Heart Attack Complications

Heart attacks most often affect the left ventricle, the pumping powerhouse of the heart. Damage to this chamber can significantly impair the heart’s ability to pump oxygen-rich blood to the body, which may result in heart failure. Heart failure causes blood to back up into the lungs, where excess fluid causes further complications. As the lungs accumulate fluid, breathing becomes difficult.

Heart failure is common in victims of an AMI. In fact, two-thirds of hospitalized heart attack patients are diagnosed with congestive heart failure following the AMI. A heart attack can lead to heart failure because the resulting damage to the cardiac muscle impairs the heart’s ability to pump.

Circulatory Shock and Heart Failure

Circulatory shock occurs with advanced heart failure or a severe heart attack. In either case, the heart muscle is so weak that it cannot maintain adequate blood pressure. Circulatory shock is a serious condition: internal organs that are deprived of oxygenated blood sustain serious damage. Kidney, liver and brain damage may all result from shock.

Like a heart attack or stroke, circulatory shock is a medical emergency that requires immediate treatment.

Arrhythmias: Irregular Heartbeat

An irregular heartbeat, or arrhythmia, is a common complication of both heart attacks and heart failure. An irregular heartbeat increases the stress on the heart and causes irregular blood flow in the heart. This irregular blood flow increases the risk of clot formation that can lead to a stroke. Changes to the electric impulses from the sinus node, the pacemaker of the heart, result in a number of different irregular heartbeats.

Sinus Tachycardia

A “normal” irregular heartbeat, sinus tachycardia refers to the natural increase in heartbeat when exercising or emotionally excited. Fevers can also cause sinus tachycardia. Sinus tachycardia poses no threat to a healthy heart. If heart failure or heart disease is a factor, sinus tachycardia may overwork the heart.

Atrial Fibrillation

A common irregular heartbeat, atrial fibrillation affects up to five percent of the American population. Atrial fibrillation causes a fast, irregular, heartbeat between five to seven times as fast as a normal heartbeat. The heart’s atrial chambers “quiver” at high speeds, and are unable to pump blood effectively. Over time, blood pools in the atrium and may clot.

Risk factors for atrial fibrillation include heart failure, chronic lung disease, and a history of heart attacks. Although not life-threatening itself, atrial fibrillation increases the risk of strokes and heart failure.

Other Irregular Heartbeats

  • bradycardia: a slow irregular heartbeat.
  • premature ventricular contraction: a common irregular heartbeat where the heart “skips” a beat. This type of irregular heartbeat may be caused by heart damage, although it often occurs with otherwise healthy hearts.
  • ventricular tachycardia: a rapid heartbeat in the ventricles (120 per minute or more) that may impair the heart’s ability to pump effectively. This condition requires medical treatment if the blood pressure drops.
  • ventricular fibrillation: ventricle chambers beat so fast and irregular that blood is not pumped out of the heart. Ventricular fibrillation requires emergency defibrillation and medications: brain and heart damage may occur within five minutes without treatment.

Increased Risk of Stroke after a Heart Attack

Because of complications, such as heart failure and arrythmia, there is an increased risk of an ischemic stroke after a heart attack. An ischemic stroke occurs when arteries to the brain are blocked by atherosclerosis or clots, depriving the brain of sufficient oxygen. Without oxygen, brain cells die quickly, leading to areas of paralysis, seizures, comas, and, in some cases, death. Strokes can be small, affecting only a small area of the brain, or large, affecting large areas. With prompt treatment the damage caused by a stroke can be minimized. Stroke is the third leading cause of death in America and approximately 750,000 Americans suffer stokes annually.

Heart attacks can cause damage to the heart that leads to irregular blood flow in the heart. Any conditions of abnormal blood flow increase the risk of developing a clot in the heart. This clot may travel to the arteries of the brain and cause a stroke.


Mayo Foundation for Medical Education and Research. (2003). Stroke. Retrieved January 28, 2004, from www.mayoclinic.com/invoke.cfm?id=DS00150.

National Heart, Lung, and Blood Institute. (nd). What is a heart attack? Retrieved January 26, 2004, from dci.nhlbi.nih.gov/Diseases/HeartAttack/HeartAttack_WhatIs.html.

National Library of Medicine. (updated 2002). Cardiogenic shock. Retrieved January 28, 2004, from www.nlm.nih.gov/medlineplus/ency/article/000185.htm.