Ischemic Heart Disease

Ischemic heart disease, also called coronary artery disease or coronary heart disease, is the leading cause of death worldwide, affecting hundreds of millions of people and causing approximately 9 million deaths annually. The condition develops when the arteries supplying blood to the heart muscle (coronary arteries) become narrowed or blocked by a gradual buildup of fatty deposits called plaque. These plaques contain cholesterol, calcium, inflammatory cells, and other substances that accumulate in artery walls over years or decades—a process called atherosclerosis. As plaque grows, it narrows the artery opening, restricting blood flow to the heart muscle. This reduced blood flow causes chest pain or pressure (angina), particularly during physical activity or stress when the heart needs more oxygen. Sometimes a plaque can rupture, triggering blood clot formation that suddenly blocks the artery completely, causing a heart attack (myocardial infarction) that damages or kills heart muscle cells. Risk factors include high cholesterol (particularly LDL or "bad" cholesterol), high blood pressure, smoking, diabetes, obesity, sedentary lifestyle, family history, and age. Inflammation plays a central role throughout the disease process, both in plaque formation and in causing plaque rupture. While traditionally viewed as a plumbing problem requiring mechanical fixes, ischemic heart disease is now understood as an inflammatory disease influenced by genetics, lifestyle, and metabolic factors.

Treatment combines lifestyle changes, medications, and procedures to restore blood flow when needed. Lifestyle modifications—including heart-healthy diet, regular exercise, smoking cessation, weight management, and stress reduction—form the foundation of treatment and can significantly slow disease progression. Medications include statins to lower cholesterol and stabilize plaque, antiplatelet drugs (aspirin, clopidogrel) to prevent blood clots, beta-blockers to reduce heart workload, ACE inhibitors or ARBs to lower blood pressure and protect the heart, and nitrates for angina relief. PCSK9 inhibitors, newer injectable medications that dramatically lower LDL cholesterol, are available for people who can't reach goals with statins alone or can't tolerate statins. For significantly blocked arteries causing symptoms despite medication, percutaneous coronary intervention (PCI)—commonly called angioplasty with stent placement—involves threading a catheter through blood vessels to the blockage, inflating a balloon to widen the artery, and placing a mesh tube (stent) to keep it open. Coronary artery bypass grafting (CABG) surgery creates new routes for blood flow around blockages using blood vessels taken from elsewhere in the body. Cardiac rehabilitation programs combining supervised exercise, education, and support improve outcomes after heart attacks or procedures. With current treatments, many people with ischemic heart disease manage their condition effectively and maintain good quality of life for decades.

Despite optimal treatment with lifestyle changes and multiple medications, many people continue experiencing cardiovascular events—this "residual risk" represents an important treatment gap. Some individuals can't tolerate statins due to muscle pain or other side effects, leaving their cholesterol inadequately controlled. Diffuse disease affecting long segments of arteries or very small vessels (microvascular disease) isn't amenable to stenting or bypass surgery, limiting options for these patients. Chronic total occlusions—arteries completely blocked for extended periods—remain technically challenging to open even with advanced techniques. Recurrent blockages within stents (restenosis) occur in some patients despite drug-eluting stent technology. Antiplatelet medications necessary to prevent clots carry bleeding risks that can be serious, particularly in older patients or those needing other blood thinners, creating difficult treatment balance decisions. After heart attacks, some people develop heart failure from damaged muscle, and current treatments can't fully restore lost function. Better methods to identify high-risk individuals before their first heart attack would enable earlier, more aggressive prevention. Inflammation persists even when cholesterol is well-controlled, contributing to ongoing risk that conventional treatments don't fully address.

Inclisiran, an siRNA drug that lowers cholesterol by silencing the gene producing PCSK9, is already approved in some countries and expanding globally—given by injection just twice yearly, it offers more convenient cholesterol management than current options requiring more frequent dosing. Novel anti-inflammatory therapies are in Phase 3 trials following the approval of low-dose colchicine for cardiovascular protection, with drugs targeting specific inflammatory pathways including interleukin inhibitors being evaluated. Gene therapies delivering instructions to lower cholesterol or produce protective proteins are advancing through trials, potentially offering one-time treatments with lasting effects. New antiplatelet drugs with improved safety profiles and different mechanisms of action than current medications are being tested to reduce bleeding risk while maintaining clot prevention. Therapies promoting growth of collateral blood vessels (natural bypasses around blockages) are in trials, potentially helping patients with diffuse disease who aren't surgical candidates. Cell-based therapies delivering stem cells or cardiac progenitor cells to repair heart tissue after heart attacks are in advanced trials, aiming to regenerate damaged muscle rather than just limiting further damage. Next-generation stents with improved coatings and designs to reduce restenosis and thrombosis risk are being evaluated. Drugs targeting lipoprotein(a)—an inherited cholesterol particle that increases cardiovascular risk independently of LDL—are in late-stage trials after decades without treatments specifically addressing this risk factor.

CRISPR gene editing is being explored to permanently disable the PCSK9 gene in the liver through one-time treatment, potentially providing lifelong cholesterol reduction, with early human trials already underway. mRNA vaccine technology—proven in COVID-19 vaccines—is being adapted to treat cardiovascular disease, including approaches to lower cholesterol, reduce inflammation, or promote blood vessel growth. Scientists are developing nanotechnology-based drug delivery systems that could target medications specifically to atherosclerotic plaques, concentrating treatment where needed while reducing systemic exposure. Researchers are investigating the gut microbiome's role in heart disease, with evidence that certain bacteria produce compounds affecting cholesterol metabolism, inflammation, and blood pressure—interventions to modify intestinal bacteria are being explored. Artificial intelligence is being applied to identify individuals at highest risk before symptoms appear by analyzing genetic data, imaging, electronic health records, and wearable device data, enabling earlier intervention. Scientists are developing drugs to stabilize vulnerable plaques prone to rupture rather than just shrinking them. Mitochondrial-targeted therapies aim to protect heart cells' energy-producing structures from damage during heart attacks, potentially limiting muscle death. Researchers are exploring senolytic drugs that eliminate senescent cells contributing to vascular aging and atherosclerosis. Novel imaging agents and techniques are being developed to detect high-risk plaques before they cause events. Scientists are investigating ways to reprogram scar tissue back into functioning heart muscle after heart attacks through cellular reprogramming techniques. Researchers are studying hibernating animals that naturally protect their hearts during extreme conditions, seeking insights applicable to human cardiovascular protection.