Coronary microvascular disease (CMD) refers to the subset of disorders affecting the structure and function of the coronary microcirculation, is prevalent in patients across a broad spectrum of ...cardiovascular risk factors, and is associated with an increased risk of adverse events. Contemporary evidence supports that most patients with CMD also have macrovessel atherosclerosis, which has important implications for their prognosis and management. In this state-of-the-art review, the authors summarize the pathophysiology of CMD, provide an update of diagnostic testing strategies, and classify CMD into phenotypes according to severity and coexistence with atherosclerosis. They examine emerging data highlighting the significance of CMD in specific populations, including obesity and insulin resistance, myocardial injury and heart failure with preserved ejection fraction, and nonobstructive and obstructive coronary artery disease. Finally, they discuss the role of CMD as a potential target for novel interventions beyond conventional approaches, representing a new frontier in cardiovascular disease reduction.
Cardiac amyloidosis, once considered untreatable, is now gaining well-deserved attention due to advances in imaging and the recent approval of targeted breakthrough therapies. In this paper, we ...discuss the role of radionuclide imaging in the evaluation and management of patients with the most common form of amyloidosis—cardiac transthyretin amyloidosis (ATTR). We provide a comprehensive summary of the literature interspersed with our institutional experience as appropriate, to deliver our perspective.
Abstract
Left ventricular (LV) hypertrophy (LVH) is a growth in left myocardial mass mainly caused by increased cardiomyocyte size. LVH can be a physiological adaptation to physical exercise or a ...pathological condition either primary, i.e. genetic, or secondary to LV overload. Patients with both primary and secondary LVH have evidence of coronary microvascular dysfunction (CMD). The latter is mainly due to capillary rarefaction and adverse remodelling of intramural coronary arterioles due to medial wall thickening with an increased wall/lumen ratio. An important feature of this phenomenon is the diffuse nature of this remodelling, which generally affects the coronary microvessels in the whole of the left ventricle. Patients with LVH secondary to arterial hypertension can develop both heart failure with preserved ejection fraction (HFpEF) and heart failure with reduced ejection fraction (HFrEF). These patients can develop HFrEF via a ‘direct pathway’ with an interval myocardial infarction and also in its absence. On the other hand, patients can develop HFpEF that can then progress to HFrEF with or without interval myocardial infarction. A similar evolution towards LV dysfunction and both HFpEF and HFrEF can occur in patients with hypertrophic cardiomyopathy, the most common genetic cardiomyopathy with a phenotype characterized by massive LVH. In this review article, we will discuss both the experimental and clinical studies explaining the mechanisms responsible for CMD in LVH as well as the evidence linking CMD with HFpEF and HFrEF.
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.
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).
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.
Background Cardiac amyloidosis is a substantially underdiagnosed disease, and contemporary estimates of the epidemiology of amyloidosis are lacking. This study aims to determine the incidence and ...prevalence of cardiac amyloidosis among Medicare beneficiaries from 2000 to 2012. Methods and Results Medicare beneficiaries were counted in the prevalence cohort in each year they had (1) ≥1 principal or secondary International Classification of Diseases, Ninth Revision code for amyloidosis and (2) ≥1 principal or secondary International Classification of Diseases, Ninth Revision code for heart failure or cardiomyopathy within 2 years after the systemic amyloidosis code. A beneficiary was counted in the incidence cohort only during the first year in which they met criteria. Primary outcomes included the prevalence and incidence of hospitalizations for cardiac amyloidosis. There were 4746 incident cases of cardiac amyloidosis in 2012 and 15 737 prevalent cases in 2012. There was also a significant increase in the prevalence rate (8 to 17 per 100 000 person-years) and incidence rate (18 to 55 per 100 000 person-years) from 2000 to 2012, most notable after 2006. Incidence and prevalence increased substantially more among men, the elderly, and in blacks. Conclusions The incidence and prevalence rates of cardiac amyloidosis are higher than previously thought. The incidence and prevalence rates of cardiac amyloidosis among hospitalized patients have increased since 2000, particularly among specific patient subgroups and after 2006, suggesting improved amyloidosis awareness and higher diagnostic rates with noninvasive imaging. In light of these trends, cardiac amyloidosis should be considered during the initial work up of patients ≥65 years old hospitalized with heart failure.
Quantitative myocardial perfusion PET/CT imaging is one of the most accurate tests for diagnosis and risk stratification of patients with suspected or known CAD. The test provides a comprehensive ...evaluation of patients with ischemic heart disease including quantitative assessments of regional myocardial perfusion, LV volumes and ejection fraction, calcified atherosclerotic burden, and myocardial blood flow and flow reserve (MFR). A normal stress myocardial blood flow and MFR (>2.0) has a very high negative predictive value and reliably excludes high-risk obstructive CAD. A global normal MFR (>2.0) identifies patients at consistently lower clinical risk. Conversely, a severely reduced MFR (<1.5) identifies patients at high clinical risk for adverse events regardless of whether this is due to obstructive CAD, microvascular dysfunction, or a combination of the 2. On the other hand, the delineation of atherosclerotic burden with either a formal quantitative coronary calcium score or by a semiquantitative assessment of the CT transmission scan is very helpful to guide the need for intensive preventive therapies. Recent evidence suggests that patients with angiographically obstructive CAD and a severe reduction in flow reserve (<1.6) may have a prognostic advantage from revascularization. This finding awaits confirmation by randomized clinical trials.
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