Short QT syndrome

An increased or abnormal awareness of the heartbeat, palpitations are a common symptom in patients presenting to family physicians. Palpitations can be symptomatic of life-threatening cardiac arrhythmias. (1) However, most palpitations are benign. In one retrospective study (2) in a family practice setting, there was no difference in the rates of morbidity or mortality among patients with palpitations compared with matched control subjects.

Although there are many possible cardiac etiologies, palpitations can be associated with noncardiac causes such as fever, anemia, or drug use, and can occur in anxious but otherwise normal persons. The differential diagnoses of palpitations are summarized in Table 1.

Consensus or evidence-based guidelines for diagnosing and managing palpitations have not been developed. However, recent studies of palpitation etiology provide improved evidence that can guide a family physician through diagnosis. In a prospective cohort study (1) of 190 patients at a university medical center who complained of palpitations and were followed for one year, an etiology was determined in 84 percent of the patients.

Of these patients, 43 percent had palpitations caused by cardiac causes (40 percent had an arrhythmia, 3 percent had other cardiac causes), 31 percent had palpitations caused by anxiety or panic disorder, 6 percent had palpitations caused by street drugs or prescription and over-the-counter medications, and 4 percent had palpitations caused by other noncardiac causes. No specific cause of the palpitations could be identified in 16 percent of the patients. Psychiatric and emotional illnesses such as anxiety, panic, and somatization disorders may be underlying problems in many patients. (1)

Although arrhythmias frequently cause palpitations, most patients with arrhythmias do not actually notice their arrhythmia and are unlikely to report having palpitations. (3)

This article describes the more common presentations of palpitations and a rational approach to patient evaluation, and provides evidence for making decisions about ambulatory monitoring.

Etiology of Palpitations

CARDIAC ARRHYTHMIAS

Palpitations can result from many arrhythmias, including any bradycardia and tachycardia, premature ventricular and atrial contractions, sick sinus syndrome, advanced arteriovenous block, or ventricular tachycardia. Episodes of ventricular tachycardia and supraventricular tachycardia may be perceived as palpitations but also can be asymptomatic or lead to syncope. Palpitations associated with dizziness, near-syncope, or syncope suggest tachyarrhythmia and are potentially more serious.

Some patients notice "pounding" or "jumping" palpitations when they are quietly sitting or lying down. This symptom may result from premature contractions, especially premature ventricular contractions. Orthostatic intolerance or inadequate cerebral perfusion on upright posture may result in palpitations, tachycardia, altered mentation, headache, nausea, pre-syncope, and, occasionally, syncope. Orthostatic intolerance is most common in women of childbearing age. (4)

ANXIETY OR PANIC DISORDER

The prevalence of panic disorder in patients with palpitations is 15 to 31 percent. (1,5,6) Panic disorder is diagnosed on the basis of information in the patient's history and is characterized by recurrent unexpected panic attacks. Panic disorder is more likely to be diagnosed in women of childbearing age because these patients somatize more frequently, present to emergency departments more often, and have increased hypochondriacal concerns about their health. (7) Palpitations are most persistent in persons who have many minor daily irritants and are highly sensitive to bodily sensations. (8)

A screening questionnaire (Figure 1) (9) to help identify patients whose palpitations are more likely to result from panic disorder was validated among patients referred for Holter monitoring. A score of more than 21 points on the questionnaire is 81 percent sensitive and 80 percent specific for panic disorder. To explain it another way, if, overall, 25 percent of patients have panic disorder as the cause of their palpitations, then 57 percent with more than 21 points have panic disorder compared with only 7 percent of those with 21 or fewer points. (9)

A simpler screening tool for panic disorder, consisting of a single question, also has been developed. The question is, "Have you experienced brief periods, for seconds or minutes, of an overwhelming panic or terror that was accompanied by racing heartbeats, shortness of breath, or dizziness?" (10) The physician must remember that panic disorder and significant arrhythmias are not mutually exclusive, and that cardiac evaluation still may be necessary in patients with suspected panic disorder. In addition, some patients or physicians may find it difficult to determine whether the feeling of anxiety or panic started before or after the palpitations. Therefore, true arrhythmic causes must be ruled out before the diagnosis of anxiety or panic disorder can be accepted as the cause of the palpitations. (1,11,12)

Some physicians may prematurely blame palpitations on anxiety. In one study (13) of patients with supraventricular tachycardia, two thirds of the patients were diagnosed with panic, stress, or anxiety disorder, and one half of the patients had an unrecognized arrhythmia on the initial evaluation; this was particularly true among young women.

Catecholamines increase at times of intense emotional experience, with intense exercise, and in conditions such as pheochromocytoma. Ventricular tachycardias or supraventricular tachycardias can be triggered by this catecholamine increase. An increase of vagal tone after exercise occasionally can lead to episodes of atrial fibrillation. (14) Thus, even in cases where panic disorder is suggested, electrocardiography (ECG) or ambulatory ECG monitoring is important.

NONARRHYTHMIC CARDIAC CAUSES

Conditions in this category include valvular diseases such as aortic insufficiency or stenosis, atrial or ventricular septal defect, congestive heart failure, cardiomyopathy, and congenital heart disease. These conditions can predispose the patient to arrhythmia and to palpitations. Pericarditis, a rare cause of palpitations, can cause chest pain that may change with position.

EXTRACARDIAC CAUSES

The physician should examine the patient for extracardiac causes. The patient may have obvious associated illness with fever, dehydration, hypoglycemia, anemia, or evidence of thyrotoxicosis. Use of drugs such as cocaine, and alcohol, caffeine, and tobacco can precipitate palpitations. The use of ephedra and ephedrine also has been associated with palpitations. (15) Many prescription medications, including digitalis, phenothiazine, theophylline, and beta agonists, can cause palpitations.

Initial Clinical Evaluation

HISTORY AND PHYSICAL EXAMINATION

The cause of palpitations often can be determined through a careful history and physical examination. Patients may describe palpitations in a variety of ways, such as a fluttering, pounding, or uncomfortable sensation in the chest or neck, or simply an increased awareness of the heartbeat. Because the patient's description is often vague, knowing the circumstances, precipitating factors, and associated symptoms may be helpful for the physician in diagnosis. For example, a patient who describes single "skipped" beats is likely to be having benign premature ventricular contractions. The physician should consider the differential diagnoses of palpitations (Table 1) while questioning the patient. Certain clinical findings and possible associated conditions are listed in Table 2.

Because physicians usually do not get the chance to examine the patient during an episode of palpitations, the physical examination primarily serves to determine if there are cardiac or other abnormalities present that might predispose the patient to palpitations. Careful examination of the heart may reveal murmurs, extra sounds, or cardiac enlargement. Mitral valve prolapse, which is commonly associated with palpitations, is suggested by a midsystolic click. (16) The physician should look for evidence of hyperthyroidism (e.g., nervousness, heat intolerance), drug use, or other serious illnesses. Finally, in the occasional patient who has palpitations with exercise, examination of the patient after he or she exercises may reveal an arrhythmia or murmur that is exacerbated by the resulting increased heart rate and cardiac output.

ECG EVALUATION

A 12-lead ECG evaluation is appropriate in all patients who complain of palpitations. In the event that the patient is experiencing palpitations at the time of the ECG, the physician may be able to confirm the diagnosis of arrhythmia. Many ECG findings warrant further cardiac investigation. These findings include evidence of previous myocardial infarction, left or right ventricular hypertrophy, atrial enlargement, atrial ventricular block, short PR interval and delta waves (Wolff-Parkinson-White syndrome), or prolonged QT interval. Occasionally, the finding of an isolated premature ventricular contraction or premature atrial contraction warrants further monitoring or exercise testing. Some common arrhythmias associated with palpitations are shown in Figures 2 through 5.

[FIGURES 2-5 OMITTED]

Further Diagnostic Testing

In patients at low risk for coronary heart disease who have no palpitation-associated symptoms such as dizziness, and who have negative physical examination and ECG findings, palpitations may need no further evaluation unless the episodes persist or the patient remains anxious for an explanation. Blood tests may be appropriate in the following conditions: complete blood cell count for suspected anemia or infection, electrolytes for arrhythmia from suspected electrolyte imbalance, and thyroid-stimulating hormone for suspected hyperthyroidism or hypothyroidism.

ECG exercise testing is appropriate in patients who have palpitations with physical exertion and patients with suspected coronary artery disease or myocardial ischemia. Findings from the physical examination or ECG may suggest the need for echocardiography to evaluate structural abnormalities and ventricular function.

High-risk patients, who require ECG monitoring, include those with organic heart disease or any heart abnormality that could predispose the patient to arrhythmias. Patients with a family history of arrhythmia, syncope, or sudden death also may be at higher risk. The results of one study (17) of 24-hour ECG monitoring showed that ventricular tachycardia was associated with previous myocardial infarction, idiopathic dilated cardiomyopathy, significant valvular lesions, and hypertrophic cardiomyopathies.

If the etiology of palpitations is not apparent after the history, physical examination, and ECG are completed, the physician should consider ambulatory cardiac monitoring. Figure 6 is an algorithm that can be used in the evaluation of patients with palpitations.

[FIGURE 6 OMITTED]

CONTINUOUS ECG MONITORS

The Holter monitor is a simple ECG monitoring device that is worn continuously to record data for 24 or 48 hours. The patient must keep a diary of any symptoms that occur during the monitoring. (17) Holter monitors typically are the most expensive of the monitoring devices, and are maintained and operated by hospitals or larger outpatient clinics.

TRANSTELEPHONIC EVENT MONITORS

Transtelephonic event monitors transmit recordings by telephone to a central station. As with Holter monitors, patients wear continuous-loop event monitors, but unlike Holter monitors, these save data only for the previous and subsequent few minutes when the patient manually activates the monitor. These monitors are smaller than a Holter monitor (i.e., the size of a beeper) and may miss arrhythmias that are asymptomatic, or that occur during sleep or with syncope. Another type of transtelephonic monitor is not worn continuously but is carried by the patient and held to the chest when palpitations are perceived. This monitor records ECG data for about two minutes and is likely to miss the onset of arrhythmia.

Choosing an Ambulatory Monitoring Device

The results of a review (18) of studies comparing Holter monitors and transtelephonic event monitors in the diagnosis of palpitations found that the diagnostic yield was 66 to 83 percent when event monitors were used for monitoring, and 33 to 35 percent when Holter monitors were used. Furthermore, event monitors have been found to be significantly more cost effective than Holter monitors. (19,20) The results of retrospective and prospective trials (19,20) showed that 83 to 87 percent of patients had diagnostic transmissions within the first two weeks of using a transtelephonic event monitor.

Evidence supports the use of an initial two-week course of continuous closed-loop event recording to monitor for palpitations. Holter monitoring for 24 hours is an alternative to event monitoring in patients who reliably experience palpitations every day, or who are not willing to wear an event monitor for two weeks, and if event monitoring is not available locally. When palpitations are sustained or poorly tolerated, a referral to a cardiologist for an electrophysiologic evaluation may be warranted. (21)

Management

In patients with arrhythmias, the most common finding on ambulatory monitoring is benign atrial or ventricular ectopic beats associated with normal sinus rhythm. (20-22) Normal sinus rhythm alone is found in about one third of patients. Many patients with palpitations have ventricular premature contractions or brief episodes of ventricular tachycardia; if the evaluation of the heart is otherwise normal, these findings are not associated with increased mortality. (23) Appropriate patient education is indicated in these patients. The treatment of sustained arrhythmias involves pharmacologic or invasive electrophysiologic management and is beyond the scope of this article.

If the patient is diagnosed with a non-cardiac, psychiatric, or nonarrhythmia cardiac etiology, the underlying condition is managed according to the diagnosis. In some patients, a thorough history, physical examination, diagnostic testing, and cardiac monitoring all fail to reveal any abnormality or etiology for palpitations. These patients should be advised to abstain from caffeine and alcohol, as well as foods or stressful situations that appear to trigger palpitations. Fortunately, the majority of patients with palpitations have benign diagnoses and can be treated with reassurance.

REFERENCES

(1.) Weber BE, Kapoor WN. Evaluation and outcomes of patients with palpitations. Am J Med 1996;100:138-48.

(2.) Knudson MP. The natural history of palpitations in a family practice. J Fam Pract 1987;24:357-60.

(3.) Barsky AJ. Palpitations, arrhythmias, and awareness of cardiac activity. Ann Intern Med 2001;134(9 pt 2):832-7.

(4.) Ali YS, Daamen N, Jacob G, Jordan J, Shannon JR, Biaggioni I, et al. Orthostatic intolerance: a disorder of young women. Obstet Gynecol Surv 2000;55:251-9.

(5.) Chignon JM, Lepine JP, Ades J. Panic disorder in cardiac outpatients. Am J Psychiatry 1993;150:780-5.

(6.) Barsky AJ, Cleary PD, Coeytaux RR, Ruskin JN. Psychiatric disorders in medical outpatients complaining of palpitations. J Gen Intern Med 1994;9:306-13.

(7.) Jeejeebhoy FM, Dorian P, Newman DM. Panic disorder and the heart: a cardiology perspective. J Psychosom Res 2000;48:393-403.

(8.) Barsky AJ, Ahern DK, Bailey ED, Delamater BA. Predictors of persistent palpitations and continued medical utilization. J Fam Pract 1996;42:465-72.

(9.) Barsky AJ, Ahern DK, Delamater BA, Clancy SA, Bailey ED. Differential diagnosis of palpitations. Preliminary development of a screening instrument. Arch Fam Med 1997;6:241-5.

(10.) Ballenger JC. Treatment of panic disorder in the general medical setting. J Psychosom Res 1998;44:5-15.

(11.) Barsky AJ, Cleary PD, Coeytaux RR, Ruskin JN. The clinical course of palpitations in medical outpatients. Arch Intern Med 1995;155:1782-8.

(12.) Zimetbaum P, Josephson ME. Evaluation of patients with palpitations. N Engl J Med 1998;338:1369-73.

(13.) Lessmeier TJ, Gamperling D, Johnson-Liddon V, Fromm BS, Steinman RT, Meissner MD, et al. Unrecognized paroxysmal supraventricular tachycardia. Potential for misdiagnosis as panic disorder. Arch Intern Med 1997;157:537-43.

(14.) Coumel P. Clinical approach to paroxysmal atrial fibrillation. Clin Cardiol 1990;13:209-12.

(15.) Shekelle PG, Hardy ML, Morton SC, Maglione M, Mojica WA, Suttorp MJ, et al. Efficacy and safety of ephedra and ephedrine for weight loss and athletic performance: a meta-analysis. JAMA 2003;289:1537-45.

(16.) Duren DR, Becker AE, Dunning AJ. Long-term follow-up of idiopathic mitral valve prolapse in 300 patients: a prospective study. J Am Coll Cardiol 1988;11:42-7.

(17.) Wolfe RR, Driscoll DJ, Gersony WM, Hayes CJ, Keane JF, Kidd L, et al. Arrhythmias in patients with valvar aortic stenosis, valvar pulmonary stenosis, and ventricular septal defect. Results of 24-hour ECG monitoring. Circulation 1993;87(2 suppl):189-101.

(18.) Zimetbaum PJ, Josephson ME. The evolving role of ambulatory monitoring in general clinical practice. Ann Intern Med 1999;130:848-56.

(19.) Fogel RI, Evans JJ, Prystowsky EN. Utility and cost of event recorders in the diagnosis of palpitations, presyncope, and syncope. Am J Cardiol 1997;79:207-8.

(20.) Kinlay S, Leitch JW, Neil A, Chapman BL, Hardy DB, Fletcher PJ, et al. Cardiac event recorders yield more diagnoses and are more cost-effective than 48-hour Holter monitoring in patients with palpitations. A controlled clinical trial. Ann Intern Med 1996;124(1 pt 1):16-20.

(21.) Zimetbaum PJ, Kim KY, Josephson ME, Goldberger AL, Cohel DJ. Diagnostic yield and optimal duration of continuous-loop event monitoring for the diagnosis of palpitations. A cost-effectiveness analysis. Ann Intern Med 1998;128:890-5.

(22.) Zimetbaum PJ, Kim KY, Ho KK, Zebede J, Josephson ME, Goldberger AL. Utility of patient-activated cardiac event recorders in general clinical practice. Am J Cardiol 1997;79:371-2.

(23.) Kennedy HL, Whitlock JA, Sprague MK, Kennedy LJ, Buckingham TA, Goldberg RJ. Long-term follow-up of asymptomatic healthy subjects with frequent and complex ventricular ectopy. N Engl J Med 1985;312:193-7.

* Patient information: A handout on heart palpitations, written by the author of this article, is provided on page 755.

ALLAN V. ABBOTT, M.D., is professor of clinical family medicine at the Keck School of Medicine of the University of Southern California, Los Angeles, where he is associate dean for curriculum and continuing medical education. Dr. Abbott received his medical degree from Indiana University School of Medicine and completed a residency in family medicine at UCLA San Bernardino Medical Center, Calif.

Address correspondence to Allan V. Abbott, M.D., 1975 Zonal Ave., KAM 317, Los Angeles, CA 90033 (e-mail: allana@usc.edu). Reprints are not available from the author.

The author indicates that he does not have any conflicts of interest. Sources of funding: none reported.

Figures 2 through 5 used with permission from Allan V. Abbott, M.D.

This article is one in a series on problem-oriented diagnosis coordinated by the Department of Family Medicine at the University of Southern California, Los Angeles, Calif.

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