The Myth of the Mild Vulnerable Plaques

Mental stress, atheroma, myocardial ischaemia and injury: the link is inflammation

Increasing observational and experimental trial data have shown that mental stress can lead to an increase in adverse clinical cardiovascular events. Mental stress affects the heart by inducing ischaemia and precipitating myocardial infarction (MI) or direct myocardial injury. Mental stress leads to systemic inflammation. Inflammation is known to cause rapid atheromatous plaque progression, instability and thrombosis-the classic type 1 MI. Inflammation can also lead to type 2 MI or myocarditis and injury. The published data linking systemic inflammation, mental stress and cardiovascular disease will be reviewed to establish the linkage between mind and heart, thereby highlighting the importance of holistically managing the patient, not only addressing separate organ systems. Finally, recent trial evidence showing the value of anti-inflammatory drugs in cardiovascular and mental conditions will be briefly considered.

Quantitative flow ratio derived pullback pressure gradient and CZT-SPECT measured longitudinal flow gradient for hemodynamically significant coronary artery disease

BACKGROUND

Whether physiological coronary diffuseness assessed by quantitative flow reserve (QFR) pullback pressure gradient (PPG) correlates with longitudinal myocardial blood flow (MBF) gradient and improves diagnostic performances for myocardial ischemia remains unknown.

METHODS AND RESULTS

MBF was measured in mL g-1 min-1 with 99mTc-MIBI CZT-SPECT at rest and stress, corresponding myocardial flow reserve (MFR = MBF stress/MBF rest) and relative flow reserve (RFR = MBF stenotic area/MBF reference) were calculated. Longitudinal MBF gradient was defined as apical and basal left ventricle MBF gradient. △longitudinal MBF gradient was calculated by longitudinal MBF gradient at stress and rest. QFR-PPG was acquired from virtual QFR pullback curve. QFR-PPG significantly correlated with hyperemic longitudinal MBF gradient (r = 0.45, P = 0.007) and △longitudinal MBF gradient (stress-rest) (r = 0.41, P = 0.016). Vessels with lower RFR had lower QFR-PPG (0.72 vs. 0.82, P = 0.002), hyperemic longitudinal MBF gradient (1.14 vs. 2.22, P = 0.003) and △longitudinal MBF gradient (0.50 vs. 1.02, P = 0.003). QFR-PPG, hyperemic longitudinal MBF gradient and △longitudinal MBF gradient showed comparable diagnostic performances for predicting decreased RFR (area under curve [AUC]: 0.82 vs. 0.81 vs. 0.75, P = NS) or QFR (AUC: 0.83 vs. 0.72 vs. 0.80, P = NS). In addition, QFR-PPG and QFR in combination showed incremental value compared with QFR for predicting RFR (AUC = 0.83 vs. 0.73, P = 0.046, net reclassification index = 0.508, P = 0.001).

CONCLUSION

QFR-PPG significantly correlated with longitudinal MBF gradient and △longitudinal MBF gradient when used for physiological coronary diffuseness assessment. All three parameters had high accuracy in predicting RFR or QFR. Adding physiological diffuseness assessment increased accuracy for predicting myocardial ischemia.

Integrated coronary disease burden and patterns to discriminate vessels benefiting from percutaneous coronary intervention

OBJECTIVE

To evaluate the prognostic implications of atherosclerosis functional pattern on ischemia-causing vessels received percutaneous coronary intervention (PCI) or conservative treatment.

BACKGROUND

Quantitative flow ratio (QFR)-derived pullback pressure gradient (PPG) index is recently proposed to characterize atherosclerosis functional pattern, but its prognostic value remains unclear.

METHODS

QFR-derived PPG index was retrospectively calculated in patients from the PANDA III trial. Vessels with low or high PPG treated by PCI or not were compared for the risk of 2-year vessel-oriented composite outcome (VOCO), which was a composite of vessel-related ischemia-driven revascularization, vessel-related myocardial infarction, or cardiac death.

RESULTS

A total of 1444 vessels were included while 94 (6.5%) VOCOs occurred within 2 years. Among physiologically ischemic vessels (QFR ≤ 0.80) treated by PCI, those with low PPG acquired higher VOCO risk than those with high PPG (8.4% vs. 3.8%; adjusted hazard ratio [HR] 2.13, 95% confidence interval [CI] 1.18 to 3.86), and a similar VOCO risk (8.4% vs. 7.8%; adjusted HR 1.11, 95%CI 0.70-1.78) compared to those treated by conservatively. After multiple adjustment, PPG index was an independent predictor for VOCO (HR 1.30, 95% CI 1.05-1.62). The addition of PPG to the model of clinical risk factors substantially improved the predictions of VOCO (C-index 0.67 vs. 0.62, net reclassification index 0.42).

CONCLUSIONS

PCI treatment was associated with improved outcomes in vessels with high PPG, but not for those with low PPG, which acquired similar risk of VOCO compared to vessels treated conservatively. QFR-derived PPG might assist the treatment strategy selection in ischemia-causing vessels.

Coronary circulation: Pressure/flow parameters for assessment of ischemic heart disease

Both invasive and non-invasive parameters have been reported for assessment of the physiological status of the coronary circulation. Fractional flow reserve and coronary (or myocardial) flow reserve may be obtained by invasive or non-invasive means. These metrics of coronary stenosis severity have achieved wide clinical acceptance for guiding revascularization decisions and risk stratification. Other indices are obtained invasively (e.g., instantaneous wave-free ratio, iFR; hyperemic stenosis resistance) or non-invasively (e.g., PET absolute myocardial blood flow (mL/min/g)) and have been used for the same purposes. Both iFR, and whole-cycle distal coronary to aortic mean pressure (Pd/Pa) are measured under basal condition and used for assessment of hemodynamic stenosis severity as is index of basal stenosis resistance (BSR). These metrics typically are dichotomized at an empirically derived cut point into "normal" and "abnormal" categories for purposes of clinical decision making and data analysis. Once dichotomized the indices do not always point in the same direction and so confusion may arise. This review, therefore, will present basic principles relevant to understanding commonly employed metrics of the physiological status of the coronary circulation, potential strengths and weaknesses, and hopefully an improved appreciation of the clinical information provided by each.

ST elevation myocardial infarction

ST segment elevation myocardial infarction remains a significant contributor to morbidity and mortality worldwide, despite a declining incidence and better survival rates. It usually results from thrombotic occlusion of a coronary artery at the site of a ruptured or eroded plaque. Diagnosis is based on characteristic symptoms and electrocardiogram changes, and confirmed subsequently by raised cardiac enzymes. Prognosis is dependent on the size of the infarct, presence of collaterals and speed with which the occluded artery is reopened. Mechanical reperfusion by primary percutaneous coronary intervention is superior to fibrinolytic therapy if delivered by an experienced team in a timely fashion. Post-reperfusion care includes monitoring for complications, evaluation of left ventricular function, secondary preventive therapy and cardiac rehabilitation.

Emergence of Nonobstructive Coronary Artery Disease: A Woman's Problem and Need for Change in Definition on Angiography

Recognition of ischemic heart disease (IHD) is often delayed or deferred in women. Thus, many at risk for adverse outcomes are not provided specific diagnostic, preventive, and/or treatment strategies. This lack of recognition is related to sex-specific IHD pathophysiology that differs from traditional models using data from men with flow-limiting coronary artery disease (CAD) obstructions. Symptomatic women are less likely to have obstructive CAD than men with similar symptoms, and tend to have coronary microvascular dysfunction, plaque erosion, and thrombus formation. Emerging data document that more extensive, nonobstructive CAD involvement, hypertension, and diabetes are associated with major adverse events similar to those with obstructive CAD. A central emerging paradigm is the concept of nonobstructive CAD as a cause of IHD and related adverse outcomes among women. This position paper summarizes currently available knowledge and gaps in that knowledge, and recommends management options that could be useful until additional evidence emerges.

Coronary artery wall imaging

Like X-Ray contrast angiography, MR coronary angiograms show the vessel lumens rather than the vessels themselves. Consequently, outward remodeling of the vessel wall, which occurs in subclinical coronary disease before luminal narrowing, cannot be seen. The current gold standard for assessing the coronary vessel wall is intravascular ultrasound, and more recently, optical coherence tomography, both of which are invasive and use ionizing radiation. A noninvasive, low-risk technique for assessing the vessel wall would be beneficial to cardiologists interested in the early detection of preclinical disease and for the safe monitoring of the progression or regression of disease in longitudinal studies. In this review article, the current state of the art in MR coronary vessel wall imaging is discussed, together with validation studies and recent developments.

Clinical classification of plaque morphology in coronary disease

In published post-mortem pathological studies, more than two-thirds of acute coronary events are associated with the rupture of lipid-rich, voluminous, and outwardly remodelled plaques covered by attenuated and inflamed fibrous caps in the proximal part of coronary arteries. Superficial erosion of the plaques is responsible for most of the remaining events; the eroded plaques usually do not demonstrate much lipid burden, do not have thin fibrous caps, are not positively remodelled, and are not critically occlusive. Both noninvasive and invasive imaging studies have been performed to clinically define the plaque characteristics in acute coronary syndromes in an attempt to identify the high-risk plaque substrate susceptible to development of an acute coronary event. Optical coherence tomography (OCT)--an intravascular imaging modality with high resolution--can be used to define various stages of plaque morphology, which might allow its use for the identification of high-risk plaques vulnerable to rupture, and their amenability to pre-emptive interventional treatment. OCT might also be employed to characterize plaque pathology at the time of intervention, to provide a priori knowledge of the mechanism of the acute coronary syndrome and, therefore, to enable improved management of the condition.