonobstructive Coronary Arteries: Insights From the ISCHEMIA Trial

INOCA: Ischemia in non-obstructive coronary arteries

This article provides a summary of the clinical spectrum of no obstructive coronary arteries. We describe the pathologies, invasive and noninvasive assessment, and management strategies.

Nonobstructive epicardial coronary artery disease: an evolving concept in need of diagnostic and therapeutic guidance

For decades, we have been treating patients presenting with angina and concerning electrocardiographic changes indicative of ischemia or injury, in whom no culprit epicardial coronary stenosis was found during diagnostic coronary angiography. Unfortunately, the clinical outcomes of these patients were not better than those with recognized obstructive coronary disease. Improvements in technology have allowed us to better characterize these patients. Consequently, an increasing number of patients with ischemia and no obstructive coronary artery disease (INOCA) or myocardial infarction in the absence of coronary artery disease (MINOCA) have now gained formal recognition and are more commonly encountered in clinical practice. Although both entities might share functional similarities at their core, they pose significant diagnostic and therapeutic challenges. Unless we become more proficient in identifying these patients, particularly those at higher risk, morbidity and mortality outcomes will not improve. Though this field remains in constant flux, data continue to become available. Therefore, we thought it would be useful to highlight important milestones that have been recognized so we can all learn about these clinical entities. Despite all the progress made regarding INOCA and MINOCA, many important knowledge gaps continue to exist. For the time being, prompt identification and early diagnosis remain crucial in managing these patients. Even though we are still not clear whether intensive medical therapy alters clinical outcomes, we remain vigilant and wait for more data.

Intravascular imaging in the diagnosis and management of patients with suspected intracoronary pathologies: A CJC White Paper

Intravascular imaging has become an integral part of the diagnostic and management strategies for intracoronary pathologies. This White Paper summarizes current evidence and its implications on the use of intravascular imaging in interventional cardiology practice. The areas addressed are planning and optimization of percutaneous coronary intervention, management of stent failure, and evaluation of ambiguous coronary lesions and myocardial infarction with non-obstructive coronary disease (MINOCA). Findings are presented following the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system in an expert consensus process involving a diverse Writing group and vetted by a Review group. Expert consensus was achieved around nine statements. Use of intravascular imaging in guiding percutaneous revascularization is supported by high quality evidence, particularly for lesions with increased risk of recurrent events or stent failure. Specific considerations for intravascular imaging guidance of intervention in left main lesions, chronic occlusion lesions as well as patients at high risk of contrast nephropathy are explored. Use of intravascular imaging to identify pathologies associated with stent failure and guide repeat intervention, resolve ambiguities in lesion assessment and establish diagnoses in patients presenting with MINOCA is supported by moderate to low quality evidence. Each topic is accompanied by clinical pointers to aid the practicing interventional cardiologist in implementation of the White paper findings. The findings of this White Paper will help to guide the utilization of intravascular imaging towards those situations in which the balance of efficacy, safety and cost are most optimal.

Coronary microvascular dysfunction and cancer therapy-related cardiovascular toxicity

BACKGROUND

Coronary microvascular dysfunction (CMD) has been implicated as a potential mechanism in the pathophysiology of different clinical presentations, including ischemia and no obstructive coronary artery disease (INOCA), myocardial infarction and nonobstructive coronary arteries (MINOCA), stress cardiomyopathy, heart failure, and myocarditis. There are limited data about the role of CMD in cancer therapy-related cardiovascular toxicities.

CASE PRESENTATIONS

Four women with a diagnosis of active cancer receiving treatment who developed subsequent MINOCA or INOCA presented for cardiac catheterization. Upon coronary angiography showing no obstructive coronary arteries, coronary function testing was performed to evaluate for CMD.

METHODS

Coronary physiology was assessed measuring non-hyperemic (resting full-cycle ratio [RFR]) and hyperemic (fractional flow reserve [FFR]) indices using a physiologic pressure wire. The wire also measured coronary flow reserve (CFR), index of microcirculatory resistance (IMR), and RFR using thermodilution technology. CMD was confirmed if the CFR was <2.5 and the IMR was >25.

RESULTS

Among 4 patients with diagnosis of active cancer presenting with chest pain, there was no evidence of obstructive coronary artery disease, leading to separate diagnoses of INOCA, MINOCA, stress cardiomyopathy, and myocarditis. We found CMD in 2 patients (1 with INOCA and 1 with immune checkpoint inhibitor-related myocarditis).

CONCLUSIONS

CMD may play a role in cardiovascular toxicities. Further coronary physiology studies are needed to understand the mechanisms of cancer therapy-related cardiovascular toxicity and CMD, as well as optimal preventive and treatment options.

Differentiating Macrovascular and Microvascular Ischemia Using Fractal Analysis of Dynamic Myocardial Perfusion Stress-CT

OBJECTIVES

Fractal analysis of dynamic myocardial stress computed tomography perfusion imaging (4D-CTP) has shown potential to noninvasively differentiate obstructive coronary artery disease (CAD) and coronary microvascular disease (CMD). This study validates fractal analysis of 4D-CTP in a multicenter setting and assesses its diagnostic accuracy in subgroups with ischemia and nonobstructed coronary arteries (INOCA) and with mild to moderate stenosis.

MATERIALS AND METHODS

From the AMPLIFiED multicenter trial, patients with suspected or known chronic myocardial ischemia and an indication for invasive coronary angiography were included. Patients underwent dual-source CT angiography, 4D-CTP, and CT delayed-enhancement imaging. Coronary artery disease, CMD, and normal perfusion were defined by a combined reference standard comprising invasive coronary angiography with fractional flow reserve, and absolute or relative CT-derived myocardial blood flow. Nonobstructed coronary arteries were defined as ≤25% stenosis and mild to moderate stenosis as 26%-80%.

RESULTS

In 127 patients (27% female), fractal analysis accurately differentiated CAD (n = 61, 23% female), CMD (n = 23, 30% female), and normal perfusion (n = 34, 35% female) with a multiclass area under the receiver operating characteristic curve (AUC) of 0.92 and high agreement (multiclass κ = 0.89). In patients with ischemia (n = 84), fractal analysis detected CAD (n = 61) over CMD (n = 23) with sensitivity of 95%, specificity of 74%, accuracy of 89%, and AUC of 0.83. In patients with nonobstructed coronary arteries (n = 33), INOCA (n = 15) was detected with sensitivity of 100%, specificity of 78%, accuracy of 88%, and AUC of 0.94. In patients with mild to moderate stenosis (n = 27), fractal analysis detected CAD (n = 19) over CMD with sensitivity of 84%, specificity of 100%, accuracy of 89%, and AUC of 0.95.

CONCLUSIONS

In this multicenter study, fractal analysis of 4D-CTP accurately differentiated CAD and CMD including subgroups with INOCA and with mild to moderate stenosis.

Multiple Phenotypes of Chronic Coronary Syndromes Identified by ABCDE Stress Echocardiography

BACKGROUND

Regional wall motion abnormality is considered a sensitive and specific marker of ischemia during stress echocardiography (SE). However, ischemia is a multifaceted entity associated with either coronary artery disease (CAD) or angina with normal coronary arteries, a distinction difficult to make using a single sign. The aim of this study was to evaluate the diagnostic potential of the five-step ABCDE SE protocol for CAD detection.

METHODS

From the 2016-2022 Stress Echo 2030 study data bank, 3,229 patients were selected (mean age, 66 ± 12 years; 2,089 men [65%]) with known CAD (n = 1,792) or angina with normal coronary arteries (n = 1,437). All patients were studied using both the ABCDE SE protocol and coronary angiography, within 3 months. In step A, regional wall motion abnormality is assessed; in step B, B-lines and diastolic function; in step C, left ventricular contractile reserve; in step D, coronary flow velocity reserve in the left anterior descending coronary artery; and in step E, heart rate reserve.

RESULTS

SE response ranged from a score of 0 (all steps normal) to a score of 5 (all steps abnormal). For CAD, rates of abnormal results were 347 for step A (19.4%), 547 (30.5%) for step B, 720 (40.2%) for step C, 615 (34.3%) for step D, and 633 (35.3%) for step E. For angina with normal coronary arteries, rates of abnormal results were 81 (5.6%) for step A, 429 (29.9%) for step B, 432 (30.1%) for step C, 354 (24.6%) for step D, and 445 (31.0%) for step E. The dominant "solitary phenotype" was step B in 109 patients (9.1%).

CONCLUSIONS

Stress-induced ischemia presents with a wide range of diagnostic phenotypes, highlighting its complex nature. Using a comprehensive approach such as the advanced ABCDE score, which combines multiple markers, proves to be more valuable than relying on a single marker in isolation.

Comparison of risk profiles of participants in the Women's IschemiA TRial to Reduce events In non-ObstRuctive CAD (WARRIOR) trial, using Coronary Computed Tomography Angiography vs Invasive Coronary Angiography

OBJECTIVE

To compare baseline characteristics of participants in the Women's IschemiA TRial to Reduce Events In Non-ObstRuctive CAD (WARRIOR) trial by qualification by Coronary Computed Tomography Angiography (CCTA) or Invasive Coronary Angiography (ICA).

METHODS

The WARRIOR trial (NCT03417388) is an ongoing multicenter, prospective, randomized, blinded outcome evaluation of intensive medical therapy vs. usual care in women with suspected Ischemia and No Obstructive Coronary Artery Disease (INOCA) identified by either CCTA or ICA on the outcome of major adverse cardiovascular events (MACE). No obstructive coronary artery disease is defined as <50% luminal stenosis and normal coronary arteries is defined as no evidence of atherosclerosis including calcified and non-calcified plaque. Data presented was extracted on May 27, 2020. No clinical outcomes were assessed.

RESULTS

An initial sample cohort of 797 women was included. The majority were younger than 65 years, White participants (73.3%), 159 had diabetes (19.9%), and 676 had angina (84.8%) with the remainder having symptoms of suspected ischemic heart disease. Over 50% of randomized participants had normal coronaries without luminal irregularities by ICA or CCTA. Participants randomized to ICA were more likely to have worse baseline clinical risk profiles with older age, higher burden of cardiac risk factors and poor quality of life with disabling angina.

CONCLUSIONS

Among this initial sample of women with suspected INOCA randomized in the WARRIOR trial, there is a differential baseline cardiac risk of participants enrolled after CCTA or ICA. However, the majority had no evidence of atherosclerotic plaque or obstructive stenosis, after evaluation by ICA or CCTA. These results suggest that non-invasive evaluation with CCTA is likely to be associated with lower risk of MACE.

Prognostic value of myocardial flow reserve measured with CZT cardiac-dedicated SPECT low-dose dynamic myocardial perfusion imaging in patients with INOCA

BACKGROUND

Clinical use of dynamic myocardial perfusion imaging (D-MPI) of cadmium-zinc-telluride (CZT) cardiac-dedicated SPECT is growing, showing a higher application value than conventional SPECT. The prognostic value of ischemia in patients with non-obstructive coronary arteries (INOCA) remains an important challenge for investigation. The primary objective of this study was to investigate the prognostic value of myocardial flow reserve (MFR) measured with low-dose D-MPI of CZT cardiac-dedicated SPECT in the assessment of patients with INOCA.

METHODS

Consecutive screening of patients with INOCA and obstructive coronary artery disease (OCAD) who had coronary angiography (CAG) data was performed within three months before or after D-MPI imaging. The patients who met the inclusion criteria were retrospectively analyzed and follow-up by telephone was performed. The enrolled patients were then divided into the INOCA and OCAD groups. INOCA was defined as signs and/or symptoms of myocardial ischemia but with < 50% epicardial stenosis. OCAD was defined as obstructive stenosis (≥ 50% stenosis) of epicardial coronary arteries or their major branches on the CAG. Medical treatments, Seattle Angina Questionnaire (SAQ) scores, and major adverse cardiac events (MACEs) were studied. The Kaplan-Meier survival curve, Log-rank test, and univariable COX regression analysis were used to evaluate the prognosis of patients and associated predictors, with P < 0.05 being considered statistically significant.

RESULTS

A total of 303 patients (159 males and 144 females) were enrolled for the final analysis after excluding 24 patients who were lost to follow-up. The mean age of the included cases was 61.94 ± 8.59 years, of which 203 (67.0%) cases were OCAD and 100 (33.0%) cases were INOCA, respectively. The median follow-up was 16 months (14-21 months). Kaplan-Meier survival curves showed that the incidence of MACE was similar in the INOCA and OCAD groups (log-rank P = 0.2645), while those with reduced MFR showed a higher incidence of MACE than those with normal MFR (log-rank P = 0.0019). The subgroup analysis in the OCAD group revealed that 105 patients with reduced MFR had a higher incidence of MACE than those with normal MFR (log-rank P = 0.0226). The subgroup analysis in the INOCA group showed that 37 patients with reduced MFR had a higher incidence of MACE than those with normal MFR in the INOCA group (log-rank P = 0.0186). Univariable Cox regression analysis showed for every 1 unit increase in MFR, the risk of MACE for INOCA was reduced by 66.1% and that for OCAD by 64.2%. For each 1 mL·g-1·min-1 increase in LV-sMBF, the risk of MACE was reduced by 72.4% in INOCA patients and 63.6% in OCAD patients.

CONCLUSIONS

MFR measured with low-dose D-MPI CZT SPECT provides incremental prognostic value in patients with INOCA. Patients with reduced MFR show an increased risk of MACE, increased symptom burdens, and impaired quality of life. INOCA patients with reduced MFR experienced higher rate of MACE than OCAD patients with normal MFR.

Sex differences in diagnostic modalities of atherosclerosis in the macrocirculation

Asymptomatic atherosclerosis begins early in life and may progress in a sex-specific manner to become the major cause of cardiovascular morbidity and death. As diagnostic tools to evaluate atherosclerosis in the macrocirculation, we discuss imaging methods (in terms of computed tomography, positron emission tomography, intravascular ultrasound, magnetic resonance imaging, and optical coherence tomography), along with derived scores (Agatston, Gensini, Leaman, Syntax), and also hemodynamic indices of vascular stiffness (including flow-mediated dilation, shear stress, pulse pressure, augmentation index, arterial distensibility), assessment of plaque properties (composition, erosion, rupture), stenosis measures such as fractional flow reserve. Moreover, biomarkers including matrix metalloproteinases, vascular endothelial growth factors and miRNAs, as well as the impact of machine learning support, are described. Special attention is given to age-related aspects and sex-specific characteristics, along with clinical implications. Knowledge gaps are identified and directions for future research formulated.

The role and mechanisms of microvascular damage in the ischemic myocardium

Following myocardial ischemic injury, the most effective clinical intervention is timely restoration of blood perfusion to ischemic but viable myocardium to reduce irreversible myocardial necrosis, limit infarct size, and prevent cardiac insufficiency. However, reperfusion itself may exacerbate cell death and myocardial injury, a process commonly referred to as ischemia/reperfusion (I/R) injury, which primarily involves cardiomyocytes and cardiac microvascular endothelial cells (CMECs) and is characterized by myocardial stunning, microvascular damage (MVD), reperfusion arrhythmia, and lethal reperfusion injury. MVD caused by I/R has been a neglected problem compared to myocardial injury. Clinically, the incidence of microvascular angina and/or no-reflow due to ineffective coronary perfusion accounts for 5-50% in patients after acute revascularization. MVD limiting drug diffusion into injured myocardium, is strongly associated with the development of heart failure. CMECs account for > 60% of the cardiac cellular components, and their role in myocardial I/R injury cannot be ignored. There are many studies on microvascular obstruction, but few studies on microvascular leakage, which may be mainly due to the lack of corresponding detection methods. In this review, we summarize the clinical manifestations, related mechanisms of MVD during myocardial I/R, laboratory and clinical examination means, as well as the research progress on potential therapies for MVD in recent years. Better understanding the characteristics and risk factors of MVD in patients after hemodynamic reconstruction is of great significance for managing MVD, preventing heart failure and improving patient prognosis.

Comprehensive Management of ANOCA, Part 1-Definition, Patient Population, and Diagnosis: JACC State-of-the-Art Review

Angina with nonobstructive coronary arteries (ANOCA) is increasingly recognized and may affect nearly one-half of patients undergoing invasive coronary angiography for suspected ischemic heart disease. This working diagnosis encompasses coronary microvascular dysfunction, microvascular and epicardial spasm, myocardial bridging, and other occult coronary abnormalities. Patients with ANOCA often face a high burden of symptoms and may experience repeated presentations to multiple medical providers before receiving a diagnosis. Given the challenges of establishing a diagnosis, patients with ANOCA frequently experience invalidation and recidivism, possibly leading to anxiety and depression. Advances in scientific knowledge and diagnostic testing now allow for routine evaluation of ANOCA noninvasively and in the cardiac catheterization laboratory with coronary function testing (CFT). CFT includes diagnostic coronary angiography, assessment of coronary flow reserve and microcirculatory resistance, provocative testing for endothelial dysfunction and coronary vasospasm, and intravascular imaging for identification of myocardial bridging, with hemodynamic assessment as needed.

Symptom Presentation among Women with Suspected Ischemia and No Obstructive Coronary Artery Disease (INOCA)

Identifying ischemic heart disease (IHD) in women based on symptoms is challenging. Women are more likely to endorse non-cardiac symptoms. More than 50% of women with suspected ischemia have no obstructive coronary disease (and thus, INOCA) and impaired outcomes during follow-up. We aimed to identify symptoms having predictive capacity for INOCA in women with clinical evidence of coronary ischemia. We included 916 women from the original WISE cohort (NCT00000554) who had coronary angiography performed for suspected ischemia and completed a 65-item WISE symptom questionnaire. Sixty-two percent (n = 567) had suspected INOCA. Logistic regression models using a best subsets approach were examined to identify the best predictive model for INOCA based on Score χ2 and AICc. A 10-variable, best-fit model accurately predicted INOCA (AUC 0.72, 95% CI 0.68, 0.75). The model indicated that age ≤ 55 years, left side chest pain, chest discomfort, neck pain, and palpitations had independent, positive relationship (OR > 1) to INOCA (p < 0.001 to 0.008). An inverse relationship (OR < 1) was observed for impending doom, and pain in the jaw, left or bilateral arm, and right hand, interpreted as INOCA associated with the absence of these symptoms (p ≤ 0.001 to 0.023). Our best-fit model accurately predicted INOCA based on age and symptom presentation ~72% of the time. While the heterogeneity of symptom presentation limits the utility of this unvalidated 10-variable model, it has promise for consideration of symptom inclusion in future INOCA prediction risk modeling for women with evidence of symptomatic ischemia.

The role of left ventricular hypertrophy measured by echocardiography in screening patients with ischaemia with non-obstructive coronary arteries: a cross-sectional study

Many patients with ischaemia with non-obstructive coronary arteries (INOCA) have a poor prognosis. This study aims to explore the diagnostic value of left ventricular hypertrophy (LVH)-related ultrasound parameters in INOCA patients. The study group consisted of 258 patients with INOCA in this retrospective cross-sectional study, and these patients were free of obstructive coronary artery disease, previous revascularization, atrial fibrillation, ejection fraction < 50%, major distortions of left ventricular geometry, suspected non-ischaemic causes. Control individuals were matched 1:1 with study group according to age, sex, cardiovascular risk factors, and time of hospital stay. According to left ventricular mass index (LVMI) and relative wall thickness, left ventricular geometry was composed of concentric hypertrophy, eccentric hypertrophy, concentric remodeling and normal geometry. LVH-related parameters, left ventricular geometry, demographic characteristics, laboratory parameters and other echocardiographic indicators were compared between the two groups. Subgroup analysis was performed based on sex. LVMI in the study group was higher than that in the control group (86.86 ± 18.83 g/m2 vs 82.25 ± 14.29 g/m2, P = 0.008). The ratio of LVH was higher in the study group (20.16% vs 10.85%, P = 0.006). After subgroup analysis based on sex, LVMI differences (85.77 ± 18.30 g/m2 vs 81.59 ± 14.64 g/m2, P = 0.014) and the ratio of LVH differences (25.00% vs 14.77%, P = 0.027) still existed in females between the two groups. There was no difference in the constituent ratio of left ventricular geometry between the two groups (P = 0.157). Sex-based subgroup analysis showed no difference in the constituent ratio of left ventricular geometry between the two groups in females (P = 0.242). The degree of LVH in the study group was higher than that in the control group, suggesting that LVH may play an important role in the occurrence and development of INOCA. Moreover, LVH-related ultrasound parameters may be of higher diagnostic value for female INOCA patients than for male INOCA patients.

Coronary revascularization for heart failure with coronary artery disease: A systematic review and meta-analysis of randomized trials

AIMS

Coronary artery disease (CAD) is a common cause of heart failure (HF). Whether coronary revascularization improves outcomes in patients with HF receiving guideline-recommended pharmacological therapy (GRPT) remains uncertain; therefore, we conducted a systematic review and meta-analysis of relevant randomized controlled trials (RCTs).

METHODS AND RESULTS

We searched in public databases for RCTs published between 1 January 2001 and 22 November 2022, investigating the effects of coronary revascularization on morbidity and mortality in patients with chronic HF due to CAD. All-cause mortality was the primary outcome. We included five RCTs that enrolled, altogether, 2842 patients (most aged <65 years; 85% men; 67% with left ventricular ejection fraction ≤35%). Overall, compared to medical therapy alone, coronary revascularization was associated with a lower risk of all-cause mortality (hazard ratio [HR] 0.88, 95% confidence interval [CI] 0.79-0.99; p = 0.0278) and cardiovascular mortality (HR 0.80, 95% CI 0.70-0.93; p = 0.0024) but not the composite of hospitalization for HF or all-cause mortality (HR 0.87, 95% CI 0.74-1.01; p = 0.0728). There were insufficient data to show whether the effects of coronary artery bypass graft surgery or percutaneous coronary intervention were similar or differed.

CONCLUSIONS

For patients with chronic HF and CAD enrolled in RCTs, the effect of coronary revascularization on all-cause mortality was statistically significant but neither substantial (HR 0.88) nor robust (upper 95% CI close to 1.0). RCTs were not blinded, which may bias reporting of the cause-specific reasons for hospitalization and mortality. Further trials are required to determine which patients with HF and CAD obtain a substantial benefit from coronary revascularization by either coronary artery bypass graft surgery or percutaneous coronary intervention.

The role of coronary computed tomography angiography in low- and intermediate-risk patients with chest pain: a paradigm shift in modern cardiology

Chest pain is a common complaint among patients presenting to primary care physicians. The management of chest pain secondary to coronary artery disease is rapidly changing as new evidence increase our knowledge of this complex clinical problem. The 2021 multisociety guidelines developed by the American College of Cardiology and the American Heart Association along with other organizations and imaging societies represent the first international guidelines for the evaluation and diagnosis of patients with acute or stable chest pain. This review will discuss in details the evaluation of low- and intermediate risk subjects presenting with acute and stable chest pain both in the emergency and office settings, providing a practical approach, supported by contemporary evidence, for the management of this important clinical problem leveraging on the central role played by coronary computed tomography angiography as documented by current clinical guidelines and available scientific literature.

Ischemia With Nonobstructive Coronary Artery Disease: Concept, Assessment, and Management

In daily clinical practice, physicians often encounter patients with angina or those with evidence of myocardial ischemia from noninvasive tests but not having obstructive coronary artery disease. This type of ischemic heart disease is referred to as ischemia with nonobstructive coronary arteries (INOCA). INOCA patients often suffer from recurrent chest pain without adequate management and are associated with poor clinical outcomes. There are several endotypes of INOCA, and each endotype should be treated based on its specific underlying mechanism. Therefore, identifying INOCA and discriminating its underlying mechanisms are important issues and of clinical interest. Invasive physiologic assessment is the first step in the diagnosis of INOCA and discriminating the underlying mechanism; additional provocation tests help physicians identify the vasospastic component in INOCA patients. Comprehensive information acquired from these invasive tests can provide a template for mechanism-specific management for patients with INOCA.

Coronary Microvascular Spasm: Clinical Presentation and Diagnosis

Professor Maseri pioneered the research and treatment of coronary vasomotion abnormalities represented by coronary vasospasm and coronary microvascular dysfunction (CMD). These mechanisms can cause myocardial ischaemia even in the absence of obstructive coronary artery disease, and have been appreciated as an important aetiology and therapeutic target with major clinical implications in patients with ischaemia with non-obstructive coronary artery disease (INOCA). Coronary microvascular spasm is one of the key mechanisms responsible for myocardial ischaemia in patients with INOCA. Comprehensive assessment of coronary vasomotor reactivity by invasive functional coronary angiography or interventional diagnostic procedure is recommended to identify the underlying mechanisms of myocardial ischaemia and to tailor the best treatment and management based on the endotype of INOCA. This review highlights the pioneering works of Professor Maseri and contemporary research on coronary vasospasm and CMD with reference to endothelial dysfunction, Rho-kinase activation and inflammation.