Heart attack, cardiac arrest, heart failure, and complete heart block. What are the differences?

Many individuals suffer from various forms of heart ailments. In most countries, including Jamaica, heart and vascular diseases are the most common causes of death and major disabilities. Heart and vascular diseases also result in enormous economic cost to society from reduced productivity as patients tend to be individuals in their most productive years of life.

There is overwhelming evidence that investment in infrastructure and human capital to address cardiovascular disease results in earlier diagnosis, better treatment, and improved outcomes. Better diagnosis and treatment of heart and vascular diseases lead to a more productive workforce and, ultimately, national economic growth. Unfortunately, many low-resource nations have limited capacity to address cardiovascular disease and citizens suffer from misdiagnosis and improper treatment.

A starting point in the discussion would seem to be an enlightenment campaign to educate the public and stakeholders on the various forms of heart disease and the unique differences in terms of presentation, diagnosis, and treatment and the resources needed to effectively respond to them. Only when this is fully appreciated can the national will be summoned to remove the structural barriers that limit the development of cardiovascular care options that meet international standards of care and best practices.

There seems to be a general lack of knowledge of the differences between various forms of heart diseases and how they are diagnosed or treated or what human and infrastructural resources are required to effectively respond to them and, more importantly, their significance, both to the individual and the society.

Heart and vascular diseases include a wide array of ailments such as heart attack, heart failure, heart blocks, sudden cardiac arrest, heart defects from birth, aortic aneurysm (an abnormal enlargement or bulging of a section of the wall of the aorta, which is the main blood vessel carrying blood from the heart to the rest of the body), vascular diseases of the limbs, high blood pressure, high cholesterol, arrhythmia (a problem with the rhythm or rate of the heartbeat), and an enlarged heart muscle (cardiomyopathy).

There are two major forms of heart disease that are often misunderstood, and sometimes assumed to be the same by the public, even though they are distinctively different from each other.

Heart Attack (Myocardial Infarction or MI)

A heart attack occurs when circulation is blocked or cut off, leading to an abrupt cessation of blood supply to the heart muscle. The sudden blockage of circulation deprives the heart of the oxygen and vital nutrients that it needs for proper function. Heart attacks are among the most catastrophic forms of heart disease and require immediate intervention to reduce the risk of death or major complications.

In our previous columns, we have discussed the concept of door to balloon time (D2B), which is an internationally accepted practice standard requiring rapid intervention with balloon angioplasty procedure to open the blockage, preferably within 90 minutes of a heart attack patient arriving at hospital. At the Heart Institute of the Caribbean (HIC Heart Hospital), we have maintained a mean door to balloon time of 65 minutes.

Heart attacks occur due to rupture of cholesterol plaques in the heart vessel. Plaque is formed when cholesterol combines with fat, calcium, and other substances in the blood. Cholesterol/fat plaques build up on the arteries of individuals at risk over time and when they rupture, a cascade of events follow, causing blood clots to form.

Large clots can block the flow of blood through a coronary artery, resulting in a heart attack. Other more uncommon causes of heart attacks include intense spasm of the heart vessel or spontaneous tear (dissection) of the heart vessel shutting off flow of blood to the heart muscles depriving the muscles of oxygen and essential nutrients.

Cardiac arrest/Sudden cardiac arrest

Contrary to what many people think or believe, a cardiac arrest is not the same thing as a heart attack. As we described earlier, a heart attack is caused by a blockage or tear causing an abrupt interruption in blood flow to the heart muscle.

A cardiac arrest is triggered by an electrical disturbance that adversely affects the ability of the heart to beat in a manner that can generate adequate cardiac output to power the heart. While a heart attack is different from a cardiac arrest, a heart attack may lead to a cardiac arrest. Cardiac arrest can be a catastrophic complication of a heart attack but can also occur independent of a heart attack.

Cardiac arrest can be a significant problem in individuals with a particular genetic marker that results in abnormal thickening of the heart muscle, leading to a distortion in normal electrical conduction activities in the heart muscle. Such individuals may be at risk of cardiac arrest or sudden death when they engage in vigorous sporting activities, as recently reported with professional football player Christian Erickson.

When a cardiac arrest occurs, the heart can get out of rhythm, resulting in rapid and irregular heartbeats, which makes the heart unable to function effectively. If the electrical disturbance is significant or prolonged in duration it may cause the heart to stop functioning and result in sudden cardiac death. Without immediate resuscitation, survival will be unlikely.

Unlike a heart attack, where there may be warning signs and symptoms (except in silent heart attacks), most cases of cardiac arrest happen without warning signs. While some people may have experienced light-headedness, fainting, and brief loss of consciousness that may represent aborted sudden death episodes, most individuals presenting with cardiac arrest or sudden death report no prior symptoms before a collapse with loss of consciousness, pulse, and spontaneous breathing.

As with a heart attack, survival is possible but only with rapid and appropriate intervention by trained people and ultimately a focused therapeutic intervention at a facility with proper infrastructure and experienced heart care team.

Cardiopulmonary resuscitation (CPR), either via chest compressions or a defibrillator, is the hallmark of early intervention to save a life when a cardiac arrest occurs, until definitive therapy can be administered at a well-equipped treatment facility. Once the pulse is restored, it is critical to get such an individual to an appropriate heart care centre with appropriate infrastructure and experience. Failing to do that, death will ultimately ensue.

Because heart attacks and cardiac arrests can occur at any time, a heart care centre must be fully equipped and staffed to respond to these emergencies 24/7. The HIC Heart Hospital is set up to do just that.

In a future column, we will discuss heart failure and complete heart block, two other serious cardiac conditions that are often misunderstood and frequently mismanaged despite significant advances in treatment options.

— Dr Ernest Madu, MD, FACC and Dr Paul Edwards, MD, FACC are consultant cardiologists at Heart Institute of the Caribbean (HIC) and HIC Heart Hospital. Correspondence to info@caribbeanheart.com or call 876-906-2107