Evaluation and management of premature ventricular complexes

Nondihydropyridine calcium channel blockers

Nondihydropyridine calcium channel blockers are particularly effective for PVC suppression in patients without structural heart disease by the mechanisms previously described involving intracellular calcium channels. In particular, they are highly effective and are considered the drugs of choice in treating fascicular PVCs.

Verapamil is a potent drug in this class, but it also commonly causes constipation as a side effect. Diltiazem is less constipating but can cause fatigue, drowsiness, and headaches. Both drugs reduce the resting heart rate and slow atrioventricular nodal conduction. Patients predisposed to bradycardia or atrioventricular block can develop dizziness or overt syncope. Calcium channel blockers are also used cautiously in patients with congestive heart failure, given their potential negative inotropic effects.

Overall, calcium channel blockers are a very reasonable choice for young patients without structural heart disease who need PVC suppression.

Other antiarrhythmic drugs

Sotalol merits special consideration because it has both beta-blocker and class III antiarrhythmic properties, blocking potassium channels and prolonging cardiac repolarization. It can be very effective in PVC suppression but also creates some degree of QT prolongation. The QT-prolonging effect is accentuated in patients with baseline QT prolongation or abnormal renal function. Rarely, this can lead to torsades de pointes. As a safety precaution, some patients are admitted to the hospital when they start sotalol therapy so that they can be monitored with continuous telemetry and ECG to detect excessive QT prolongation.

Amiodarone is a versatile drug with mixed pharmacologic properties that include a predominantly potassium channel-blocking class III drug effect. However, this effect is balanced by its other pharmacologic properties that make QT prolongation less of a clinical concern. Excessive QT prolongation may still occur when used concomitantly with other QT-prolonging drugs.

Amiodarone is very effective in suppressing PVCs and ventricular arrhythmias but has considerable short-term and long-term side effects. Cumulative toxicity risks include damage to the thyroid gland, liver, skin, eyes, and lungs. Routine thyroid function testing, pulmonary function testing, and eye examinations are often considered for patients on long-term amiodarone therapy. Short-term use of this drug does not typically require such surveillance.

Catheter ablation

As mentioned in the previous sections, catheter ablation is a safe and effective treatment for PVCs. It is curative in most cases, and significantly reduces the PVC burden in others.

Procedure. Patients are brought to the electrophysiology laboratory in a fasted state and are partially sedated with an intravenous drug such as midazolam or fentanyl, or both. Steerable catheters are placed into appropriate cardiac chambers from femoral access sites, which are infiltrated with local anesthesia. Sometimes sedative or analgesic drugs must be limited if they are known to suppress PVCs.

Most operators prefer a technique called activation mapping, in which the catheter is maneuvered to home in on the precise PVC origin within the heart, which is subsequently ablated. This technique has very high success rates, but having enough spontaneous PVCs to map during the procedure is essential for the technique to succeed. Conversely, not having sufficient PVCs on the day of the procedure is a common reason that ablation fails or cannot be performed at all.

Pace-mapping is an alternate technique that does not require a continuous stream of PVCs. This involves pacing from different candidate locations inside the heart in an effort to precisely match the ECG appearance of the clinical PVC and to ablate at this site. Although activation mapping generally yields higher success rates and is preferred by most operators, pace-mapping can be successful when a perfect 12–12 match is elicited. In many cases, the two techniques are used together during the same procedure, particularly if the patient’s PVCs spontaneously wax and wane, as they often do.

Risks. Like any medical procedure, catheter ablation carries some inherent risks, including rare but potentially serious events. Unstable arrhythmias may require pace-termination from the catheter or, rarely, shock-termination externally. Even more rare is cardiac arrest requiring cardiopulmonary resuscitation. Uncommon but life-threatening complications also include pericardial effusion or cardiac tamponade requiring percutaneous drainage or, rarely, emergency surgical correction. Although such events are life-threatening, death is extremely rare.

Complications causing permanent disability are also very uncommon but include the risk of collateral injury to the conduction system requiring permanent pacemaker placement, injury to the coronary vessels requiring urgent treatment, or diaphragmatic injury affecting breathing. Left-sided cardiac ablation also carries a small risk of stroke, which is mitigated by giving intravenous heparin during the procedure.

More common but generally non-life-threatening complications include femoral vascular events such as hematomas, pseudoaneurysms, or fistulas that sometimes require subsequent treatment. These complications are generally treatable but can significantly prolong the recovery period.

Catheter ablation procedures are typically 2 to 6 hours in duration, depending on the chambers involved, PVC frequency, and other considerations. Postprocedure bed rest is required for a number of hours. A Foley catheter is sometimes used for patient comfort when a prolonged procedure is anticipated. This carries a small risk of urinary tract infection. Epicardial catheter ablation that requires access to the surface of the heart (ie, the pericardial space) is uncommon but carries some unique risks, including rare injury to coronary vessels or adjacent organs such as the liver or stomach.

Overall, both endocardial and epicardial catheter ablation can be performed safely and effectively in the overwhelming majority of patients, but understanding and explaining the potential risks remains a crucial part of the informed consent process.

TAKE-HOME POINTS

• PVCs are a common cause of palpitations but are also noted as incidental findings by ECG, Holter monitoring, and inpatient telemetry.
• The diagnostic evaluation includes an assessment for underlying structural heart disease and quantification of the total PVC burden.
• Patients without structural heart disease and with low-to-modest PVC burdens may not require specific treatment. PVCs at greater burdens, typically 15% to 20%, or with specific high-risk features carry a risk of tachycardia-related cardiomyopathy and may require treatment even if they are asymptomatic. These high-risk features include initial QRS slurring and PVCs occurring at shorter coupling intervals.
• Treatment involves medical therapy with a beta-blocker, a calcium channel blocker, or another antiarrhythmic drug, and catheter ablation in selected cases.
• Catheter ablation can be curative but is typically reserved for drug-intolerant or medically refractory patients with a high PVC burden.