The present study aims to identify and compare the efficacy and safety of two different session frequency protocols (once vs twice per week) of low intensity extracorporeal shockwave treatment (LI-ESWT) using Aries ED device, in men with mild-moderate and severe vasculogenic ED, who have previously responded to oral PDE5-Is

This is a randomized, 2 parallel arms, clinical trial. All patients will be PDE5I users/responders. After 1 month wash-out period, ED patients will be screened, in order to randomized 42 men with vasculogenic ED who had International Index of Erectile Function ED (IIEF-ED) domain scores between 6-25 and abnormal penile triplex-based hemodynamic parameters (peak flow velocity <35cm/sec). Then the 42 pts will be randomized to receive either one or two shockwave treatment sessions per week, without treatment interval. Every week all subjects may have at least one attempt for intercourse. All patients will complete 6 weeks of treatment.

Study visits and duration

Visit 1 (day 0): the basic work-up will take place, including medical and sexual history, as well as necessary lab tests, if needed. One month wash-out period will follow. During this period, all subjects will be asked to avoid any drug related to ED (PDE5i) and have at least 2-4 attempts for intercourse. Furthermore, patients will undergo triplex ultrasonography, unless they have already done so in the last 6 months. all patients will complete the IIEF-ED domain and will be randomized (1:1) to one of the two parallel study groups, using an online program. Groups A will receive treatment once per week for 6 weeks (6 sessions totally), and Groups B will receive treatment two times per week for 6 weeks (12 sessions totally). PDE5i use is prohibited throughout the study.

Treatment Visits: Patients will receive LI-ESWT , according to the study protocol.Interval between 2 treatments will be 7+2days for Group A and 3+1 day for Group B.At visit 6 and 12 a penile ultrasonography will be conducted in order to check for potential adverse events related to the treatment.

Follow-up visits 1 - 3 (4, 12 and 24 weeks post treatment): Patients will complete the IIEF-ED questionnaire and return the completed SEP diaries for the last 4 weeks prior to every visit. Visit data will also be recorded (protocol compliance, adverse events). At Week 12, triplex will be performed by the standard protocol. For Week 4 there is a + 3 days visit window, whereas for Weeks 12 and 24 there is a + 2 weeks visit window.

Inclusion Criteria:

1. Consent to participate
2. Age >18
3. Presence of vasculogenic erectile dysfunction for at least 6 months
4. Positive response to PDE5i
5. IIEF-ED score > 6 and IIEF score < 26 after wash out of PDE5i
6. Abnormal penile triplex-based hemodynamic parameters (peak flow velocity <35cm/sec)
7. Stable heterosexual relationship for more than 3 months
8. Sexually active and agree to suspend all ED therapy for the duration of study

Exclusion Criteria:

1. Any cause of ED other than vascular related
2. Previous radiation therapy to pelvis
3. History of radical prostatectomy
4. Clinically significant chronic haematological disease
5. Cardiovascular conditions that prevent sexual activity
6. Peyronie's Disease or penile curvature
7. History of heart attack, stroke or any life- threatening arrhythmia within the prior 6 month
8. Anti-androgens oral or injectables androgens
9. Untreated Hypogonadism as demonstrated by abnormal testosterone levels
10. Malignancy within the past 5 years
11. Any unstable medical, psychiatric condition or spinal cord injury
12. Anatomical or neurological abnormalities in the treatment area
13. Use of any treatment for ED within 7 days of screening ( oral medications, vacuum devices, constrictive devices, injections or urethral suppositories)
14. Known allergy to ultrasound gel