sudden cardiac death

In the Medical News: Time for Updated Guidelines for Athletes with Long QT Syndrome?

February 13, 2013 By Larry Creswell, MD Leave a Comment

A new study by Drs. Johnson and Ackerman from the Mayo Clinic just published in the British Journal of Sports Medicine cast doubt on the current guidelines for athletes with congenital long QT syndrome (LQTS).

In a previous post, I wrote about the condition known as LQTS. You may already know that this condition comes in an inherited, or congenital, form as well as an acquired form (as an unwanted side effect of various medications). Today, we’ll focus on the congenital form.

Patients–particularly young athletes–with congenital LQTS have a well-documented increased risk of sports-related sudden cardiac death (SCD). The magnitude of that risk depends upon the particular genetic defect responsible for the condition.

The latest consensus guidelines regarding athletes and heart disease were published in the United States in 2005 as Proceedings from the 36th Bethesda Conference and in that same year by European Society of Cardiology (ESC). To summarize these guidelines in a nutshell….

Bethesda Guidelines

1. Athletes should be limited to low-intensity sports (eg, billiards, bowling, cricket, curling, golf, riflery) if they have LQTS: with any symptoms; if the QTc is >470 msec for males or >480 msec for females; or if they have an internal cardioverter-defibrillator (ICD).

2. Athletes who are proven gene carriers for LQTS but who have no symptoms are allowed to participate fully in their sports.

ESC Guideline

1. Athletes with LQTS, regardless of the presence or absence of symptoms, are disqualified from participating in any sports.

In the new study, the investigators reported on their experience with 353 patients age 6 to 40 with long LQTS who were evaluated initially between 2000 and 2010. The majority of these patients–223–were not involved in sports or chose not to pursue their sports after their disease ws diagnosed. The focus of the study was on the remaining 130 athlete-patients: 60 male and 70 female athletes; 20 had an ICD.

Among the 130 athlete-patients, 70 were asymptomatic (participating in sports contrary to the ESC guidelines but within the Bethesda guidelines). The remaining 60 were symptomatic (and were participating in sports contrary to both sets of guidelines).

In follow-up that averaged 5.5 +/- 3.4 years, the authors reported that there was only 1 adverse event among the 130 athlete-patients–in one of the symptomatic patients (age 9) with an ICD who had an appropriate shock for a potentially fatal arrhythmia. Among the asymptomatic patients, there were no adverse events.

Conclusions and Implications

1. It’s important to remember that the vast majority of athlete-patients in this study were children and the findings may or may not extend to adult athletes with LQTS. Further investigation is needed in the adult athlete population with LQTS.

2. The current Bethesda and ESC guidelines for LQTS may be too restrictive, given the findings among the athlete-patients who continued their sports contrary to the 2005 guidelines. In this study, these patients rarely had adverse events.

3. It is still important for careful discussions regarding risk stratification (which may depend upon the precise genetic defect) and consideration of all treatment options before making decisions about continued participation in sports.

Related posts:

1. Long QT syndrome

2. Index to all of the posts at AthletesHeart through 2012

Long QT Syndrome

February 12, 2013 By Larry Creswell, MD Leave a Comment

Congenital long QT syndrome (LQTS) is an inherited condition that affects heart muscle cells and predisposes individuals to potentially fatal ventricular arrhythmias. This condition manifests (usually) with a prolonged time interval between the Q and T waves of the EKG and the occurence of either syncope (blacking out due to an arrhythmia) or sudden cardiac death (SCD) that is usually triggered by emotional stress or exercise.

Genetics

Much progress has been made with our understanding of the genetics of LQTS. At least 13 different, but related, responsible genetic defects have been identified. They all affect ion channels in the cell membranes of heart muscle cells and affect the way that electrical impulses travel through the heart. The 3 most common genetic types are LQT1 (accounting for 40-55% of patients), LQT2 (30-45%), and LQT3 (5-10%). Because these genetic defects affect the ion channels, LQTS is sometimes called a “channelopathy.”

The prevalence is usually said to be approximately 1 per 2000 individuals.

The triggers for lethal and non-lethal cardiac events are different for the genetic subtypes. For carriers of LQT1, the most common trigger is exercise. For carriers of LQT2, exercise is an very uncommon trigger; emotion may be a trigger, but most events occur during sleep or rest without arousal. For carriers of LQT3, few events are triggered by exercise or emotion.

Diagnosis

Most patients come to attention because of a known family history or because of an episode of cardiac syncope or SCD with successful resuscitation.

Most, but not all affected individuals will have prolongation of the QT interval on the EKG. Even without genetic testing, the diagnosis is usually established using a set of diagnostic criteria organized into 3 sections that produce a “Priori-Schwartz score”:

EKG findings
QTc >= 480 msec [3 points]
QTc 460-479 msec [2 points]
QTc 450-459 msec, for men [1 point]
QTc 4th minute of recovery from exercise stress test >=480 msec [1 point]
Torsades-de-Pointes [2 points]
T-wave alternans [1 point]
Notched T wave in 3 leads [1 point]
Low heart rate for age [0.5 point]

Clinical history
Syncope [2 points]
With stress [1 point]
Without stress [1 point]
Congenital deafness [0.5 points]

Family history
Family members with definite LQTS1 [1 point]
Unexplained sudden cardiac death younger than age 30 in family member [0.5 point]

A score of 3.5 points indicates a high probability of LQTS. Some authorities recommend genetic screening for individuals with scores of greater than 3.0 points.

Treatment

Left untreated, symptomatic patients with LQTS have a mortality rate of ~20% in the first year.

Medical therapy includes beta-blockers (eg, propranolol, nadolol). The effectiveness of these medications may depend upon the genetic subtype, but further investigation is ongoing.

One potential surgical option is left cardiac sympathetic denervation (LCSD), a procedure where the ordinarily stimulatory sympathetic nerves are disrupted. This operation can be performed either in an “open” approach or by a thoracoscopic approach. In either case, the first several thoracic ganglia (nerves) are removed. Studies have shown this technique to be effective, particularly among patients with cardiac events despite beta-blocker usage and among patients with problems of various sorts with an implantable cardioverter-defibrillator (ICD).

The ICD is the remaining treatment option. A device is implanted that includes a computer, battery, and leads that are attached to the heart. In the event of a potentially fatal arrhythmia, the device provides a shock to terminate the arrhythmia and restore the normal heart rhythm.

Athletes and LQTS

Consensus guidelines for athletes with LQTS are provided in the Proceedings of the 36th Bethesda Conference. These guidelines recognize that there is not sufficient information (yet) to stratify the risk of SCD for the various genetic subtypes, so a single set of recommendations was offered:

1. Activity should be restricted to low-intensity sports (eg, billiards, golf, curling, riflery) for athletes with LQTS who have had cardiac arrest or an episode of syncope.

2. Asymptomatic athletes with prolongation of the QT interval on the EKG should be restricted to low-intensity sports.

3. Asymptomatic athletes, who are known gene carriers, may participate fully in their sports.

4. Athletes with an ICD should participate only in low-intensity sports and should avoid all situations where bodily injury might occur.

Antonio Puerta, Soccer Player, 1984-2007

January 29, 2013 By Larry Creswell, MD Leave a Comment

Antonio Jose Puerta Perez was a left wing-back soccer player for the Seville Futbol Club. On August 25, 2007, some 35 minutes into a game against Getafe, he collapsed on the field, first grabbing his chest, then kneeling and finally slumping to the ground:

http://www.youtube.com/watch?v=b6f6ohkUS-0

He regained consciousness and actually walked to the dressing room for further care. There, he suffered cardiac arrest, received CPR, and was transported to the hospital. Although he was successfully resuscitated at least twice, he died 3 days later from multi-organ failure. He was 22 years old.

After autopsy, the cause of death was determined to be arrhythmogenic right ventricular dysplasia (ARVD), a known cause of sudden cardiac arrest in young athletes.

ARVD is characterized anatomically by fibrous and/or fatty replacement of normal muscle cells in the right ventricle, the chamber that pumps blood to the lungs. This genetic condition affects approximately 1 per 10,000 Americans but as many as 40 per 10,000 Italians. A handful of genetic defects affecting the cardiac protein, desmin (involved with connections between muscle cells), have been identified.

The diagnosis of ARVD can be difficult, but the presence of a family history of ventricular arrhythmias or sudden cardiac death may be a clue. The EKG may be suggestive and there may be evidence of right ventricle enlargement or fatty deposition on echocardiogram, cardiac CT scan, or cardiac MRI.

Because of its association with sudden cardiac death, the consensus guidelines from the 36th Bethesda Conference on Eligibility Recommendations for Competitive Athletes With Cardiovascular Abnormalities advise that “athletes with probable or definite diagnosis of ARVC should be excluded from most competitive sports….”

Marathon Safety

August 15, 2012 By Larry Creswell, MD 1 Comment

With the unfortunate deaths over this past weekend at two triathlons, I’ve had several conversations with athletes about the general issue of sports-related sudden cardiac death (SCD).

I’ve written previously about the rate of SCA at long-distance running events. We learned from a careful study (of nearly 11 million runners) reported earlier this year [1] that the rate of SCA is approximately 1 per 100,000 marathon participants and approximately 1 per 300,000 half marathon participants. The mean age of victims was 42 years and 86% were men. For the non-surviving victims in whom autopsy information was available, the vast majority had an underlying heart condition such as hypertrophic cardiomyopathy (HCM), other abnormal hypertrophy, heart valve disease, or coronary artery disease.

Interestingly, the occurrences of SCA were not distributed uniformly along the length of the race. In marathons, the SCA events were much more common in the 20 mile-to-finish segment. Similarly, in half marathons, the SCA events were much more common in the 10 mile-to-fiinish segment. One reasonable hypothesis is that the SCA events in the final miles of the races may be linked to an increase in adrenaline levels as runners lift the pace or surge toward the finish line.

Today, I thought I’d share some recommendations from the International Marathon Medical Director’s Association (IMMDA) that were approved in March, 2010 and address the issue of how athlete’s can best prepare and execute a long-distance running race with an eye toward preventing SCA. You can review the original report to review the rationale, but I’ll summarize the important recommendations here:

1. Participants should be well-trained and have a race plan that matches their level of training and fitness.

2. Have a yearly physical examination being sure to discuss your exercise plans, goals, and intensity at that visit.

3. Consume a baby aspirin (81 mg) on the morning of the race if there is no contraindication to do so. I’d recommend discussing this with your doctor beforehand.

4. Consume less than 200 mg of caffeine before/during a 10K or longer race.

5. Only drink sports drink (or equivalent) in races of 10K+.

6. Drink for thirst.

7. Do not consume NSAIDS (eg, Motrin, ibuprofen) during a race of 10K+.

8. Consume salt (if no medical contraindication) during a 10K+ race.

9. During the last mile, maintain your pace or slow down; do not sprint the last part of the race unless you have practices this in your training.

These are very thoughtful recommendations. The chances of any single athlete suffering race-related sudden cardiac death is small, but athletes should do the reasonable things to help prevent this type of tragedy.

[1] Kim JH, et al. Cardiac arrest during long-distance running races. NEJM 2012;366:130-140.