Why heart attacks are more common in the morning

What time of the day are heart attacks most common, why? How do we know if someone is having a heart attack and what should we do if someone has an attack?​

If you divide the day into four six-hour periods, the most common time of day for heart attacks and for all kinds of cardiovascular emergency, including stroke, are the morning hours of 6 a.m. to noon. Nearly twice as many heart attacks occur during this period of the day than between midnight and 6 a.m., the time when the least number of attacks occur. Recent researches also indicate that morning heart attacks, which peak in incidence during the first three hours after waking up, are also more serious than heart attacks that happen on other times of the day.

 Mechanism of a heart attack 

A heart attack occurs when a coronary artery (a blood vessel that supplies our heart) that has previously narrowed because of coronary artery disease gets completely clogged, usually by a blood clot. This deprives part our heart of oxygenated blood, causes the death of muscle cells and leads to failure of our heart to pump enough blood to all parts of our body.

 We are more prone to heart attacks in the morning

We are more susceptible to a heart attack in the morning than at other times of the day because during this period there is a sudden increase demand on our heart, our coronary arteries are more constricted (i.e., narrower lumens) and our capacity to dissolve blood clots is diminished.

In the evening, when we are asleep, our cardiovascular system is in resting mode, which is characterized by low blood pressure and slow heart rate. Shortly before waking up, to awaken our cardiovascular system and prepare our body for the activities of the day—which entail a lot of oxygen consumption—certain hormones and chemical substances are released by some of our organs including cortisol and cathecolamines. These substances boost blood-pressure, heart rate, and blood-sugar levels while at the same time they narrow our blood vessels including the coronary arteries a little. In other words, they force our heart to suddenly work harder.

Likewise, in the early morning, our platelets, blood elements that initiate the formation of  blood clots that could clog coronary arteries, are particularly adhesive to the blood vessels. We have a system, fibrinolytic system, to dissolve blood clots, but in the morning, its activity is reduced.

For healthy people, these early morning events do not pose any problem. But for a person with a plaque in the coronary vessel because of coronary heart disease, they could precipitate a heart attack.

 How to tell when somebody is having a heart attack

Most people who develop a heart attack experience intermittent chest pains for days, months, or years before the attack, but in about a fifth of cases, the attack itself is the first and only presentation of a diseased heart. The most common manifestation of a heart attack is squeezing or pressing pain in the middle of the chest that lasts for more than a few minutes. The pain may spread to the left arm or jaw, back, right arm, or over the abdomen. But about a third of people who suffer an attack do not experience chest pain at all. Instead, pain is felt over the other areas stated above, or there may be no pain at all. Aside from pain, other symptoms of a heart attack include heavy sweating, anxiousness, shortness of breath, pounding of the heart, nausea and vomiting, and loss of consciousness.

 What to do when someone is having a heart attack

When you suspect somebody is having a heart attack, stop the person from further performing any physical activity, not even walking. If aspirin is available, make him/her chew then swallow one tablet. Then, carry the person gently and bring him/her immediately to a hospital.

Life-saving drugs that can quickly dissolve a blood clot in the heart are now available. But they have to be administered immediately (preferably within an hour after the onset of the heart attack) and in a hospital setting. In addition to, or as an alternative to clot-dissolving drugs, angioplasty can be performed. In angioplasty, a catheter with an inflatable segment is pushed through to the blocked artery, and inflated to break up the clot. Then, a mesh tube (stent) is inserted into the artery to keep it patent.

source: Manila Bulletin